RESEARCH ARTICLE

The Minimal Phenomenal Experience

questionnaire (MPE-92M): Towards a

phenomenological profile of “pure

awareness” experiences in meditators

Alex GammaID

1☯*, Thomas Metzinger2☯*

1 Research Department, University Hospital of Psychiatry, Zu  rich, Switzerland, 2 Arbeitsbereich

Theoretische Philosophie, Philosophisches Seminar, Johannes Gutenberg University, Mainz, Germany

☯ These authors contributed equally to this work.

* alex.gamma@uzh.ch (AG); metzinger@uni-mainz.de (TM)

Abstract

Objective

To develop a fine-grained phenomenological analysis of “pure awareness” experiences in

meditators.

Methods

An online survey in five language versions (German, English, French, Spanish, Italian) collected

data from January to March 2020. A total of 92 questionnaire items on a visual analogue

scale were submitted to exploratory and confirmatory factor analysis.

Results

Out of 3627 submitted responses, 1403 were usable. Participants had a median age of 52

years (range: 17–88) and were evenly split between men and women (48.5% vs 50.0%).

The majority of meditators practiced regularly (77.3%), were free of diagnosed mental disorders

(92.4%) and did not regularly use any psychoactive substances (84.0%). Vipassana

(43.9%) followed by Zen (34.9%) were the most frequently practiced meditation techniques.

German (63.4%) and English (31.4%) were by far the most frequent questionnaire languages.

A solution with 12 factors explaining 44% of the total variance was deemed optimal

under joint conceptual and statistical considerations. The factors were named “Time, Effort

and Desire,” “Peace, Bliss and Silence,” “Self-Knowledge, Autonomous Cognizance and

Insight,” “Wakeful Presence,” “Pure Awareness in Dream and Sleep,” “Luminosity,”

“Thoughts and Feelings,” “Emptiness and Non-egoic Self-awareness,” “Sensory Perception

in Body and Space,” “Touching World and Self,” “Mental Agency,” and “Witness Consciousness.”

This factor structure fit the data moderately well.

Conclusions

We have previously posited a phenomenological prototype for the experience of “pure

awareness” as it occurs in the context of meditation practice. Here we offer a tentative 12-

PLOS ONE

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OPEN ACCESS

Citation: Gamma A, Metzinger T (2021) The

Minimal Phenomenal Experience questionnaire

(MPE-92M): Towards a phenomenological profile

of “pure awareness” experiences in meditators.

PLoS ONE 16(7): e0253694. https://doi.org/

10.1371/journal.pone.0253694

Editor: Jane Elizabeth Aspell, Anglia Ruskin

University, UNITED KINGDOM

Received: November 4, 2020

Accepted: June 11, 2021

Published: July 14, 2021

Peer Review History: PLOS recognizes the

benefits of transparency in the peer review

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https://doi.org/10.1371/journal.pone.0253694

Copyright:   2021 Gamma, Metzinger. This is an

open access article distributed under the terms of

the Creative Commons Attribution License, which

permits unrestricted use, distribution, and

reproduction in any medium, provided the original

author and source are credited.

Data Availability Statement: The data,

documentation and all language versions of the

MPE-92M questionnaire are publicly available as a

factor model to describe its phenomenal character in a fine-grained way. The current findings

are in line with an earlier study extracting semantic constraints for a working definition

of minimal phenomenal experience.

Introduction

The concept of “pure consciousness” or “pure awareness” has a long tradition in the literature

on contemplative practices. It refers to the meditator’s subjective experience of consciousness

as such, wherein he or she is non-conceptually aware of being aware. Pure awareness is often

described as a contentless form of experience, and it has played a great role in Eastern philosophical

traditions. Over the centuries, contemplative practice has mostly taken place against

the background of religious belief systems like Buddhism or Hinduism, with meditators trying

to achieve a soteriological goal like “liberation” or “enlightenment.” Accordingly, the phenomenological

taxonomies of such states have been shaped by metaphysical belief systems and an

ancient, traditional cultural context. However, during the last 50 years, a historically new situation

has emerged: Millions of practitioners in Western societies meditate regularly, on a daily

basis, but many of them do so in a secular context and describe themselves a “spiritual but not

religious” (SBNR).

Scientific research in the past century has occasionally taken an interest in states of “pure

awareness,” but mostly from a descriptive angle and using qualitative methods ([1, 2]; for a

review see [3]). Quantitative, including psychometric, approaches have been lacking, particularly

with regard to the phenomenology of such experiences [3–6].

What has emerged from the little research conducted so far has been in line with the traditional

literature, showing states of pure awareness to be characterized by an “absence of

space and time, or body sense” and by the experience of “peacefulness” and “unboundedness”

[2]. Some authors have studied particular aspects of pure consciousness experiences,

such as non-dual awareness. For example, Hanley et al. [7] found two dimensions of the

experience of non-dual awareness: self-transcendence (a dissolving of the boundaries of

the self and a feeling “oneness” with everything around) and bliss (feelings of peacefulness,

love and blissful warmth). Most topical research, however, is more tangential to the phenomenon

of pure awareness, which appears as part of a construct (e.g. in the “mystical”

factor of the Mystical Experience Questionnaire MEQ30 [8]), but is not itself the focus of

investigation.

Here, we study pure awareness specifically, using a psychometric approach and a philosophical

background theory. We present data from the Minimal Phenomenal Experience

(MPE) project, an interdisciplinary initiative aiming at a minimal model explanation of conscious

experience, taking the phenomenal character of “pure consciousness” or “pure awareness”

in meditation as its empirical entry point (for an introduction, cf. [9], sections 1 and 2).

The MPE project has two metatheoretical goals that correspond to two fundamental motivating

questions: What, if anything, can count as the simplest form of conscious experience?

And is it possible to arrive at a minimal model explanation for conscious experience in neurotypical

human beings?

Typical examples of questions related to the first goal are: Phenomenologically, can a conscious

system be exclusively aware of awareness itself? Please note how the concept of “awareness”

we use is a phenomenological one, and not a metaphysical one (which might involve

treating awareness as a Kantian “thing in itself,” or even some mysteriously self-conscious

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ZIP-file on the Open Science Framework website.

URL: https://osf.io/gb76x/download.

Funding: This work was funded by a 5-year

Fellowship awarded to TM by the Gutenberg

Research College, Johannes Gutenberg-Universita t

Mainz (https://www.grc.uni-mainz.de/). The funder

had no role in study design, data collection and

analysis, decision to publish, or preparation of the

manuscript.

Competing interests: The authors have declared

that no competing interests exist.

homunculus looking at awareness itself, etc.). This evidence-based phenomenological

approach implies the possibility of non-egoic self-awareness, i.e., an experience of awareness

itself that is not even subjective in the sense of being tied to a consciously experienced first-person

perspective or a personal-level self-model anymore (see the discussion of Factor 3 and 8

below). If so, would there be a specific form of phenomenal character, a specific experiential

quality that is instantiated during such episodes of pure awareness? Is there something like the

simplest form of conscious experience, and if so, what exactly are the conceptual criteria for

phenomenological “minimality”? Neuroscientifically, what are the minimally sufficient correlates

for MPE to occur in neurotypical humans?

The second goal is to explore a new explanatory strategy. For empirical consciousness

research, the idea is to develop a heuristic strategy of minimalist idealization, by describing

the target phenomenon in an uncluttered way, abstracting away from everything that is not

an essential feature of the core explanandum [9]. For the target of phenomenal consciousness,

does consciousness per se have a distinct experiential character? Does it ever occur in

isolation, and can it be described in a conceptually precise manner? Part of the idea is to look

for the decisive explanatory and computational factors by first attempting to construct

exactly solvable minimal models ([10], p. 37). Such minimal models do not aim at maximal

fidelity or completeness; they are not yet mappings to fine-grained functional mechanisms,

and in this sense, they are idealizations. However, they can be crucial in generating a “minimal

model explanation” [10, 11]. Minimalist idealization proceeds by means of: researchers

constructing and further investigating a parsimonious model of conscious experience that

goes beyond mere correlation but includes only the core causal factors giving rise to the target

phenomenon; including only those causal factors that make a difference to the actual occurrence

and the essential phenomenal character itself; developing an idealized model of universal

and repeatable features serving to gradually isolate the fundamental, explanatorily

relevant, and structurally stable properties that underlie all different forms of conscious

experience. Here, constructing such a minimal model would amount to eliminating superfluous

details by extracting only the explanatorily relevant causal structure underlying the

experience of awareness per se.

The project’s basic working hypothesis is that there exists a form of “minimal phenomenal

experience” (MPE hereafter; [9, 12]) that lacks time representation, spatial self-location,

agency, autobiographical self-awareness, and a phenomenally experienced first-person perspective.

This can be understood as an unstructured form of global content that is also devoid

of perceptual, motor, affective, conceptual and propositional content.

Therefore, the project’s overarching epistemic goal is to find out whether anything like

“pure consciousness” really exists: Is there a state in which only consciousness per se is phenomenally

experienced? However, as an empirical investigation, the current study does not

prejudge the question of the absence of specific contents. Rather, it allows for the possibility

that the non-conceptual experience of consciousness as such can co-occur with conscious

contents. This corresponds to a theoretical treatment of MPE as a phenomenological prototype

without sharp definitional boundaries. We also limit ourselves to one plausibly homogeneous

subclass of MPE states, a paradigmatic form of “pure consciousness” experience as it

appears in the context of systematic and formal contemplative practice. From the relevant

body of Eastern and Western literature and based on a series of pilot studies involving committed

practitioners, we extracted 92 characteristics of the phenomenology of pure consciousness

experiences, which were then formed into questionnaire items. The aim of our

study is to use the questionnaire data to find clusters within these items that could serve

as coherent and meaningful phenomenological dimensions of the experience of pure

awareness.

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Materials and methods

Data collection

Data were collected from Jan 04, 2020 to April 01, 2020 using an online survey hosted on SurveyGizmo

(recently renamed to Alchemer). In phase I, a personal invitation translated into the

five survey languages and containing a link to the survey was emailed by TM to a number of

regular and committed practitioners of meditation. Recipients were asked to further distribute

the survey link. In phase II, the call for participation was extended, via social media, to relevant

organizations and groups all over the world. According to the guidelines of the local ethics

committee of the Department of Psychology of Johannes Gutenberg-Universita t no formal

ethics approval was necessary, because the current study satisfies all criteria for safety and

clearance.

Participants

A total of 3627 survey responses were submitted. Theoretically, the requirement for a respondent

to be included in the factor analysis was to have had at least one experience of "pure

awareness" (N = 2257) and to have submitted complete answers to the 92 items (N = 1171).

In practice, both restrictions were slightly relaxed: 17 participants who failed to answer the

screening question about pure awareness but nevertheless had complete questionnaire data

were kept in the dataset. Respondents with answers to at least 86 items were also retained, as

this increased the analysis sample by over 200 cases compared to those with all 92 items completed.

Further lowering the minimum required number of items, however, resulted in sharply

diminishing returns in terms of sample size. The total number of respondents satisfying the

resulting requirements was N = 1403 (38.7%).

Questionnaire

The questionnaire started with a screening question asking respondents whether they had

ever had an experience of “pure awareness.” Those answering yes were presented with the

full questionnaire including some demographic and personal questions as well as the 92

questionnaire items (“MPE items”). They were instructed to select, and then focus on, only

one single, particular experience of pure awareness that they had had and to answer all MPE

items with regard to that particular experience. If several experiences were eligible, participants

were asked to select "one in which the quality of pure awareness was particularly salient

and/or one which you can remember particularly clearly". To avoid time-based response

effects, presentation order of the items was randomized. At the end of the survey, participants

were also asked to supply a phenomenological report about any of their experiences of

pure awareness.

Respondents who had never had the requisite experience or who stated they did not

understand what we meant by "pure awareness" were asked to complete only the demographic

part of the survey. The demographic questions included biological sex, age, native

language, nationality, country of residence, frequency and duration of meditation practice,

meditation techniques, religious denomination, substance use and presence/absence of a

psychiatric diagnosis.

The core of the questionnaire consisted of the 92 MPE items addressing facets of the experience

of pure awareness that had previously been identified (by TM) in a comprehensive review

of the literature and with the help of advanced practitioners who mostly belonged to the Vipassana

and Zen traditions (similar to the final study sample, see Table 1). For example, there

were items on wakefulness, mood, state of relaxation, presence of thoughts, emotions or

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Table 1. Demographic and other participant information.

Analysis sample % missing

N 1403 0

Median (IQR, min–max) %

Age 52 (22, 17–88) .6

N (%) %

Sex 1.4

male 681 (48.5)

female 702 (50.0)

Chosen questionnaire language 0

German 889 (63.4)

English 440 (31.4)

Spanish 30 (2.1)

Italian 26 (1.9)

French 18 (1.3)

Native languagea 1.4

German 860 (61.3)

English 215 (15.3)

Dutch 55 (3.9)

Spanish 38 (2.7)

Italian 36 (2.6)

French 22 (1.6)

Russian 13 (.9)

Swedish 13 (.9)

Polish 11 (.8)

Hindi 10 (.7)

Portuguese 10 (.7)

Other 100 (7.1)

Country of residence 1.1

Germany 777 (55.4)

USA 110 (7.8)

Switzerland 87 (6.2)

Netherlands 63 (4.5)

United Kingdom 63 (4.5)

Italy 28 (2.0)

Austria 25 (1.8)

Australia 19 (1.4)

France 18 (1.3)

Canada 16 (1.1)

Spain 15 (1.1)

India 13 (0.9)

Sweden 12 (0.9)

Belgium 10 (0.7)

Denmark 10 (0.7)

Nepal 10 (0.7)

Other 112 (8.0)

Nationality 1.2

Germany 786 (56.0)

USA 103 (7.3)

(Continued)

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Table 1. (Continued)

Analysis sample % missing

Switzerland 84 (6.0)

United Kingdom 59 (4.2)

Netherlands 57 (4.1)

Italy 38 (2.7)

Austria 24 (1.7)

Australia 17 (1.2)

India 16 (1.1)

France 15 (1.1)

Sweden 15 (1.1)

Canada 14 (1.0)

Spain 13 (0.9)

Other 145 (10.3)

Meditation experience

Regular meditators 1085 (77.3) 1.3

Median (IQR, min–max)

Years meditating 10 (21, 0–55) 5.2

Sessions per day 1 (1, 0–60) 6.8

Minutes per session 30 (20, 1–240) 9.9

Meditation techniquea 2.7

Vipassana 616 (43.9)

Other 603 (43.0)

Zen 490 (34.9)

Metta 399 (28.4)

Mahamudra/Dzogchen 275 (19.6)

MBSR 274 (19.5)

Shamata 272(19.4)

TM 192 (13.7)

N of meditation techniques practiced 2.7

1 558 (39.8)

2 280 (20.0)

3 253 (18.0)

4 176 (12.5)

5 67 (4.8)

6 17 (1.2)

7 9 (.6)

8 5 (.4)

Substance usea 2.3

None 1161 (82.8)

Cannabis 123 (8.8)

Psychedelics 96 (6.9)

Other 46 (3.3)

Entactogens / MDMA 37 (2.6)

Stimulants 25 (1.8)

Anesthetics or Dissociatives 13 (.9)

Sedatives / Tranquilizers 13 (.9)

Opiates 4 (.3)

GHB / GBL 2 (.1)

(Continued)

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sensory perceptions, presence of a sense of self and the experience of time, to name just a few.

The full list of items can be found in Table 6.

MPE items were answered on a visual analogue scale ranging from 0 to 100, indicating the

degree to which a particular facet of experience was present. In practice, respondents used

their computer mouse to position a slider on a horizontal line (the slider defaulted to the midpoint

of the line). Scale endpoints were given labels appropriate to the form of each question.

Not all items therefore had the same response labels. In questions about the presence and

intensity of a particular phenomenal state (e.g. “Was there a sense of self?” or “Did you have a

visual experience of brightness with closed eyes?”), scale anchors were “No” on the left end

and “Very much so” or “Very strongly” on the right end. In questions about the presence and

frequency of certain countable experiential elements (e.g. “Did you have thoughts?” or “Did

you have memories?”) the label changed to “Very many” on the right end. Occasionally, there

were still other response labels when an item required it (e.g. the question “How alert were

you” had the anchors 0 = “unconscious”, 50 = “normal daytime alertness” and 100 = “much

more alert than normal”).

Although items were presented in a form answerable on a continuous scale, not all items

lent themselves to this approach equally well. For some, dichotomous “yes” / “no” anchors

seemed most appropriate, although even in these cases, a continuous degree of affirmability was

assumed to exist between the binary end points. Example questions include “Did you know that

you would be able to deliberately think thoughts if you wanted to?” and “Would it be a good

description to say that your experience of pure awareness, upon self-recognizing, also recognized

itself as that awareness which had always been present in all experiences in the past?”.

To maximize the number of complete answers, items were “soft-required,” i.e. when

skipped deliberately or accidentally, a pop-up message reminded respondents to provide an

answer if possible. A strict response enforcement was considered counterproductive, as

respondents might legitimately find it hard or even impossible to answer certain questions.

Table 1. (Continued)

Analysis sample % missing

Psychiatric diagnosis 1.1

Yes 90 (6.4)

No 1297 (92.4)

Religious denominationa 1.6

"Spiritual but not religious" (SBNR) / "Spiritual but not affiliated" (SBNA) 639 (45.6)

Buddhist 322 (23.0)

Christian 320 (22.8)

Secular 188 (13.4)

Other 72 (5.1)

Hindu 33 (2.4)

Jewish 7 (.5)

Muslim 4 (.3)

Median (IQR, min–max)

Importance of meditation (0–100) 90 (23, 0–100) 4.1

Importance of religion (0–100) 50 (78, 0–100) 10.1

aMultiple responses were possible. Percentages do not sum to 100%.

IQR = Interquartile Range, max = maximum, MBSR = Mindfulness-Based Stress Reduction, min = minimum,

N = Number, TM = Transcendental Meditation.

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The first 1000 respondents to completely answer all questions were offered a monetary

reward of € 50. The money was transferred using the web service Transferwise. Interested participants

were asked to leave a valid email address, as this was all the service required.

The questionnaire contained one control item (#66), which was a near-duplicate of another

item (#42) about the non-visual experience of "radiance". It was included to provide a sense of

the reliability of item responses.

Translations

Five different language versions of the MPE-92M exist. The original version was developed in

English and subsequently translated into German, French, Italian and Spanish. To create the

translations, a bilingual speaker translated from the English original into a second language,

and then translated back into English. The original and back-translated English versions were

then compared, and adjustments were made if necessary. In some cases, this process required

several iterations.

Statistics

Bartlett’s test for sphericity (p < 0.001) and the Kaiser-Meyer-Olkin Measure of Sampling

Adequacy (.94) confirmed the basic suitability of the data for factor analysis. Due to non-normality

of item distributions, exploratory factor analysis (EFA) was performed on Spearman

correlations using principal-factor estimation. Missing values were deleted pairwise, and the

average number of participants available across all pairwise correlations (N = 1393) was specified

for factor analysis. Loadings were rotated obliquely by the quartimin method in order to

allow for correlated factors. Theoretical and conceptual considerations as well as several statistical

methods were used to guide the number of factors to be extracted. These methods

included the scree plot, the Kaiser criterion (eigenvalue > 1), Horn’s parallel analysis, Velicer’s

MAP criterion and the Bayesian Information Criterion (BIC). Only items with primary loadings

of 0.3 or higher were assigned to their corresponding factors.

To explore the fit of the EFA solution, exploratory factor analysis in the context of confirmatory

factor analysis (E/CFA) was performed. The strongest-loading items per factor were

defined as anchor items whose cross-loadings were fixed at zero, while all other items were

allowed to freely load on all factors. A further identification constraint was to fix factor variances

at unity. E/CFA produces a saturated solution for the loading structure, so that modification

indexes are available only for error covariances. Correlated errors were tentatively allowed

when indicated by modification indexes corresponding to standardized expected parameter

changes of   0.2. Confirmatory factor analysis (CFA) was performed only to assess the fit of

any potential E/CFA solution, on which simple structure was imposed by constraining each

item to load exclusively on its primary factor. Again, factor variances were set to 1 to allow

identification. Internal consistencies per factor were calculated using Cronbach’s alpha.

We refrain from presenting an “optimized” short-form version of the questionnaire.

Although popular, attempts to construct and evaluate a reduced item pool in a dataset resulting

from the larger original item pool are in general methodologically unsound and have been

strongly advised against [13–15].

Fit indexes were interpreted according to recommendations in Brown [16]. Absolute fit

was assessed by the standardized root mean square residual (SRMR) and the root mean square

error of approximation (RMSEA). The SRMR indicates the average discrepancy between

observed and model-predicted item correlations. The RMSEA indicates deviations of the fitting

function from perfect fit and incorporates a penalty for lack of model parsimony. Relative

fit was assessed by the comparative fit index (CFI) and the Tucker-Lewis index (TLI). The CFI

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compares a given model to a baseline model that specifies no correlations between items. The

TLI is similar to the CFI, but again includes a penalty for lack of model parsimony. The following

values were considered to be consistent with good fit: SRMR   .08, RMSEA   .05, CFI

and TLI   .95. To account for non-normality in the data, computations of model fit were

repeated using quasi maximum likelihood (QML) estimation and the Satorra-Bentler correction

[17]. Analyses were performed in Stata 14.2 for Mac [18].

Results

Demographics of analysis sample (N = 1403)

Participants’ mean age was 52 years. The sample was nearly equally split between men and

women (48.5% vs 50.0%). The questionnaire language chosen most frequently was German

(63.4%), followed by English (31.4%). Correspondingly, German was the most frequently

reported native language (61.3%), again followed by English (15.3%). A total of 57 nations

were represented among participants. Regular meditators constituted the majority (77.3%) of

the sample. The most frequently named religious affiliation was “Spiritual but not religious” /

“Spiritual but not affiliated.” Substance use and psychiatric diagnoses were nearly absent.

Complete demographic information is shown in Table 1.

Distribution of meditation techniques

Overall, Vipassana was the most frequently named meditation technique (over 600 reports).

As shown in Fig 1, the single most frequent constellation of techniques was "other" (235 participants),

exclusive Zen meditation (138 participants), and exclusive TM (97 participants).

Comparing respondent groups: Those with vs. those without an experience

of pure awareness

A total of 2466 participants answered the screening question. The vast majority (91.5%,

N = 2257) reported having had at least one experience of pure awareness. In multivariable

regression, speaking German or Spanish as well as every additional ten years of meditation

practice increased the likelihood of a positive response by 2–5%. Being male reduced the likelihood

of a positive response by 4% (Table 2).

Comparing respondent groups: Those with an experience of pure

awareness vs. those not understanding the concept of pure awareness

3.2% (N = 78) of participants reported not understanding the concept of pure awareness. In

multivariable analysis, speaking German and practicing Mahamudra/Dzogchen were the only

statistically significant predictors of understanding and experiencing pure awareness compared

to not understanding it. Again, effects were small, raising the likelihood by 3% (Table 3).

Comparing respondent groups: Those included vs those not included in

factor analysis

Inclusion in the final analysis sample required at least one experience of pure awareness and a

nearly complete set of MPE items (at least 86 out of 92 items). 1403 participants met these

requirements, while 2264 did not. In multivariable analysis, regular meditation, every additional

ten years of meditation practice, speaking German and practicing Shamata, Zen or

some "other", unlisted meditation technique increased the likelihood of being included in factor

analysis by 3–9%. Being male reduced the likelihood by 7% (Table 4).

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Reliability: Control item

In about half of the 1403 participants, scores on the two almost identical items 42 and 66

diverged by 10 or less (Fig 2), with possible differences ranging from 0 to 100.

MPE items: Descriptive analysis

MPE items were generally non-normally distributed. Responses tended to cluster at the

extreme ends of the scale (Fig 3). The highest average ratings were given to items related to

wellbeing and relaxation; the overall lowest rating concerned the presence of pain during the

experience.

Exploratory factor analysis

The number of participants available for factor analysis was 1393. This number is an average

over the number of participants available for each pairwise item correlation, which ranged

Fig 1. Combinations of meditation techniques. Upset plot showing the combinations of meditation techniques occurring in the analysis sample (N = 1403). The

top graph is a histogram, with each bar representing the frequency of a particular (constellation of) meditation technique(s) that is/are identified right below it. Black

dots connected by black lines string together meditation techniques that belong to a given constellation. The bar chart on the left shows the overall frequencies of

each meditation technique.

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from 1357 to 1403. Fig 4 shows factor solutions with 6 to 12 factors obtained by oblique

rotation.

Different statistical criteria for the optimal number of factors yielded different recommendations.

While a scree plot suggested a 4- or 5-factor solution, Velicer’s MAP criterion and the

Kaiser “eigenvalue > 1” rule suggested 9 factors, Horn’s parallel analysis suggested 13 factors

and the Bayesian Information Criterion (BIC) was optimal at 14 factors. The latter, however, is

computed by maximum likelihood estimation under the assumption of multivariate normality,

which does not obtain in our data (see Fig 3).

From a conceptual and theoretical point of view, a solution with fewer than 6 factors was

deemed not sufficiently fine-grained to discriminate between what we considered to be clearly

distinct phenomenological aspects of MPE. A 12-factor solution, based on a loading threshold

of 0.3, was finally chosen as providing an optimal balance between conceptual resolution and

robustness of factors in terms of the number of supporting items.

The factors were named “Time, Effort and Desire,” “Peace, Bliss and Silence,” “Self-Knowledge,

Autonomous Cognizance and Insight,” “Wakeful Presence,” “Pure Awareness in Dream

and Sleep,” “Luminosity,” “Thoughts and Feelings,” “Emptiness and Non-egoic Self-awareness,”

“Sensory Perception in Body and Space,” “Touching World and Self,” “Mental Agency”

and “Witness Consciousness.” Internal consistencies ranged between 0.52 and 0.82, with a

Table 2. Risk ratios comparing participants with (N = 2257) and without (N = 131) an experience of pure awareness.

Unadjusted Risk Ratio [95% C.I.]a Adjusted Risk Ratio [95% C.I.]b % missing

pure awareness (N = 2257) no pure awareness (N = 131)

Age (10-year units) 1.02 [1.01–1.02]    1.00 [0.99–1.01] 16.0 11.5

Male sex 0.94 [0.92–0.96]    0.96 [0.94–0.98]    16.2 12.2

Meditates regularly 1.03 [1.00–1.06]  1.02 [0.99–1.04] 19.6 19.1

Years of practice (10-year units) 1.02 [1.01–1.03]    1.02 [1.01–1.03]    23.0 31.3

Questionnaire language 0 0

English 0.96 [0.93–0.98]    N.A.c

French 0.94 [0.83–1.07] 0.96 [0.84–1.11]

German 1.04 [1.02–1.06]    1.04 [1.01–1.07]  

Italian 1.00 [0.94–1.07] 1.01 [0.93–1.10]

Spanish 1.03 [0.98–1.07] 1.05 [1.00–1.10] 

Meditation technique 21.9 29.0

Mahamudra/Dzogchen 1.01 [0.99–1.04] 1.00 [0.97–1.03]

MBSR 1.03 [1.01–1.05]  1.02 [1.00–1.04]

Metta 1.01 [0.98–1.03] 1.00 [0.97–1.02]

Shamata 1.03 [1.00–1.05]  1.02 [0.99–1.05]

TM 1.03 [1.00–1.05]  1.00 [0.97–1.03]

Vipassana 1.01 [0.99–1.03] 1.01 [0.98–1.03]

Zen 1.01 [0.99–1.03] 1.00 [0.98–1.02]

Other 1.03 [1.01–1.05]   1.02 [1.00–1.04]

aUnivariable general linear regressions with Gaussian distribution, log link and robust standard errors, variable N (1827–2388).

bMultivariable general linear regression with Gaussian distribution, log link and robust standard errors, N = 1750.

cEnglish is the reference category.

 p < .05,

  p < .01,

   p < .001.

N.A. = not applicable.

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mean of 0.72. Nine out of 12 factors had consistencies of   0.70. Table 5 shows factor names,

the proportion of explained variance per factor, and internal consistencies.

Table 6 shows item-to-factor assignments, factor loadings, factor names and item uniqueness

of the 12-factor solution. Uniqueness values, which represent unique, non-shared item

variance, were relatively high, with 32 (35%) of 92 items above 0.6. Correspondingly, total variance

explained by common factors was at a moderate 44%.

Factor correlations, which are a consequence of oblique rotation, are shown in Table 7.

Confirmatory factor analysis

Overall, model fit of the solution from exploratory factor analysis (EFA) was moderate to

acceptable, but significantly degraded after imposing simple structure in a confirmatory factor

analysis (CFA).

A reproduction of the 12-factor solution using EFA in the context of CFA produced a moderate

fit to the data: while absolute fit indexes were consistent with good fit (RMSEA = .034,

90% CI = [.033–.035]; p(RMSEA   .05) = 1.0; SRMR = .025), comparative fit was weak (CFI =

.875; TLI = .834). Using the Satorra-Bentler correction slightly improved fit (RMSEA = .030;

Table 3. Risk ratios comparing participants with an experience of pure awareness (N = 2257) to those not understanding the concept of pure awareness (N = 78).

Unadjusted Risk Ratio [95% C.

I.]a

Adjusted Risk Ratio [95% C.

I.]b

% missing

pure awareness

(N = 2257)

did not understand concept

(N = 78)

Age (10-year units) 1.00 [1.00–1.01] 0.99 [0.98–1.00] 15.6 20.5

Male sex 0.99 [0.97-.1.01] 0.99 [0.98–1.01] 16.2 19.3

Meditates regularly 1.02 [1.00–1.05]  1.02 [0.99–1.04] 19.6 21.8

Years of practice (10-year

units)

1.00 [1.00–1.01] 1.01 [1.00–1.01] 23.0 30.8

Questionnaire language 0 0

English 0.98 [0.96–0.99]   N.A.c

French 0.99 [0.92–1.07] 0.99 [0.89–1.11]

German 1.03 [1.01–1.04]   1.03 [1.01–1.06]   

Italian 1.00 [0.95–1.05] 1.01 [0.93–1.08]

Spanish 0.97 [0.92–1.03] 1.03 [0.98–1.07]

Meditation technique 21.9 35.9

Mahamudra/Dzogchen 1.01 [1.00–1.0] 1.03 [1.00–1.05] 

MBSR 1.00 [0.98–1.02] 1.00 [0.98–1.02]

Metta 1.00 [0.99–1.02] 1.01 [0.99–1.03]

Shamata 0.99 [0.97–1.02] 0.99 [0.96–1.01]

TM 1.01 [0.99–1.03] 1.00 [0.98–1.03]

Vipassana 0.99 [0.98–1.01] 0.99 [0.97–1.01]

Zen 1.00 [0.99–1.02] 1.00 [0.99–1.02]

Other 1.01 [1.00–1.03] 1.01 [1.00–1.03]

aUnivariable general linear regressions with Gaussian distribution, log link, and robust standard errors, variable N (1791–2335).

bMultivariable general linear regression with Gaussian distribution, log link, and robust standard errors, N = 1717.

cEnglish is the reference category.

 p < .05,

  p < .01,

   p < .001.

N.A. = not applicable.

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SRMR = .025; CFI = .887; TLI = .849). Model fit improved more noticeably after allowing correlated

errors as indicated by modification indexes corresponding to expected parameter

changes of   .2: RMSEA = .025, 90% CI = [.023–.026]; p(RMSEA   .05) = 1.0; SRMR = .022;

CFI = .935; TLI = .913. Applying the Satorra-Bentler correction further improved fit very

slightly: RMSEA = .021; SRMR = .022; CFI = .946; TLI = .928.

After imposing simple structure by suppressing cross-loadings, model fit decreased substantially.

While absolute fit was still acceptable (RMSEA = .053, 90% CI = [.052–.054]; p

(RMSEA   .05) = 0.00; SRMR = .075), comparative fit was very weak (CFI = .707; TLI = .690).

Comparative fit improved marginally after applying the Satorra-Bentler correction (CFI =

.715; TLI = .699). Allowing correlated errors as indicated by modification indexes corresponding

to expected parameter changes of   .2 improved the model, but comparative fit remained

weak (RMSEA = .004, 90% CI = [.039–.041]; p(RMSEA   .05) = 1.0; SRMR = .060; CFI = .840;

TLI = .826). Marginal improvement resulted from applying the Satorra-Bentler correction

(RMSEA = .036; SRMR = .060; CFI = .849; TLI = .836).

Phenomenological reports

A total of 1171 reports about experiences of pure awareness were submitted, of which 841

were usable. These will undergo a qualitative analysis, to be published separately.

Table 4. Risk ratios comparing participants included (N = 1403) to those not included (N = 2224) in factor analysis.

Unadjusted Risk Ratio [95% C.I.]a Adjusted Risk Ratio [95% C.I.]b % missing

included in FA (N = 1403) excluded from FA (N = 2224)

Age (10-year units) 1.04 [1.02–1.06]    0.99 [0.96–1.01] 0.6 68.4

Male sex 0.94 [0.88–1.00]  0.93 [0.87–0.99]  1.4 68.2

Meditates regularly 1.13 [1.05–1.22]    1.08 [1.00–1.17]  1.3 72.2

Years of practice (10 year units) 1.04 [1.02–1.06]    1.03 [1.00–1.06]  5.2 74.4

Questionnaire language 0 0

English 0.88 [0.80–0.96]   N.A.c

French 0.86 [0.59–1.26] 1.20 [0.98–1.46]

German 1.17 [1.08–1.28]    1.09 [1.02–1.17] 

Italian 1.00 [0.74–1.36] 0.88 [0.68–1.15]

Spanish 0.76 [0.56–1.03] 0.90 [0.71–1.14]

Meditation technique 2.7 74.7

Mahamudra/Dzogchen 1.05 [0.98–1.12] 1.03 [0.96–1.11]

MBSR 1.03 [0.96–1.10] 1.02 [0.95–1.10]

Metta 1.03 [0.96–1.09] 1.01 [0.94–1.18]

Shamata 1.09 [1.02–1.27]  1.09 [1.01–1.18] 

TM 1.07 [0.99–1.15] 1.06 [0.97–1.15]

Vipassana 1.01 [0.96–1.07] 1.02 [0.96–1.10]

Zen 1.06 [1.00–1.12]  1.08 [1.02–1.14] 

Other 1.06 [1.00–1.12] 1.08 [1.02–1.15]  

aUnivariable general linear regressions with Gaussian distribution, log link and robust standard errors, variable N (1900–3627).

bMultivariable general linear regression with Gaussian distribution, log link and robust standard errors, N = 1814.

cEnglish is the reference category.

 p < .05,

  p < .01,

   p < .001.

FA = factor analysis, N = number, N.A. = not applicable.

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Discussion

The experience of “pure awareness” has been reported and described in the literature on contemplative

practices since at least around the 8th to 6th century BCE ([19], p39). In this study,

we attempted a first phenomenological characterization of such experiences using a 92-item

online questionnaire distributed among meditators. Over 1400 responses were gathered and

factor-analyzed. The preferred solution contained 12 factors accounting for a moderate 44% of

the total variance, with unique item variances being relatively large. Therefore, the chosen

solution is likely to leave some of the questionnaire’s phenomenological and semantic content

as well as survey response patterns unexplained. In line with this, reproducing the 12-factor

solution in the context of a confirmatory factor analysis resulted in a moderate-to-acceptable

fit to the data, while imposing simple structure produced an ill-fitting solution. It is clear that

the chosen factor solution will not fit the present data well without allowing for a significant

amount of cross-loading.

With these limitations in mind, we now give possible interpretations of the 12 factors in

terms of their phenomenology and our background theory. We also make connections to how

this phenomenology may typically manifest in meditative practice. The interpretations and

connections we propose are predicated on the assumption that these factors or very similar

ones may be reproduced in future studies, which is by no means guaranteed. However, such

speculation may be fruitful for future research by giving rise to new testable hypotheses concerning

the phenomenal structure of pure awareness experiences.

Factor 1 ("Time, Effort and Desire") bundles experiential aspects of a process that could be

described as “dual mindfulness.” Phenomenologically, there is still a meditator and a goal

state, there is a sense of effort created by either mental or bodily agency, and accordingly the

subjective experience of time emerges. Factor 1 points to the conscious experience of a process

that is still goal-directed (there is a desire), and in which there is a sense of effort (for example,

in controlling body posture, or in the subjective experience of repeatedly bringing attention

back to the breath or other objects of meditation, as in Shikantaza, in Shamatha practice or in

Fig 2. Distribution of difference between control items. Distribution of differences in item scores between two

almost identically worded questions (#42 and #66) asking about the presence of a non-visual experience of "radiance".

Item scores range from 0–100, so that the maximum possible difference is 100. N = 1403.

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other forms of focussed-attention meditation). Typically, there will be an attentional lapse, followed

by the phenomenology of noticing, remembering the goal state and re-focussing [20,

21]. As a result, temporal experience is preserved: for example, we find the phenomenology of

duration and of time passing. There may already be an experience of awareness as such, but

this is still a meditation experience, not yet effortless and not a full-absorption episode. (A

“full-absorption episode” is defined as an experience in which MPE is the only kind of phenomenal

character that can later be reported, i.e., a phenomenal state in which the experiential

Fig 3. Distribution of questionnaire items. Statistical distribution of questionnaire items in analysis sample

(N = 1403). Dots indicate medians.

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Fig 4. Results of exploratory factor analysis of the MPE-92M questionnaire (N = 1393). Questionnaire items are

listed on the y-axis. Each column corresponds to a full factor solution with the number of extracted factors given on

the x-axis. The size (area) of the circles is proportional to the factor loadings. Open circles indicate negative loadings,

and loadings below 0.3 are not shown. Color represents factor membership. An attempt was made to identify the

"same" factors across all factor solutions and color them identically. “Sameness” here is not objectively definable, but

the degree of similarity was operationalized as membership in the same cluster following hierarchical cluster analysis.

Items are sorted by factor membership and size of factor loading in the 12-factor solution, as it was this solution that

was finally chosen as optimal.

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quality of “pure consciousness” is the only one that is later available for memory and verbal

report).

Factor correlations show that “Time, Effort and Desire” is negatively correlated with

“Peace, Bliss and Silence” (Factor 2) and “Emptiness and Non-egoic Self-awareness” (Factor

8). This makes good phenomenological sense, because these factors express deep relaxation,

existential ease, a sense of wholeness, positive affect and the atemporal, non-dual and selfless

quality of “pure knowing” (see below). “Time, Effort and Desire” is positively correlated with

the arising of thoughts and feelings, with mind-wandering, discursive thought and different

forms of mental time travel (Factor 7) and also with the noticing of perceptual content arising

(Factor 9). Our data and a qualitative assessment of verbal reports (to be published in a separate

monograph) show how, in a large sample, even experienced meditators and committed

practitioners have varied experiences, including frequent attentional lapses and other banal or

commonplace states. This point also relates to the existence of very short spontaneous occurrences

of MPE in everyday life, and to the micro-meditative technique of “glimpsing” outside

of formal practice, in both of which states of pure consciousness are sandwiched by longer

periods of more ordinary phenomenology. All of this is part of a normal meditation experience,

and to be expected.

What we have defined as “dual mindfulness” (i.e., a process in which there is still a meditator,

a goal state, a sense of effort, and the subjective experience of time) is directly related to a

specific semantic constraint for the concept of MPE which was extracted from the existing literature

in an earlier study, namely “Introspective Availability” (PC4; cf. [9]; section 2.2.1). One

traditional assumption, extensively discussed in Eastern as well as in Western philosophy of

mind, is that we can sometimes actively direct introspective attention to the quality of consciousness

per se. If this turns out to be correct, then one can distinguish different states by the

degree of actually ongoing introspective access to precisely this quality.

Factor 2 ("Peace, Bliss and Silence") picks out the experience of relaxation and ease, which

is perhaps the best-known effect of meditation practice generally. This factor also refers to a

simple experience of deep, unbounded silence (cf. [22]) and “pure being”, which is described

as natural and gentle. The two items relating to the phenomenal experience of “peace” and

Table 5. Factor names and explained variance per factor.

Factor number Factor name % explained variancea Internal consistencyb

1 Time, Effort and Desire 27 0.79

2 Peace, Bliss and Silence 25 0.82

3 Self-Knowledge, Autonomous Cognizance and Insight 16 0.70

4 Wakeful Presence 15 0.67

5 Pure Awareness in Dream and Sleep 15 0.52

6 Luminosity 14 0.76

7 Thoughts and Feelings 13 0.81

8 Emptiness and Non-egoic Self-awareness 13 0.65

9 Sensory Perception in Body and Space 12 0.71

10 Touching World and Self 12 0.72

11 Mental Agency 9 0.74

12 Witness Consciousness 7 0.82

aFactors after oblique rotation are correlated and therefore account for overlapping portions of total item variance. Proportions of explained variance therefore cannot

be summed up across factors. Instead, the total explained variance of the entire factor solution can be obtained as average item communality, which was 44%.

bCronbach’s alpha.

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Table 6. Factor membership and loadings of MPE items in 12-factor solution (with color coding corresponding to Fig 4).

Factor

1

Factor

2

Factor 3 Factor 4 Factor 5 Factor 6 Factor 7 Factor 8 Factor 9 Factor 10 Factor

11

Factor 12 Uniqueness

Item

Nr

Item long name Time,

Effort

and

Desire

Peace,

Bliss

and

Silence

Self-

Knowledge,

Autonomous

Cognizance

and Insight

Wakeful

Presence

Pure

Awareness

in Dream

and Sleep

Luminosity Thoughts

and

Feelings

Emptiness

and Nonegoic

Selfawareness

Sensory

Perception

in Body and

Space

Touching

World and

Self

Mental

Agency

Witness

Consciousness

25 Did you

experience the

passage of time?

0.76 -0.05 0.00 0.00 -0.02 0.02 -0.01 0.01 0.09 -0.02 0.01 0.03 0.34

24 Did you

experience the

duration of time

as such?

0.73 -0.01 0.00 0.04 0.00 0.01 0.01 0.00 0.04 0.00 -0.06 0.04 0.45

22 Did you

experience time?

0.73 -0.02 -0.01 -0.04 -0.02 0.00 0.00 -0.07 0.08 -0.03 0.01 0.01 0.35

36 Was there a sense

of effort?

0.44 -0.21 -0.14 -0.06 0.10 0.03 0.14 0.08 -0.02 0.02 0.05 0.11 0.43

38 Did you have any

desires?

0.37 -0.14 -0.07 -0.10 0.12 0.01 0.28 -0.01 0.07 0.03 0.03 0.08 0.40

33 Did you have a

sense of bodily

agency, in terms

of actively and

deliberately

controlling your

body

movements?

0.36 -0.11 -0.10 0.08 0.03 0.00 0.09 0.02 0.21 0.02 0.24 0.02 0.52

35 Did you have a

sense of mental

agency, in terms

of actively and

deliberately

thinking

thoughts?

0.28 -0.09 -0.14 -0.03 0.05 -0.04 0.28 0.02 0.05 0.03 0.24 0.07 0.49

17 Was there pain? 0.28 -0.18 0.06 -0.16 0.25 -0.02 0.10 0.10 0.10 0.12 0.05 0.00 0.54

59 Did you

experience the

space of pure

awareness as

having

boundaries?

0.27 -0.20 -0.16 0.00 0.18 -0.07 -0.04 -0.24 0.03 0.14 0.01 0.04 0.49

57 Did your

experience have a

quality that could

be described as a

non-physical

“space”?

-0.23 0.15 0.19 0.00 -0.01 0.19 0.04 0.21 -0.06 0.04 0.07 0.04 0.59

(Continued)

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Table 6. (Continued)

Factor

1

Factor

2

Factor 3 Factor 4 Factor 5 Factor 6 Factor 7 Factor 8 Factor 9 Factor 10 Factor

11

Factor 12 Uniqueness

Item

Nr

Item long name Time,

Effort

and

Desire

Peace,

Bliss

and

Silence

Self-

Knowledge,

Autonomous

Cognizance

and Insight

Wakeful

Presence

Pure

Awareness

in Dream

and Sleep

Luminosity Thoughts

and

Feelings

Emptiness

and Nonegoic

Selfawareness

Sensory

Perception

in Body and

Space

Touching

World and

Self

Mental

Agency

Witness

Consciousness

60 Did you

experience the

space of pure

awareness as

divisible?

0.22 -0.17 -0.15 -0.08 0.17 -0.02 0.01 -0.11 0.02 0.22 0.00 0.05 0.60

29 Was your

experience part

of your own

inner life?

0.20 0.15 -0.01 0.16 0.15 -0.01 0.10 -0.18 -0.12 0.11 0.15 0.07 0.76

71 Did you feel

relaxed?

-0.05 0.76 0.04 -0.01 -0.01 0.01 -0.01 -0.01 -0.03 -0.07 0.03 0.01 0.37

69 Did you feel at

peace?

-0.03 0.72 -0.04 0.02 -0.09 0.01 -0.02 0.05 -0.03 -0.02 0.02 -0.05 0.38

70 Did you feel at

ease?

-0.01 0.72 0.02 0.03 -0.09 0.04 -0.01 -0.01 -0.02 -0.07 0.02 -0.08 0.37

68 Did you feel

whole?

-0.14 0.54 0.13 0.09 0.00 0.02 0.04 0.02 0.01 0.07 0.02 -0.07 0.44

65 Was there a

subtle but clearly

positive mood,

e.g. like an

"invisible smile"?

-0.06 0.47 -0.05 0.02 -0.15 0.17 0.07 -0.14 0.04 0.21 0.07 0.02 0.53

64 Did your

experience have a

quality of

"blissfulness"?

-0.02 0.45 -0.09 0.11 -0.10 0.23 0.21 -0.02 -0.02 0.18 -0.05 0.00 0.49

67 Did your

experience have a

quality of deep,

unbounded

silence?

-0.02 0.42 0.02 0.02 0.02 0.01 -0.04 0.30 -0.19 0.06 -0.02 0.06 0.52

73 Did you have a

sense that the

state you

experienced was

“the natural

state”?

-0.03 0.40 0.34 0.03 0.03 0.05 -0.03 0.08 -0.03 0.03 0.05 0.02 0.53

63 Did your

experience have a

quality of nontactile

and nonemotional

"gentleness"?

0.04 0.39 0.00 -0.11 -0.02 0.13 -0.17 0.05 -0.04 0.33 0.08 0.06 0.60

(Continued)

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Table 6. (Continued)

Factor

1

Factor

2

Factor 3 Factor 4 Factor 5 Factor 6 Factor 7 Factor 8 Factor 9 Factor 10 Factor

11

Factor 12 Uniqueness

Item

Nr

Item long name Time,

Effort

and

Desire

Peace,

Bliss

and

Silence

Self-

Knowledge,

Autonomous

Cognizance

and Insight

Wakeful

Presence

Pure

Awareness

in Dream

and Sleep

Luminosity Thoughts

and

Feelings

Emptiness

and Nonegoic

Selfawareness

Sensory

Perception

in Body and

Space

Touching

World and

Self

Mental

Agency

Witness

Consciousness

55 Did you have an

experience of

“pure being”?

-0.06 0.34 0.17 0.26 0.04 0.01 -0.04 0.23 0.01 0.09 -0.03 -0.09 0.46

8 Was your mood

positive?

-0.05 0.32 -0.17 0.28 -0.12 0.18 0.21 -0.06 0.00 0.08 -0.02 -0.12 0.58

86 Is the experience

of pure

awareness the

simplest kind of

conscious

experience you

know?

0.04 0.31 0.23 -0.01 0.03 -0.03 -0.16 0.10 0.06 0.04 0.00 0.04 0.76

89 Did your

experience have a

quality of nonacoustic

"harmony" or

“soundness”?

-0.13 0.29 -0.01 0.08 -0.02 0.09 0.08 0.05 0.00 0.29 0.00 -0.20 0.60

52 Did the

experience have a

quality of

knowing itself?

0.11 0.05 0.46 0.16 -0.01 0.18 0.16 0.02 -0.13 0.05 0.08 0.06 0.56

46 Did your

experience have a

“cognizant”

quality?

-0.10 -0.06 0.42 0.19 -0.07 0.14 0.20 -0.04 -0.11 0.13 0.13 -0.11 0.54

44 Did your

experience have a

quality of

autonomy,

meaning that it

existed all by

itself; that it came

by itself and went

by itself; that it

was nothing you

had created?

-0.19 0.05 0.42 0.01 0.00 0.14 -0.08 0.03 0.07 -0.06 -0.18 0.06 0.59

75 Was there a

quality of

insight?

-0.04 0.03 0.38 0.12 -0.25 0.11 0.23 0.00 -0.03 0.16 0.02 0.06 0.54

(Continued)

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Table 6. (Continued)

Factor

1

Factor

2

Factor 3 Factor 4 Factor 5 Factor 6 Factor 7 Factor 8 Factor 9 Factor 10 Factor

11

Factor 12 Uniqueness

Item

Nr

Item long name Time,

Effort

and

Desire

Peace,

Bliss

and

Silence

Self-

Knowledge,

Autonomous

Cognizance

and Insight

Wakeful

Presence

Pure

Awareness

in Dream

and Sleep

Luminosity Thoughts

and

Feelings

Emptiness

and Nonegoic

Selfawareness

Sensory

Perception

in Body and

Space

Touching

World and

Self

Mental

Agency

Witness

Consciousness

54 Would it be a

good description

to say that your

experience of

pure awareness,

upon selfrecognizing,

also

recognized itself

as that awareness

which had always

been present in

all experiences in

the past?

0.01 0.07 0.37 0.03 -0.02 0.07 -0.03 0.14 -0.01 0.19 0.07 0.05 0.66

74 Did you have a

sense that the

state you

experienced was

nothing you had

fabricated?

-0.20 0.18 0.37 -0.06 -0.13 0.12 -0.02 0.08 0.07 -0.08 -0.09 0.17 0.54

41 Did your

experience have a

non-visual

quality of

“clarity”?

-0.08 0.11 0.31 0.23 -0.06 0.26 -0.08 0.06 -0.01 -0.06 0.06 -0.08 0.49

45 Was there an

experience of

“pure knowing”

without any

object?

0.02 0.09 0.29 0.17 0.08 0.23 -0.01 0.25 -0.19 -0.07 0.05 -0.03 0.56

82 Did you feel

identical to the

experience of

pure awareness

itself?

-0.07 0.19 0.26 0.19 -0.03 -0.04 -0.01 0.20 -0.01 0.12 -0.02 -0.11 0.59

77 Were you

looking not at

pure awareness,

but from pure

awareness?

-0.07 0.22 0.25 0.07 -0.08 0.01 -0.10 0.16 0.04 0.10 0.06 0.03 0.64

21 Did you have an

experience of

"now"?

0.05 0.03 0.11 0.57 -0.03 -0.03 -0.04 -0.11 -0.04 0.06 0.04 0.19 0.56

(Continued)

PLOS ONE “Pure awareness” in meditators: A fine-grained phenomenological analysis

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Table 6. (Continued)

Factor

1

Factor

2

Factor 3 Factor 4 Factor 5 Factor 6 Factor 7 Factor 8 Factor 9 Factor 10 Factor

11

Factor 12 Uniqueness

Item

Nr

Item long name Time,

Effort

and

Desire

Peace,

Bliss

and

Silence

Self-

Knowledge,

Autonomous

Cognizance

and Insight

Wakeful

Presence

Pure

Awareness

in Dream

and Sleep

Luminosity Thoughts

and

Feelings

Emptiness

and Nonegoic

Selfawareness

Sensory

Perception

in Body and

Space

Touching

World and

Self

Mental

Agency

Witness

Consciousness

20 Did you have an

experience of

"here"?

0.13 0.11 0.07 0.55 0.04 -0.15 -0.06 -0.18 0.10 0.10 -0.03 0.19 0.56

23 Did you

experience

yourself as being

in the present

moment?

-0.19 0.14 0.10 0.51 -0.04 -0.02 -0.05 0.04 0.04 -0.04 0.05 -0.05 0.47

2 How alert were

you?

-0.07 -0.08 -0.05 0.49 -0.16 0.20 -0.05 0.23 0.05 -0.08 0.11 -0.05 0.53

32 Did you have the

experience of

simply "being",

e.g. of simply

being here and

now?

-0.11 0.34 0.08 0.43 0.04 -0.08 -0.10 0.07 0.04 -0.05 0.02 -0.02 0.50

1 How awake were

you?

-0.02 -0.11 -0.01 0.43 -0.19 0.26 -0.09 0.22 0.02 -0.07 0.08 -0.07 0.55

15 Was there an

experience of

oneness or unity?

-0.17 0.13 0.08 0.32 -0.04 0.09 0.20 0.21 -0.03 0.14 -0.13 -0.04 0.51

56 Did you feel the

fact of your own

existence as

such?

0.07 0.16 0.24 0.24 0.09 0.00 0.01 -0.16 -0.09 0.14 0.11 0.00 0.72

83 Did your

experience occur

during dreamless

deep sleep?

-0.04 -0.07 0.03 0.01 0.72 0.05 -0.03 0.01 0.03 0.04 -0.04 0.05 0.46

84 Did your

experience occur

during the dream

state?

-0.07 -0.08 -0.02 0.05 0.70 0.08 0.02 -0.02 0.03 0.03 -0.04 0.04 0.48

85 Did your

experience occur

during the

normal awake

state, possibly

together with

thoughts and

sensations?

0.11 0.04 0.17 0.08 -0.31 -0.10 0.03 0.02 0.15 0.08 0.14 -0.09 0.78

(Continued)

PLOS ONE “Pure awareness” in meditators: A fine-grained phenomenological analysis

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Table 6. (Continued)

Factor

1

Factor

2

Factor 3 Factor 4 Factor 5 Factor 6 Factor 7 Factor 8 Factor 9 Factor 10 Factor

11

Factor 12 Uniqueness

Item

Nr

Item long name Time,

Effort

and

Desire

Peace,

Bliss

and

Silence

Self-

Knowledge,

Autonomous

Cognizance

and Insight

Wakeful

Presence

Pure

Awareness

in Dream

and Sleep

Luminosity Thoughts

and

Feelings

Emptiness

and Nonegoic

Selfawareness

Sensory

Perception

in Body and

Space

Touching

World and

Self

Mental

Agency

Witness

Consciousness

40 Did your

experience have a

non-visual

quality of

“brightness”?

0.02 -0.03 0.02 -0.03 0.04 0.73 -0.02 0.03 0.02 -0.02 0.02 -0.01 0.49

42 Did your

experience have a

non-visual

quality of

“radiance” or

"self-luminosity"?

0.09 0.03 0.13 0.02 0.05 0.69 -0.08 -0.03 0.00 0.07 -0.04 -0.02 0.45

66 Did your

experience have a

non-visual

quality of being

"radiant"?

0.02 0.18 0.07 -0.06 -0.06 0.58 -0.05 -0.04 0.04 0.15 -0.04 0.07 0.47

39 Did you have a

visual experience

of brightness

with closed eyes?

-0.06 0.04 -0.18 -0.05 0.20 0.53 0.26 0.04 -0.02 -0.05 0.00 0.08 0.57

62 Did your

experience have a

quality that could

be described as

“vibrant”, but in

a non-tactile and

non-visual sense?

-0.07 0.02 0.03 0.04 -0.11 0.37 0.00 -0.03 0.16 0.23 0.03 0.16 0.64

3 Did you have

thoughts?

0.17 -0.02 0.11 -0.13 0.02 -0.10 0.48 -0.12 0.18 -0.03 0.07 0.04 0.44

6 Did you have

mental images,

e.g. motor

imagery?

-0.10 0.01 0.03 -0.06 0.22 0.05 0.48 -0.07 0.22 0.01 0.01 0.05 0.56

7 Did you have

emotions?

0.07 0.01 -0.05 0.01 -0.02 0.09 0.44 -0.17 0.21 0.08 -0.09 -0.07 0.59

26 Were there

concepts in your

mind?

0.33 -0.09 0.13 -0.15 -0.01 -0.02 0.37 -0.09 0.09 -0.03 0.08 0.10 0.45

4 Did you have

spontaneously

occurring

memories?

0.13 0.07 0.07 -0.17 0.31 -0.07 0.37 0.09 0.12 0.12 0.07 0.01 0.49

(Continued)

PLOS ONE “Pure awareness” in meditators: A fine-grained phenomenological analysis

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Table 6. (Continued)

Factor

1

Factor

2

Factor 3 Factor 4 Factor 5 Factor 6 Factor 7 Factor 8 Factor 9 Factor 10 Factor

11

Factor 12 Uniqueness

Item

Nr

Item long name Time,

Effort

and

Desire

Peace,

Bliss

and

Silence

Self-

Knowledge,

Autonomous

Cognizance

and Insight

Wakeful

Presence

Pure

Awareness

in Dream

and Sleep

Luminosity Thoughts

and

Feelings

Emptiness

and Nonegoic

Selfawareness

Sensory

Perception

in Body and

Space

Touching

World and

Self

Mental

Agency

Witness

Consciousness

5 Were you

planning or

thinking about

the future?

0.23 0.02 0.07 -0.17 0.31 -0.06 0.35 0.05 0.08 0.06 0.04 -0.05 0.48

27 Was there

discursive

thought?

0.28 -0.05 -0.08 -0.23 0.08 -0.05 0.32 -0.01 0.04 -0.04 0.16 0.11 0.41

43 Did your

experience vary

in its intensity?

0.15 -0.01 -0.21 -0.12 0.03 0.01 0.25 0.06 0.08 0.02 0.13 0.12 0.68

13 Could your

experience be

described as

emptiness, a

vacuum, or a

void?

0.06 0.12 -0.10 0.03 0.11 0.00 -0.07 0.45 -0.21 0.09 -0.05 0.16 0.63

53 Would it be a

good description

to say that there

was “an

emptiness that

has awoken to

itself”?

0.13 0.11 0.14 0.04 0.03 -0.03 -0.09 0.39 -0.15 0.22 -0.01 0.12 0.62

51 Did you feel as

though it was not

you who had an

experience of

“pure knowing”

without any

object, it was

rather as if the

“pure knowing”

was self-aware,

knowing only

itself, while you

had nothing to

do with it?

0.00 -0.04 0.25 -0.05 -0.05 0.12 -0.13 0.38 0.04 0.07 -0.11 0.18 0.59

28 Was there a sense

of self?

0.24 0.08 -0.06 0.14 0.20 -0.04 0.24 -0.37 -0.06 0.00 0.14 0.01 0.49

(Continued)

PLOS ONE “Pure awareness” in meditators: A fine-grained phenomenological analysis

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Table 6. (Continued)

Factor

1

Factor

2

Factor 3 Factor 4 Factor 5 Factor 6 Factor 7 Factor 8 Factor 9 Factor 10 Factor

11

Factor 12 Uniqueness

Item

Nr

Item long name Time,

Effort

and

Desire

Peace,

Bliss

and

Silence

Self-

Knowledge,

Autonomous

Cognizance

and Insight

Wakeful

Presence

Pure

Awareness

in Dream

and Sleep

Luminosity Thoughts

and

Feelings

Emptiness

and Nonegoic

Selfawareness

Sensory

Perception

in Body and

Space

Touching

World and

Self

Mental

Agency

Witness

Consciousness

91 Did you

experience a

dissolving of the

boundary

between yourself

and your

surroundings?

For example, you

no longer knew

where our body

started and

ended, or you felt

like you were

either everything

or nothing?

-0.25 0.08 0.03 0.01 -0.12 0.01 0.16 0.36 0.00 0.14 -0.17 0.14 0.57

92 Did you have an

experience of

your breath

stopping? E.g., in

the sense that

you felt you no

longer had to

breathe?

-0.12 -0.03 -0.11 -0.04 0.18 0.07 0.04 0.28 -0.12 0.15 -0.02 0.19 0.74

72 Did you

experience the

state of pure

awareness as

neither mental

nor bodily?

-0.17 0.17 0.21 -0.15 0.05 0.07 -0.04 0.24 -0.06 0.07 -0.09 0.04 0.65

81 Is it possible for

you to put your

experience of

pure awareness

into words?

0.00 0.06 0.09 0.13 0.09 -0.02 0.03 -0.14 0.00 0.01 0.08 0.04 0.93

9 Did you have

perceptions, for

example of

objects in your

environment?

0.10 0.01 0.07 0.08 -0.06 -0.07 -0.12 0.02 0.60 0.01 0.06 0.04 0.61

19 Was there

motion in space?

0.12 -0.07 -0.01 0.08 0.10 0.10 0.03 0.08 0.53 0.04 -0.02 0.04 0.59

18 Did you have

movement

sensations?

0.12 -0.03 -0.06 0.01 0.13 0.00 0.10 -0.01 0.52 0.06 0.02 0.07 0.51

(Continued)

PLOS ONE “Pure awareness” in meditators: A fine-grained phenomenological analysis

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Table 6. (Continued)

Factor

1

Factor

2

Factor 3 Factor 4 Factor 5 Factor 6 Factor 7 Factor 8 Factor 9 Factor 10 Factor

11

Factor 12 Uniqueness

Item

Nr

Item long name Time,

Effort

and

Desire

Peace,

Bliss

and

Silence

Self-

Knowledge,

Autonomous

Cognizance

and Insight

Wakeful

Presence

Pure

Awareness

in Dream

and Sleep

Luminosity Thoughts

and

Feelings

Emptiness

and Nonegoic

Selfawareness

Sensory

Perception

in Body and

Space

Touching

World and

Self

Mental

Agency

Witness

Consciousness

16 Were there

sensory qualities,

e.g. brightness,

colour, sound,

taste, smell?

-0.12 -0.01 -0.04 0.05 0.00 0.25 0.12 -0.10 0.51 -0.05 0.04 0.03 0.62

12 Did you feel your

body if you did

not deliberately

attend to it?

0.25 0.03 -0.01 0.10 0.01 -0.11 -0.07 -0.15 0.37 0.09 0.10 -0.02 0.63

11 Did you have

temperature

sensations?

0.14 0.07 -0.08 -0.09 0.16 -0.02 0.14 0.07 0.35 0.12 0.03 0.02 0.63

14 Was awareness

itself the only

content of

awareness?

-0.11 0.06 0.00 0.19 0.15 -0.03 -0.21 0.18 -0.30 0.04 -0.04 -0.05 0.62

10 Did you have

weight

sensations?

0.13 0.00 -0.12 -0.08 0.17 -0.08 0.15 0.08 0.28 0.10 0.04 0.11 0.62

79 Did your

experience of

pure awareness

have an abstract

quality of “selftouch”,

but not

in a tactile sense?

-0.04 -0.07 0.06 0.00 0.11 0.04 -0.02 -0.05 -0.05 0.63 0.04 0.00 0.58

80 Was your

experience of

pure awareness

like the entire

body touching,

and

simultaneously

being touched

by, the world?

-0.05 -0.04 -0.02 0.06 0.00 -0.02 0.07 0.16 0.12 0.60 -0.04 -0.07 0.58

(Continued)

PLOS ONE “Pure awareness” in meditators: A fine-grained phenomenological analysis

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Table 6. (Continued)

Factor

1

Factor

2

Factor 3 Factor 4 Factor 5 Factor 6 Factor 7 Factor 8 Factor 9 Factor 10 Factor

11

Factor 12 Uniqueness

Item

Nr

Item long name Time,

Effort

and

Desire

Peace,

Bliss

and

Silence

Self-

Knowledge,

Autonomous

Cognizance

and Insight

Wakeful

Presence

Pure

Awareness

in Dream

and Sleep

Luminosity Thoughts

and

Feelings

Emptiness

and Nonegoic

Selfawareness

Sensory

Perception

in Body and

Space

Touching

World and

Self

Mental

Agency

Witness

Consciousness

78 Did your

experience of

pure awareness

resemble the

concrete tactile

experience you

have when you

touch your left

hand with your

right hand,

creating the

experience of

touching and

being touched at

the same location

simultaneously?

0.06 -0.13 0.04 -0.09 0.02 0.01 -0.09 -0.02 0.05 0.54 0.02 0.10 0.66

61 Did your

experience have a

quality that could

be described as

“velvety”, but in a

non-tactile sense?

0.06 0.20 -0.15 -0.11 0.09 0.17 -0.11 0.05 0.02 0.42 0.10 0.02 0.66

88 Did your

experience have a

quality of nontactile

"density"

or "fullness"?

-0.16 0.03 0.04 0.04 0.01 0.14 -0.03 -0.05 0.02 0.42 0.01 0.07 0.70

87 Did you have an

experience of

pure awareness

penetrating your

body, e.g. like a

field that also

penetrates all

other objects and

living things?

-0.10 0.05 0.06 0.04 -0.05 0.12 0.08 0.26 0.07 0.37 0.04 -0.03 0.63

58 Did you

experience the

space of pure

awareness as

having a centre?

0.17 -0.06 -0.09 0.06 0.14 0.01 0.05 -0.19 -0.06 0.28 0.06 0.01 0.74

90 Did you have a

sense of awe or

wonder?

-0.09 0.00 0.09 0.13 -0.26 0.08 0.23 -0.08 0.02 0.27 -0.08 0.14 0.70

(Continued)

PLOS ONE “Pure awareness” in meditators: A fine-grained phenomenological analysis

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Table 6. (Continued)

Factor

1

Factor

2

Factor 3 Factor 4 Factor 5 Factor 6 Factor 7 Factor 8 Factor 9 Factor 10 Factor

11

Factor 12 Uniqueness

Item

Nr

Item long name Time,

Effort

and

Desire

Peace,

Bliss

and

Silence

Self-

Knowledge,

Autonomous

Cognizance

and Insight

Wakeful

Presence

Pure

Awareness

in Dream

and Sleep

Luminosity Thoughts

and

Feelings

Emptiness

and Nonegoic

Selfawareness

Sensory

Perception

in Body and

Space

Touching

World and

Self

Mental

Agency

Witness

Consciousness

50 Did you have a

sense of

confidence that

you would be

able to know

things in the

future?

0.05 -0.09 0.12 0.02 0.15 0.14 0.19 -0.04 -0.03 0.24 0.16 -0.01 0.73

76 Was your

experience of

pure awareness

different from an

experience of

pure awareness

that “has become

aware of itself”?

-0.03 -0.07 -0.10 0.01 0.05 0.02 0.04 0.01 -0.03 0.12 -0.02 -0.03 0.97

47 Did you know

that you would

be able to

deliberately

control your

attention if you

wanted to?

-0.10 0.04 0.00 -0.04 -0.03 0.01 -0.05 0.01 0.02 -0.01 0.81 0.03 0.38

48 Did you know

that you would

be able to

deliberately think

thoughts if you

wanted to?

-0.02 0.02 0.05 -0.01 -0.01 -0.02 -0.05 0.04 0.04 -0.01 0.78 -0.01 0.41

49 Did you have a

sense of

confidence that

you would still be

alert in the next

moment?

-0.06 0.05 0.13 0.10 -0.06 0.07 -0.03 -0.11 -0.08 0.05 0.47 -0.02 0.68

37 Were you aware

of meditating?

0.07 -0.01 -0.15 0.15 0.00 -0.05 0.13 -0.07 -0.14 0.04 0.41 0.06 0.70

34 Did you have a

sense of mental

agency, in terms

of actively and

deliberately

controlling the

focus of your

attention?

0.17 -0.03 -0.24 0.08 0.00 -0.05 0.23 0.01 0.04 0.02 0.39 0.11 0.52

(Continued)

PLOS ONE “Pure awareness” in meditators: A fine-grained phenomenological analysis

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Table 6. (Continued)

Factor

1

Factor

2

Factor 3 Factor 4 Factor 5 Factor 6 Factor 7 Factor 8 Factor 9 Factor 10 Factor

11

Factor 12 Uniqueness

Item

Nr

Item long name Time,

Effort

and

Desire

Peace,

Bliss

and

Silence

Self-

Knowledge,

Autonomous

Cognizance

and Insight

Wakeful

Presence

Pure

Awareness

in Dream

and Sleep

Luminosity Thoughts

and

Feelings

Emptiness

and Nonegoic

Selfawareness

Sensory

Perception

in Body and

Space

Touching

World and

Self

Mental

Agency

Witness

Consciousness

31 Did you have the

experience of a

passive observer

being present?

-0.02 0.00 -0.01 0.05 0.02 -0.01 0.00 -0.01 0.00 -0.05 0.03 0.78 0.41

30 Did you have the

experience of an

impersonal

observer being

present?

-0.01 -0.05 0.02 0.04 -0.02 0.03 -0.02 0.05 0.02 0.00 0.01 0.75 0.43

https://doi.org/10.1371/journal.pone.0253694.t006

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“wholeness” show an absence of mental conflict and an increased degree of integration. This is

to be expected in all states in which a) the constant competition of different mental processes

for the focus of attention (for example, the automatic arising of spontaneous, task-unrelated

thought; [23–26]) has subsided, and b) representational contraction into a first-person perspective

[27] and the resulting fragmentation of one’s overall experiential space by goaldirected

mental agency have been attenuated.

A low degree of perturbation also confirms the second of six semantic constraints for the

working concept of “MPE” which were extracted in the above-mentioned study, this one

termed “Low Complexity” (PC2; cf. [9]). Generally speaking, PC2 is often described as the

complete absence of intentional content, in particular of high-level symbolic mental content

(i.e., discursive, conceptual or propositional thought), but sometimes even as the disappearance

of all sensorimotor, interoceptive and affective content. There is a weak and a strong

reading of this semantic constraint, distinguishing between the mere phenomenological

absence of cognitive agency, mind-wandering or mind blanking on the one hand (for details,

Table 7. Factor correlationsa.

Time,

Effort

and

Desire

Peace,

Bliss

and

Silence

Self-

Knowledge,

Autonomous

Cognizance

and Insight

Wakeful

Presence

Pure

Awareness

in Dream

and Sleep

Luminosity Thoughts

and

Feelings

Emptiness

and Nonegoic

Selfawareness

Sensory

Perception

in Body

and Space

Touching

World

and Self

Mental

Agency

Witness

Consciousness

Time, Effort

and Desire

1.00

Peace, Bliss

and Silence

-0.40 1.00

Self-

Knowledge,

Autonomous

Cognizance

and Insight

-0.26 0.32 1.00

Wakeful

Presence

-0.22 0.34 0.28 1.00

Pure

Awareness in

Dream and

Sleep

0.35 -0.29 -0.20 -0.29 1.00

Luminosity -0.24 0.30 0.24 0.19 -0.08 1.00

Thoughts and

Feelings

0.31 -0.06 -0.10 -0.12 0.23 0.10 1.00

Emptiness and

Non-egoic

Self-awareness

-0.30 0.21 0.22 0.07 -0.07 0.23 -0.19 1.00

Sensory

Perception in

Body and

Space

0.37 -0.19 -0.08 -0.08 0.11 0.01 0.28 -0.19 1.00

Touching

World and Self

0.06 0.24 0.15 0.12 0.15 0.31 0.18 0.13 0.09 1.00

Mental Agency 0.28 0.05 -0.03 0.11 0.00 0.01 0.20 -0.15 0.12 0.10 1.00

Witness

Consciousness

0.25 -0.13 0.03 -0.02 0.22 0.07 0.09 0.07 0.15 0.19 0.10 1.00

aCorrelations   |0.3| are printed in boldface.

https://doi.org/10.1371/journal.pone.0253694.t007

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see [9]) and a “full-absorption episode” (as defined above) on the other. Both readings are

compatible with Factor 2.

Recent research on mind-wandering has shown that “a wandering mind is an unhappy

mind” [28]. Three items in Factor 2 pick out positive mood and the phenomenal quality of

“bliss” as often co-emerging with the silent mind of the meditator. A preliminary qualitative

analysis of 841 phenomenological reports indicates that MPE as such is not an emotional state,

but that it can certainly trigger a whole spectrum of mostly positive affective states like joy,

existential relief, gratitude, unpersonal love, awe and wonder (but see [29]). In particular, MPE

can sometimes co-exist with a mostly subtle but clearly noticeable form of bliss, an experience

that has sometimes been described as an “invisible smile” (Item 65). Factor 2 therefore

expresses not only the phenomenology of peace, existential ease and silence, but also various

forms of what in German is called Stilles Entzücken (“silent delight”), which seems intimately

connected to a calm and entirely undramatic phenomenology of rapture and “non-sensational

awe.”

Factor 3 was termed “Self-Knowledge, Autonomous Cognizance and Insight”. It matches

one of the two most central semantic constraints for the concept of “MPE”, namely “Epistemicity”

(PC5 in [9]), the non-conceptual phenomenal experience of “knowingness.” This means

that MPE instantiates an autonomous (i.e., unfabricated) phenomenal character of insight,

cognizance and clarity.

The strongest-loading item in Factor 3 (“Did the experience have a quality of knowing

itself?”) expresses a phenomenology of non-egoic, first-order reflexivity: The non-conceptual

quality of “pure knowing” is self-directed, but in a non-egoic way, without the involvement of

any kind of mental or bodily agency, without a conscious sense of control or ownership, and

excluding the phenomenology of “selfhood” in terms of transtemporal identity. Accordingly,

“pure knowing” also lacks the phenomenal experience of personhood, a conscious representation

of being a rational individual possessing specific personality traits or any form of autobiographical

narrative. Phenomenologically, pure awareness simply knows itself, timelessly.

The interesting discovery is exactly that there is now empirical evidence for a non-egoic,

homunculus-free form of self-awareness. Therefore, we also find a strong phenomenological

relationship to Factor 8 ("Emptiness and Non-egoic Self-awareness"). Our own approach is

one of evidence-based phenomenology, but in ancient contemplative traditions this type of

state has for many centuries been described epistemically, as “self-knowing timeless awareness”

or as “self-cognizing wakefulness” (for example, in the Tibetan notion of rang rig ye

shes).

Factor 4 ("Wakeful Presence") integrates the phenomenology of spatiotemporal self-location

(cf. [30]) with alertness and the unified experience of “existence as such.” There is a phenomenal

experience of being fully settled in the “Here” and the “Now,” permeated by the

character of wakefulness and a feeling of “simply being.” We labelled this cluster of phenomenal

qualities “Wakeful Presence” because its four strongest-loading items refer to the embodied

experience of wakefully being in the present moment. The alertness component directly relates

to and confirms the first, and most prominent, semantic constraint for the concept of “MPE,”

as derived from a previous study, namely “Wakefulness” (PC1 in [9]). If one interprets wakefulness

as a functionally autonomous conscious representation of epistemic capacity (for

example, of the existing capacity for self-orientation in time and space, plus the capacity for

attentional control), then one finds a direct link to Factor 3 ("Self-Knowledge, Autonomous

Cognizance and Insight"). In Tibetan Buddhism, the relevant phenomenology was described

more than a thousand years ago as “self-generating ever-fresh awareness” ([31], xi) and as the

experiential quality of originary, naturally present and non-transient “primordial knowing”

(ye shes in Tibetan; cf. [32], p447, [33], p99).

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Factor 4 also incorporates two additional elements, however, namely items pointing to the

phenomenal qualities of unity and of onticity (pure being, or being as such). The latter has also

been reported in the context of syncopes and accidents (for discussion, see [9], note 21). Both

reappear in our qualitative assessment under the rubric of “non-dual being.”

Factor 5 (“Pure Awareness in Dream and Sleep”) is a special case and will, if replicated, be

treated more thoroughly in future publications. It relates to the experience of pure awareness

during NREM (non-rapid eye movement) sleep, which is a type of full absorption [34, 35]. As

the second “stand-alone instance” of our research target, it will be of great relevance in triangulating

the neural correlates of MPE. A number of first-person reports from our study support

the existence of such states.

Pure awareness during NREM-sleep has previously been termed “lucid dreamless sleep” or

(by the TM movement) “witnessing sleep.” Factor 5 shows interesting relations not only to the

phenomenologies of “wakeful presence” and “non-dual being” already mentioned, but also to

Factor 12 (“Witness Consciousness”) and Factor 6 (“Luminosity”).

Factor 6 (“Luminosity”) refers to non-visual phenomenal qualities of “brightness,” “radiance”

and “vibrancy,” but also to the visual experience of brightness with closed eyes. In addition,

“Self-Luminosity” (PC3) was one of the six semantic constraints previously extracted,

where it may also be found as the phenomenology of “brilliance” or as the “clear light of primordial

awareness.”

The specific kind of phenomenal character sometimes described as “luminosity,” “radiance”

or even “enlightenment” comes in different varieties. For example, many practitioners

describe a non-visual phenomenology of “clear light,” a non-perceptual experience of clarity

and mere epistemic openness, while others report a more concrete form of visual brightness,

which can be experienced with closed as well as with open eyes.

According to classical Buddhist teachings, the term “luminosity” simply refers to an entirely

non-conceptual experience of epistemic capacity, the capacity to know and experience (Tib.

salwa; e.g., [36], p36; n. 30), and would therefore be directly related to Factor 3 (“Self-Knowledge,

Autonomous Cognizance and Insight”). Here, we could also speak of the phenomenal

experience of epistemic clarity. This involves an open, currently unobstructed inner space of

knowing, a space in which orientation and perceptual processes can unfold, in which attention

can be controlled and focused or in which concepts can be formed and applied to experience.

MPE would be a model of this space.

Factor 7 (“Thoughts and Feelings”) describes a classical meditation experience, just like the

phenomenal descriptors picked out by “Time, Effort and Desire” (Factor 1). Thoughts of different

kinds, mental images, emotions, memories and simulations of future events spontaneously

arise. There is time experience, and the space of silent, spacious awareness into which

the meditator wants to settle is more or less clouded. Phenomenologically, there is a mostly

noisy foreground of active mental content.

Factor 8 (“Emptiness and Non-egoic Self-awareness”) may be most interesting from a

philosophical perspective. In our study, it refers to an experiential quality of “pure knowing”

without a sense of self and without any object. The relevant items describe an uncontracted,

unbounded, and non-dual experience of wakefulness without content, which is self-aware,

knowing only itself in a way that lacks any markers of egoic self-consciousness like agency,

ownership, and autobiographical narrative, or spatiotemporal self-location [27, 30]. However,

our formulation of the strongest-loading item in “Emptiness and Non-egoic Self-awareness”

may mistakenly conflate “emptiness” with the merely spatial phenomenology of consciously

experiencing a void or a vacuum.

“Emptiness” (su  atā in Pali) is one of the foremost concepts in Buddhist philosophy. It

has been discussed by scholars and practitioners for far more than two thousand years. From a

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metaphysical perspective, “emptiness” means that all phenomena lack substantiality and an

intrinsic nature of their own. From a phenomenological perspective, full-absorption states in

which pure awareness remains as the only reportable phenomenal character are a prime candidate

for an “experience” of emptiness, the stand-alone quality of epistemic openness as discussed

in the context of Factor 6 above. Phenomenologically, “seeing the empty nature of

phenomena” can also refer to a conscious experience without the slightest trace of conceptual

overlay, namely to the distinct and crystal-clear phenomenology of seeing and perceiving out

of timeless silence.

Interestingly, the second- and third-strongest loading items in Factor 8 were those offering

two metaphorical descriptions of first-order reflexivity combining the “Self-Knowledge,

Autonomous Cognizance and Insight” of Factor 3 and the “Wakefulness” of Factor 4 with the

phenomenal quality of emptiness and epistemic openness. These are negatively correlated with

the phenomenology of selfhood: The phenomenology of self-knowing and self-awakening

picked out by this factor is non-egoic. Arguably, it is exactly these aspects of Factor 8 that, for

many participants, may express the “spiritual essence” of MPE most directly. Evidence for the

actual existence of non-egoic self-awareness in the context of a substantial psychometric study

is a theoretically relevant result.

Factor 9 (“Sensory Perception in Body and Space”) describes the presence of sensory qualities,

movement sensations and conscious body experience, implying that the phenomenal

character of MPE can co-emerge with perceptual content. Qualitative analysis of reports

shows it as related to the frequently described phenomenology of “direct perception.” For

many centuries, meditators have reported states of direct perception, the experience of seeing

what is. Seeing what is out of a state of pure awareness often reveals another particular and

interesting, phenomenal quality, namely the experience of “suchness” or “thusness”, the ineffable

uniqueness and particularity of any individual instance of non-conceptual content. This

suggests another evidence-based, phenomenologically grounded reading of the “purity” of

pure awareness, not as the absence of perceptual content, but as a complete lack of conceptual

overlay and cognitive penetration, including time experience and judgements as to the “existence”

or “non-existence” of what is perceived.

Factor 10 (“Touching World and Self”) describes MPE as an abstract form of tactile experience

resembling self-touch (for example, the specific sensation of inter-manual self-touch) or

as a tactile experience in which the entire body touching the world while simultaneously being

touched by it. Other phenomenological descriptors are “velvety,” “dense” and “full”—but

always in a non-tactile way, i.e., as lacking the concrete phenomenal qualities normally characterizing

the stimulus-correlated sense of touch. Here, the phenomenological profile of MPE is

described, first, as an abstract form of contact or of “being in touch;” second, it can exhibit the

phenomenal character of reflexivity (as in self-touch; or Factor 8; [37, 38]); and, third, it can

be globalized, namely in the form of “an experience of pure awareness penetrating your body,

e.g. like a field that also penetrates all other objects and living things” (Item 87). One interesting

detail is the correlation of Factor 10 with Factor 6 (“Luminosity”). As there is no obvious

phenomenological relationship between qualities like “brightness,” “brilliance” or “radiance”

and the ones just mentioned, this might perhaps point to interesting commonalities in the

neural substrate.

Factor 11 ("Mental Agency") points to subtle forms of egoic mental self-awareness, like

being aware of the fact that one is currently meditating, experiencing the potential for sustained

alertness and cognitive-attentional self-control, or even—in Item 34—having an explicit

sense of mental agency unaccompanied by any actually ongoing, deliberate control of the

focus of attention. This factor picks out phenomenological configurations in which egoic

awareness, specifically the more subtle phenomenal qualities emerging from representing

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one’s own capacity for mental action, are still superimposed onto MPE. This feature also refers

back to the notion of “dual mindfulness” as introduced when discussing Factor 1 ("Time,

Effort and Desire").

Finally, Factor 12 ("Witness Consciousness") demonstrates how a classical term from the

Advaita Vedanta (i.e., sākṣin; Sanskrit: साक्षी; [39, 40]) system of philosophy finds its expression

on the level of phenomenology. Witness consciousness is that which makes all knowledge

possible, cannot itself become an object of knowledge and is self-luminous (for more, see [9]).

“Witness consciousness” also is a global phenomenology. This is to say that the totality of all

experiential contents is experienced as being observed by something that isn’t really an

“observer” at all, but rather a timeless, absolutely impersonal, knowing presence. Phenomenologically,

the world is mirrored in an all-encompassing quality of infinite, choiceless and nonconceptual

knowing.

It is interesting to note how Factors 3 (“Self-Knowledge, Autonomous Cognizance and

Insight”) and 4 (“Wakeful Presence”) offer phenomenological support for results from the textbased

evidence synthesis presented in [9], in which the two most important semantic constraints

for MPE emerge as and “Epistemicity” (PC3) and “Wakefulness” (PC1), while Factor

6 (Luminosity”) directly maps onto the constraint which was termed “self-luminosity” (PC3)

in this earlier investigation. Meanwhile, a highly intuitive pattern found in the present data is

that the qualities of control, desire, effort and time experience found under Factor 1 are clearly

anti-correlated with “Peace, Bliss, and Silence (Factor 2) and what is arguably the most “spiritual”

factor (Factor 8, “Emptiness and Non-egoic Self-awareness”), while positively correlating

with dream, sleep, and mental activity on the cognitive and perceptual level.

Insofar as it is phenomenologically plausible, the 12-factor solution presented shows that a

dimensional approach is viable and that the concept of “MPE” may be a graded construct

which refers to a multidimensional space of possible conscious states, a space which may contain

different points, regions or trajectories [9, 41]. MPE might then be a cluster concept with

a probabilistic rather than a definitional structure, where membership is graded along multiple

dimensions and some phenomenological exemplars are more prototypical than others. Since

“pure awareness” experiences may be maximally prototypical, we might conjecture that a

majority of respondents in our study will describe such states as the simplest kind of conscious

experience they know. This is borne out by the fact that the corresponding item #86 in our

questionnaire achieved a median rating of 80. However, it is important not to conflate subjective

ratings of “simplicity” with whatever objective measures we may develop in the future.

Accordingly, future research may demonstrate that even less complex forms of phenomenal

character do exist and constitute the simplest form of conscious experience neurotypical

human beings are capable of.

Limitations

Our study has a number of limitations. Most fundamentally, there is no guarantee that participants

understood the instructions and the concept of “pure awareness” introduced therein in

the way we intended them. Varying understandings may have led to unwanted variation in

responses. Even assuming a singular, precise and unequivocal understanding, it is still possible

that some responses were driven largely by a desire to report particularly impressive or personally

meaningful experiences rather than to adhere as closely as possible to the instructions.

There is some evidence for this in the 841 phenomenal reports collected as part of the questionnaire,

where a number of participants chose to report not “ordinary” MPE as it may occur

during formal meditation practice and full-absorption episodes, but rarer and often quite dramatic

non-dual awareness states in which all subject–object structure had spontaneously

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disappeared. This may have been an indirect effect of us asking participants for a description

of an experience “in which the quality of pure awareness was particularly salient and/or one

which you can remember particularly clearly.” What can be remembered particularly clearly

may often be the most impressive states, which may not necessarily be the most paradigmatic

instances of “pure awareness.”

More generally, differences in understanding of any part of the survey (items, demographic

questions) could have led to undesired response variability. Such differences can occur for a

number of reasons. First, participants will typically have been exposed to different background

information about meditation. If they have actively engaged with the relevant literature, there

may have been large differences in what was selected for study. For instance, many of our participants

(77%) were regular practitioners who had been meditating for years. It is plausible to

assume that such a consistent habit may often be anchored in adherence to specific belief systems

and the conceptual framework of a certain lineage or spiritual tradition or a specific

teacher or organization. The terminology employed by such theories, as well their epistemological

and metaphysical background assumptions, may “contaminate” survey responses (and

phenomenological reports). We know from correspondence that such belief systems can

sometimes even lead to a decision not to participate in scientific projects or to reject any

attempt to try to approximate something considered to be as fundamentally ineffable and

soteriologically relevant as MPE. Therefore, “theory contamination” may have both biased

questionnaire responses and introduced a selection bias into the sample.

A second issue is what could be called “response drift”: Some participants may have started

out with a somewhat vague idea of the target state of pure awareness, which became increasingly

focused as they moved through the questionnaire. Conversely, they may have started out

with a very specific concept, perhaps dictated by commitment to a particular theory, and then

similarly shifted as they moved through the questions. Responses given earlier may therefore

have related to a somewhat different target than what later responses referred to. This could

explain the observed divergence in responses to the two control items, which occurred at different

places in the questionnaire, but were nearly identically phrased. In hindsight, it might

have been better to phrase these items not just nearly, but absolutely, identically in order to be

sure that any intra-individual variation in responses must be due to inconsistent reporting. As

it was, divergent scores could also be due to the slight semantic difference in the two items,

one asking about non-visual radiance only, while the other also asked about self-luminosity.

We did not exclude any participants based on the difference in their control item scores. We

are generally very cautious about excluding participants and prefer to err on the side of inclusion

unless there is a compelling rationale for doing otherwise. Also, a non-arbitrary exclusion

criterion is hard to find in this case. But most importantly, a single pair of control items is

much too noisy a criterion to offer a sound basis for data exclusion.

In studies of “private” subjective experiences, there is a general set of problems associated

with verbal report. One issue is ineffability: the difficulty or impossibility of expressing certain

phenomenal states or qualities in words. This problem may be particularly pronounced when

it comes to MPE, since the experiential quality of “pure awareness” has long been regarded by

meditators as the paradigmatic example of ineffability. The ineffability problem may arise for

several reasons. One is a lack of concurrent reportability during full-absorption episodes ([9],

p14). Due to the non-dual nature of such states (i.e., the lack of any phenomenally represented

subject–object structure) there will be no intention or cognitive capacity to verbally report,

mentally categorize or actively memorize the phenomenal character in question. Another reason

may be that MPE’s timeless content is unlike [42, 43] any of the more familiar sensory,

motor and interoceptive qualities, making it hard to grasp it verbally by comparing it to such

qualities. A final source of ineffability is that the experience of MPE typically seems to lack any

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internal structure or “grain,” It seems uniformly dense. This phenomenal quality of “ultrasmoothness”

[44–46], as it is called in the literature, may further hinder verbal report by

depriving it of any discernible entry points for description or functional analysis.

Alongside ineffability issues, another problem faced by all studies based on retrospective

self-report is the unreliability of memory recall. Human autobiographical memory, including

recall of previous mental states, is notoriously fallible (for a review see [47]). In our study, we

asked participants to report on experiences that occurred in their past, possibly even decades

ago. Memory retrieval for such events will be necessarily biased, depending on various factors

such as the amount of time that has since passed. The uncertainty introduced by such errors

may be substantial but is likely to remain unavoidable in studies of this kind.

On a conceptual level there is an even deeper variant of the memory problem: If the concept

of “autobiographical memory” refers to the representation of events which at the time at which

they occurred were phenomenally represented as being experienced by a conscious self, then a

participant’s claims that they themselves have experienced a selfless state are highly dubious

from a methodological perspective, because they contain either a logical or a performative fallacy

([48], p566). A memory of a pure-awareness experience could not be autobiographical

memory in this strong phenomenological sense. Of course, it may be empirically possible that

selfless states are stored and later retrieved in an autobiographical format, as a post hoc mnemonic

misrepresentation adding the feature of egoic self-awareness–a case of misremembering,

and not of confabulation (cf. [49, 50] for important discussions). But the relevant evidence

has yet to be gathered.

One weakness of our anonymized online survey approach is that the identities of participants

could not be verified, nor could we detect fraudulent responses or multiple responses by

the same person. As part of privacy protection, IP addresses were not stored and could therefore

not be used for data plausibility checks.

Finally, our data are highly unlikely to be representative of the global population of meditators.

The online nature of the questionnaire and its distribution channels as well as self-selection

will have produced a sample that deviates in several respects from the global population.

The high number of incomplete responses (over 60%) also indicates a massive self-selection

process, probably driven in part by the large number of questionnaire items, which may have

been off-putting. However, representativeness is not a major concern at this stage. Future versions

of this questionnaire will be put to the test against different populations and will be modified

to provide a factor structure that holds up in as many settings as possible. Methods from

confirmatory factor analysis can then be used to quantify the differences in item functioning

and response patterns among different groups of participants.

Conclusion

A central notion in traditional philosophical theories of meditation is that of “pure consciousness”

or “pure awareness,” the experience of being non-conceptually aware of consciousness

itself. Based on responses to an online questionnaire, we here offer a factor structure to map

the phenomenal character of such experiences in a fine-grained way. The 12 resulting dimensions

not only reproduce important aspects of this phenomenon as reported in the literature,

such as the actual existence of non-egoic self-awareness, they also point to some potentially

new connections such as that between “Luminosity” and the abstract, non-tactile experience of

self-touch.

However, our factor solution accounts for less than half of the item variance and quantitative

measures indicate a lack of fit, particularly when simple structure is imposed. Future studies

will be needed to improve upon this first version of the rating scale and to continue to

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validate it in different populations and settings, including sleep states, non-meditative states

and altered states of consciousness.

The under-researched experience of “pure awareness” in meditation is of great relevance to

the interdisciplinary field of consciousness research. Pure awareness opens up a new methodological

perspective by generating potential for a minimal model explanation, which in turn will

contribute to the construction of a minimal unifying model (cf. [9, 51]). The study of pure

awareness also helps in refining important theoretical questions in consciousness studies, for

instance as regards ineffability and the relevance of dimensional approaches to fine-grained

phenomenological analysis. Finally, it may foster theoretical unification by connecting the

major existing approaches in a new way.

Acknowledgments

We thank Tiziano Furlanetto, Sol ne Neyret, Adriana Alcaraz Sanchez, Jennifer Windt and

Raphae l Milli re for help with questionnaire translation. We are grateful to Tiziano Furlanetto,

Sol ne Neyret, Adriana Alcaraz Sanchez and Wanja Wiese for help with translation and qualitative

assessment of phenomenological reports. In particular, TM wants to thank all those

committed practitioners who supported the project during the pilot and distribution phase,

including Nicole Baden, Tilman Borghardt, Irene Bumbacher, Cyril Costines, Safae Essafi,

Nicole Fasel, Catherine Felder, Matt Gwyther, Sam Harris, Britta Ho lzel, Gu nter Hudasch,

Yuka Nakamura, Muho No lke, Ulrich Ott, Fred von Allmen, Toby Woods and others. We are

greatly indebted to Erich Studerus for comments, and to Emily Troscianko, Wanja Wiese, and

Cyril Costines for editorial help.

Author Contributions

Conceptualization: Alex Gamma, Thomas Metzinger.

Data curation: Alex Gamma.

Formal analysis: Alex Gamma.

Funding acquisition: Thomas Metzinger.

Methodology: Alex Gamma, Thomas Metzinger.

Resources: Thomas Metzinger.

Supervision: Thomas Metzinger.

Visualization: Alex Gamma.

Writing – original draft: Alex Gamma, Thomas Metzinger.

Writing – review & editing: Alex Gamma, Thomas Metzinger.

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