ArticlePDF Available

Abstract and Figures

The 30-item revised Mystical Experience Questionnaire (MEQ30) was previously developed within an online survey of mystical-type experiences occasioned by psilocybin-containing mushrooms. The rated experiences occurred on average eight years before completion of the questionnaire. The current paper validates the MEQ30 using data from experimental studies with controlled doses of psilocybin. Data were pooled and analyzed from five laboratory experiments in which participants (n=184) received a moderate to high oral dose of psilocybin (at least 20 mg/70 kg). Results of confirmatory factor analysis demonstrate the reliability and internal validity of the MEQ30. Structural equation models demonstrate the external and convergent validity of the MEQ30 by showing that latent variable scores on the MEQ30 positively predict persisting change in attitudes, behavior, and well-being attributed to experiences with psilocybin while controlling for the contribution of the participant-rated intensity of drug effects. These findings support the use of the MEQ30 as an efficient measure of individual mystical experiences. A method to score a "complete mystical experience" that was used in previous versions of the mystical experience questionnaire is validated in the MEQ30, and a stand-alone version of the MEQ30 is provided for use in future research.
Content may be subject to copyright.
Journal of Psychopharmacology
1 –9
© The Author(s) 2015
Reprints and permissions:
sagepub.co.uk/journalsPermissions.nav
DOI: 10.1177/0269881115609019
jop.sagepub.com
Introduction
Reports of mystical-type experiences have been provided by reli-
gious and non-religious figures around the world and throughout
recorded history (James, 1902; Stace, 1960). Common dimen-
sions in reports of mystical experiences include the experience of
profound unity with all that exists, a felt sense of sacredness, a
sense of the experience of truth and reality at a fundamental level
(noetic quality), deeply felt positive mood, transcendence of time
and space, and difficulty explaining the experience in words
(ineffability; Stace, 1960). This operational definition was pro-
vided by Stace (1960), and formed the basis of different versions
of the Mystical Experience Questionnaire (MEQ), which was
developed to evaluate the occurrence and character of individual,
discrete mystical experiences occasioned by classic hallucino-
gens (Griffiths et al., 2006; MacLean et al., 2012; Pahnke, 1963).
The MEQ has been administered in various forms in a number
of studies over the past 50 or more years (Bogenschutz et al.,
2015; Garcia-Romeu et al., 2015; Griffiths et al., 2006, 2008,
2011; Johnson et al., 2014; MacLean et al., 2012; Pahnke, 1963,
1967; Richards, 1975). The most frequently used version of
the MEQ is the 43-item Mystical Experience Questionnaire
(MEQ43), also called the Pahnke–Richards Mystical Experience
Questionnaire. The MEQ43 contains 43 items that were theoreti-
cally derived and qualitatively organized into seven subscales
(internal unity, external unity, sacredness, noetic quality, positive
mood, transcendence of time and space, and ineffability). The
MEQ43 has been used in prospective studies of the subjective
effects (Griffiths et al., 2006, 2008, 2011) and therapeutic out-
comes (Bogenschutz et al., 2015; Garcia-Romeu et al., 2015;
Johnson et al., 2014) of ingestion of psilocybin. MEQ43 scores
are shown to be dose dependent (Griffiths et al., 2011) and pre-
dict therapeutic outcomes of psilocybin sessions (Bogenschutz
et al., 2015; Garcia-Romeu et al., 2015). However, the factor
structure of the MEQ43 has only recently undergone psychomet-
ric investigation (MacLean et al., 2012).
The most recently developed version of the MEQ (the 30-item
revised Mystical Experience Questionnaire, or MEQ30) was
developed and validated through factor analysis of retrospective
accounts of profound experiences with psilocybin-containing
mushrooms (MacLean et al., 2012). That analysis yielded a four-
factor structure of the MEQ30, containing 30 items from the pre-
vious MEQ43, which was typically administered within the
100-item States of Consciousness Questionnaire (Griffiths et al.,
2006, 2011). The four factors of the MEQ30 are: mystical
(including items from the internal unity, external unity, noetic
quality, and sacredness scales of the MEQ43), positive mood,
transcendence of time and space, and ineffability (all three of
which include items from their respective MEQ43 scales). Thus,
the MEQ30 retains items from each qualitative subscale in the
original MEQ43, but in a reduced number of dimensions. The
Validation of the revised Mystical Experience
Questionnaire in experimental sessions with
psilocybin
Frederick S Barrett1, Matthew W Johnson1 and Roland R Griffiths1,2
Abstract
The 30-item revised Mystical Experience Questionnaire (MEQ30) was previously developed within an online survey of mystical-type experiences
occasioned by psilocybin-containing mushrooms. The rated experiences occurred on average eight years before completion of the questionnaire. The
current paper validates the MEQ30 using data from experimental studies with controlled doses of psilocybin. Data were pooled and analyzed from
five laboratory experiments in which participants (n=184) received a moderate to high oral dose of psilocybin (at least 20 mg/70 kg). Results of
confirmatory factor analysis demonstrate the reliability and internal validity of the MEQ30. Structural equation models demonstrate the external and
convergent validity of the MEQ30 by showing that latent variable scores on the MEQ30 positively predict persisting change in attitudes, behavior, and
well-being attributed to experiences with psilocybin while controlling for the contribution of the participant-rated intensity of drug effects. These
findings support the use of the MEQ30 as an efficient measure of individual mystical experiences. A method to score a “complete mystical experience”
that was used in previous versions of the mystical experience questionnaire is validated in the MEQ30, and a stand-alone version of the MEQ30 is
provided for use in future research.
Keywords
Psilocybin, hallucinogens, entheogen, psychedelic, spiritual, mystical experience, factor analysis, structural equation modeling, psychometrics
1
Department of Psychiatry and Behavioral Sciences, Johns Hopkins
University School of Medicine, Baltimore, MD, USA
2 Department of Neuroscience, Johns Hopkins University School of
Medicine, Baltimore, MD, USA
Corresponding author:
Frederick S. Barrett, Department of Psychiatry and Behavioral Sciences,
Johns Hopkins University School of Medicine, 5510 Nathan Shock
Drive, Baltimore, MD 21224, USA.
Email: fbarret2@jhu.edu
609019JOP0010.1177/0269881115609019Journal of PsychopharmacologyBarrett et al. MEQ validation
research-article2015
Original Paper
at JOHNS HOPKINS UNIVERSITY on October 8, 2015jop.sagepub.comDownloaded from
2 Journal of Psychopharmacology
MEQ30 is not an alternate form of the MEQ43, but rather a psy-
chometrically validated instrument that is derived from the
MEQ43.
Factor structures underlying questionnaires assessing mysti-
cal experiences have received a fair amount of attention in the
psychology of religion (Chen et al., 2011a, 2011b, 2012; Hood
et al., 2001). In particular, the Hood Mysticism Scale (HMS;
Hood 1975, 2009) is a well-validated instrument that was derived
from the same theoretical basis as the MEQ, and it consists of
similar underlying content domains. However, the HMS and the
MEQ differ in specific items, underlying factor structure, and the
time frame over which dimensions of mystical experiences are
assessed. The HMS has been applied as a measure of phenomena
occurring over a lifetime, whereas the MEQ assesses phenomena
occurring during a single, discrete experience. Furthermore, the
items of the HMS consistently organize into a three-factor struc-
ture (Chen et al., 2011a, 2011b, 2012; Hood et al., 2001).
The items of the MEQ30 fit well in the four-factor structure
described above, and this four-factor structure of the MEQ30
yielded superior model fit when compared with two alternative
three-factor structures that were derived from the HMS (MacLean
et al., 2012).
The MEQ30 was developed and validated using online sur-
veys of retrospective accounts of mystical and spiritual experi-
ences encountered after ingesting psilocybin-containing
mushrooms (MacLean et al., 2012). The conditions under which
these experiences occurred were uncontrolled, and reports were
based on retrospective accounts of experiences that occurred on
average eight years before the given ratings. While psychometric
properties of the MEQ30 were found to be stable and reliable
across different online survey samples assessing the effects of
psilocybin-containing mushrooms, the factor structure of the
MEQ30 has not yet been replicated in data from studies of con-
trolled-dose psilocybin administration in a laboratory setting.
Also, while earlier versions of the MEQ43 included a method to
identify a “complete mystical experience,” which was increased
by psilocybin (Griffiths et al., 2006, 2011; Pahnke, 1967), an
analogous method for scoring a complete mystical experience
has not been demonstrated in the MEQ30. This “complete mystical
experience” may serve as a valuable predictor of positive out-
comes. Cancer patients who met the criteria for a “complete mys-
tical experience” in a study of psychedelic-assisted psychotherapy
showed greater clinical improvements than did those who did not
meet these criteria (Richards et al., 1977). Healthy adults who
met the criteria for a “complete mystical experience” showed
increases in openness after psilocybin administration, while
those who did not meet the criteria did not show these changes
(MacLean et al., 2011).
The aim of the current study is to replicate and demonstrate
the reliability of the factor structure of the MEQ30 in data col-
lected in a controlled laboratory setting. In this study, the MEQ30
is validated with data from five experimental psilocybin studies
in which participants received a moderate to high dose of psilo-
cybin (20 mg/70 kg; Griffiths et al., 2006, 2011; Johnson et al.,
2014; cancer-related anxiety/depression study, in preparation;
spiritual practice study, in preparation). Confirmatory factor
analysis of MEQ30 items demonstrates the internal validity of
the MEQ30. The external validity of the MEQ30 is demonstrated
using structural equation modeling, regressing ratings of persist-
ing effects of psilocybin on both latent variable scores from the
MEQ30, and participant ratings of the overall strength of drug
effects. The specificity of the MEQ30 is established by showing
that latent scores, but not participant ratings of overall drug
strength, are related to persisting effects attributed to psilocybin.
Finally, the MEQ43 method for dichotomously scoring the pres-
ence of a complete mystical experience is adapted to the MEQ30.
Methods
Participants
Data were pooled across five laboratory experiments in which
participants received a moderate to high oral dose of psilocybin
ranging between 20 and 30 mg/70 kg. One observation was
included per participant. For each observation, the maximum
dose received for that participant was included in the analysis
because the probability of fulfilling criteria for having a complete
mystical experience on the MEQ43 is an increasing function of
psilocybin dose (Griffiths et al., 2011). Each study was conducted
in compliance with US laws and approved by the Johns Hopkins
University School of Medicine Institutional Review Board. All
participants provided informed consent.
Study 1: Griffiths et al. (2006). Thirty-six participants com-
pleted a double-blind human pharmacology study comparing the
subjective effects of psilocybin and methylphenidate. Thirty par-
ticipants received either psilocybin (30 mg/70 kg) or methylphe-
nidate (40 mg/70 kg) in counterbalanced order across two
experimental sessions. Six participants did not complete all study
questionnaires, and were excluded from the analyses. A further
six participants completed all questionnaire material and received
psilocybin (30 mg/70 kg) after having received methylphenidate
on two previous sessions. Included in the analyses were data
from the psilocybin session for the 30 participants who com-
pleted all the relevant questionnaires.
Study 2: Griffiths etal. (2011). Eighteen participants in this
double-blind study received either an ascending or descending
sequence of five psilocybin doses (0, 5, 10, 20, and 30 mg/70 kg),
each in a separate experimental session, with the placebo inserted
in the sequence in pseudo-random order. Data from each partici-
pant’s high-dose session (30 mg/70 kg) were included in the
analysis.
Study 3: Johnson etal. (2014). Fifteen participants completed
an open label pilot study investigating the utility of two or three
psilocybin sessions (20 or 30 mg/70 kg) as an aid to smoking ces-
sation. Data from each participant’s highest-dose session were
included (30 mg/70 kg, n=14; 20 mg/70 kg, n=1). If the partici-
pant received the highest dose twice, the first exposure was used
as that participant’s observation.
Study 4: Spiritual practices study (in preparation). Sev-
enty-five participants completed a double-blind study of the
interaction between psilocybin and training in meditation and
other spiritual practices. Fifty participants received 20 and 30
mg/70 kg psilocybin on the first and second experimental ses-
sions, respectively. The remaining participants (n=25) received a
very low dose of psilocybin (1 mg/70 kg) on two experimental
at JOHNS HOPKINS UNIVERSITY on October 8, 2015jop.sagepub.comDownloaded from
Barrett et al. 3
sessions, and 21 of these participants opted to receive a high dose
of psilocybin (30 mg/70 kg) on a third experimental session. Data
from all 30 mg/70 kg sessions (n=71) were included in the
analysis.
Study 5: Cancer-related anxiety/depression study (in
preparation). Fifty-one participants were enrolled in a dou-
ble-blind study investigating the effects of psilocybin in people
with anxiety and/or depressed mood comorbid with a life-
threatening cancer diagnosis. Participants received either a
very low dose (1 or 3 mg/70 kg) or a moderately high dose (22
mg/70 kg) of psilocybin over two counterbalanced experimen-
tal sessions. One participant received a high dose of psilocybin
(30 mg/70 kg). Data from the 50 participants who received the
moderately high dose session were included in the analysis.
Measures
The MEQ43. At the end of each experimental session of each
study, participants completed a battery of questionnaires that
included the States of Consciousness Questionnaire (SOCQ).
The SOCQ is a 100-item questionnaire that contains the 43
items of the original MEQ43 (Griffiths et al., 2006). Each item
of the MEQ43 was rated on a 6-point scale, where 0=“none; not
at all,” 1=“so slight cannot decide,” 2=“slight,” 3=“moderate,”
4=“strong (equivalent in degree to any previous strong experi-
ence or expectation of this description),” and 5=“extreme (more
than ever before in my life and stronger than 4).” The MEQ43
is comprised of seven subscales: internal unity, external unity,
sacredness, noetic quality, deeply felt positive mood, transcen-
dence of time and space, and ineffability/paradoxicality. Scale
scores for each participant are generated from the sum of
responses to all items of a given scale.
The MEQ30. The MEQ30 is constructed from a subset of 30
items from the MEQ43 (MacLean et al., 2012), and is comprised
of four factors: mystical (including items from the internal unity,
external unity, noetic quality, and sacredness scales of the
MEQ43), positive mood, transcendence of time and space, and
ineffability (all three of which include a subset of items from the
parallel scales within the MEQ43). Responses to the items com-
prising the MEQ30 in the analysis were taken from participant
responses to the MEQ43, which was embedded within the 100-
item SOCQ. Responses to the items of the MEQ30 were submit-
ted to confirmatory factor analysis and structural equation
modeling for the purposes of validating the MEQ30 within labo-
ratory experimental data.
The Persisting Effects Questionnaire. At a period of approxi-
mately three to eight weeks (which varied across studies) after
each experimental session, participants in each study completed a
questionnaire assessing persisting behavioral and psychological
changes that they attributed to their most recent experimental ses-
sion. In this questionnaire, participants indicated the meaningful-
ness of their experience (“How personally meaningful was the
experience?”) using an 8-point ordinal scale (1=“no more than
routine, everyday experiences,” 2=“similar to meaningful experi-
ences that occur on average once a week,” 3=“similar to meaning-
ful experiences that occur on average once a month,” 4=“similar
to meaningful experiences that occur on average once a year,”
5=“similar to meaningful experiences that occur on average once
every 5 years,” 6=“among the top 10 most meaningful experi-
ences of my life,” 7=“among the top 5 most meaningful experi-
ences of my life,” and 8=“the single most meaningful experience
of my life”). Participants also indicated the degree to which their
experience was spiritually significant (“Indicate the degree to
which the experience was spiritually significant to you:”) using a
6-point rating scale (1=“not at all,” 2=“slightly,” 3=“moderately,”
4= “very much,” 5=“among the top 5 most spiritually significant
experiences of my life,” and 6=“the single most spiritually signifi-
cant experience of my life”). Participants responded to a question
inquiring about the effect of the experience on their well-being or
life satisfaction (“Do you believe that the experience and your
contemplation of that experience have led to a change in your cur-
rent sense of personal well-being or life satisfaction?”) using a
7-point rating scale (+3, “increased very much”; +2, “increased
moderately”; +1, “increased slightly”; 0, “no change”; –1,
“decreased slightly”; −2, “decreased moderately”; and −3,
“decreased very much”). Finally, participants indicated the degree
to which their experience had a positive impact on their behavior
following the session (“Your behavior has changed in ways you
consider positive since the experience.”), using a 6-point rating
scale (0=“none, not at all”; 1=“so slight, cannot decide”;
2=“slight”; 3=“moderate”; 4=“strong”; 5=“extreme”).
The Hallucinogen Rating Scale. The Hallucinogen Rating
Scale (HRS; Strassman et al., 1994) is a 100-item question-
naire designed to assess subjective effects of hallucinogenic
substances. The HRS includes a 4-item intensity scale. Three
items from the intensity scale (intensity, a rush, and high) were
rated on a 5-point rating scale (1=“not at all,” 2=“slightly,”
3=“moderately,” 4=“very much,” 5=“extremely”) and the
fourth item (amount of time between when the drug was
administered and feeling an effect) was rated on a 6-point rat-
ing scale (1=“not applicable, no effect”; 2=“0–15 minutes”;
3=“15–30 minutes”; 4=“30–60 minutes”; 5=“60–90 minutes”;
and 6=“>90 minutes”). Intensity scale scores from the HRS
were added to structural equation models of the effects of the
MEQ30 on persisting effects attributed to psilocybin. Separate
structural equation models were estimated using just the single
rating of the intensity item from the HRS (item 99), as this item
does not confound subjective strength of drug effects with any
other dimensions (such as rush, high, and speed of onset).
These variables were included in the structural equation models
to rule out the plausible alternative hypothesis that persisting
effects attributed to psilocybin are due to the strength of the
overall drug effect rather than any attribution or dimension
related to mystical experience.
Analysis
Internal and external validity of the MEQ30. MEQ30 items
were entered into a series of confirmatory factor analyses to vali-
date the factor structure and internal validity of the MEQ30
against previously proposed and demonstrated alternate models
(MacLean et al., 2012). Data were fit to three competing models:
the four-factor structure of the MEQ30, a three-factor “Hood”
model, and a three-factor “Stace” model.
at JOHNS HOPKINS UNIVERSITY on October 8, 2015jop.sagepub.comDownloaded from
4 Journal of Psychopharmacology
The four-factor structure of the MEQ30 was the product of
exploratory and confirmatory factor analyses of the initial item pool
of the MEQ43 (MacLean et al., 2012). In this four-factor structure,
items 9, 12, 14, 22, 35, 36, 41, 47, 54, 55, 69, 73, 74, 77, and 83
from the MEQ43 (a subset of items from the internal unity, external
unity, sacredness, and noetic quality factors of the MEQ43) loaded
onto factor 1, mystical; items 5, 18, 30, 43, 80, and 87 (a subset of
items from the positive mood factor of the MEQ43) loaded onto
factor 2, positive mood; items 2, 15, 29, 34, 48, and 65 (a subset of
items from the transcendence of time and space factor of the
MEQ43) loaded onto factor 3, transcendence of time and space; and
items 6, 23, and 86 (a subset of items from the ineffability factor of
the MEQ43) loaded onto factor 4, ineffability.
The three-factor “Hood” model was based on empirical fac-
tors derived from the HMS (Hood, 1975) and applied as a plausi-
ble alternative model for the items of the MEQ30 (MacLean
et al., 2012). In the three-factor “Hood” model, items 2, 6, 12, 15,
23, 29, 34, 35, 41, 48, 54, 65, 77, 83, and 86 from the MEQ43 (a
subset of items from the transcendence of time and space, inef-
fability, and internal unity factors of the MEQ43) loaded onto an
introvertive factor; items 14, 47, and 74 from the MEQ43 (a sub-
set of items from the external unity factor of the MEQ43) loaded
onto an extrovertive factor; and items 5, 9, 18, 22, 30, 43, 69, 36,
55, 73, 80, and 87 from the MEQ43 (a subset of items from the
positive mood, sacredness, and noetic quality factors of the
MEQ43) loaded onto an interpretation factor. The final three-
factor “Stace,” which is an alternate interpretation of the three-
factor “Hood” model, is identical to the “Hood” model, except
that items 6, 23, and 86 from the ineffability factor of the MEQ43
were moved from the introvertive factor to the interpretation fac-
tor (MacLean et al., 2012). Model fit indexes were compared to
determine the best-fitting model out of these three alternatives.
An additional confirmatory factor model was fit for the
MEQ30, extending the best-fitting factor model by adding an
additional second-order latent variable (MEQ30-total) that can
account for the correlations between the first-level latent varia-
bles from the best-fitting model. For example, if the MEQ30
model was shown to be the best-fitting model (over the “Stace”
and “Hood” three-factor models), the second-order latent varia-
ble MEQ30-total model would be defined as having all four
latent variables (factors) of the MEQ30 model (mystical, positive
mood, transcendence of time and space, and ineffability) loading
onto MEQ30-total.
Structural equation modeling was used to establish the exter-
nal and convergent validity of latent variable (i.e., factor) scores
of the MEQ30.The best-fitting confirmatory factor model was
extended by adding a structural regression. Responses to four
items in the persisting effects questionnaire (personal meaning-
fulness, spiritual significance, change in well-being, and positive
behavior change) were regressed on the latent variable scores for
the MEQ30 and the ratings of intensity of drug effect. Separate
models were fit using either the HRS intensity factor or the HRS
“intensity” item (item 99) as measures of the intensity of drug
effect. These structural equation models were repeated by
regressing responses to items in the persisting effects question-
naire on the second-order latent variable (MEQ30-total) and the
intensity of drug effect.
Confirmatory factor analyses and structural equation models
were fit with maximum likelihood estimation using the lavaan
toolbox (Rosseel, 2012) in the R statistical package (R Core
Team, 2013). Model identification and latent variable scaling for
the second-order factor model was achieved by setting the load-
ing of the first item for each latent variable to 1. Model fit was
evaluated using the comparative fit index (CFI) and the standard-
ized root mean square residual (SRMR; Bentler, 1995; Hu and
Bentler, 1999). Change in the chi-square goodness-of-fit index
between CFA models is also reported.
CFI may be considered an indicator of acceptable model fit
(Brown, 2006), and consideration of a combination of fit indexes,
with “acceptable fit” values of SRMR <0.09 and CLI >0.90, has
been shown to minimize both type I and type II error, even in
models of small samples (n250; Hu and Bentler, 1999). A com-
monly used model fit index, root mean square error of approxi-
mation (RMSEA; Browne and Cudeck, 1993), has been shown to
both over-reject true-population models and under-reject mis-
specified models when the sample size is small (n250), and
therefore it was not considered here (Hu and Bentler, 1999).
Given the small sample size, chi-square (and, by extension, CFI)
was calculated using the used the Satorra–Bentler scaled test sta-
tistic (Satorra and Bentler, 2001).
Adaptation of a scoring method for complete mystical expe-
rience. The MEQ43 can be scored to yield a dichotomous clas-
sification of “complete mystical experience.” Observations with
a score 60% of the maximum possible score on each of the
subscales of the MEQ43, discarding the lower score of either
internal unity or external unity (yielding a classification based on
six of the seven scales of the MEQ43), are considered a complete
mystical experience (Griffiths et al., 2006). This classification
approach was adapted to the MEQ30. Observations on the
MEQ30 that had a score 60% of the maximum possible score
on each of the four subscales of the MEQ30 were considered a
“complete mystical experience.” In the case of the MEQ30, dif-
ferences in scores for the previously identified internal unity or
external unity scales were not considered because items from
both of these scales load onto the mystical factor in the MEQ30.
For comparison, “complete mystical experience” classifica-
tions were calculated separately using six factors of the MEQ43
and four factors of the MEQ30, and these two methods of classi-
fication were compared. Classification statistics of the complete
mystical scorings derived from the MEQ30 were assessed, using
the classifications of complete mystical experience derived from
the MEQ43 as the ground truth. Classification statistics consist of
a contingency table (true positive, TP; false positive, FP; true
negative, TN; and false negative, FN, observations), hit rate (TP/
[TP+FN]), false alarm rate (FP/[FP+TN]), proportion correct
([TP+TN]/[TP+TN+FP+FN]), and the index of sensitivity (d′) of
the MEQ30-derived scores (Macmillan and Creelman, 2005).
Results
Internal validity of the MEQ30
Comparison of model fit indexes between the four-factor
MEQ30 model, the three-factor “Stace” model, and the three-
factor “Hood” model for MEQ30 data replicated previous find-
ings of best fit for the four-factor MEQ30 model (MacLean
et al., 2012). Specifically, the four-factor MEQ30 model dem-
onstrated acceptable model fit (CFI >0.90, SRMR <0.09), while
both the Stace and Hood models demonstrated poor model fit
(CFI <0.90; Table 1). Standardized confirmatory factor load-
ings and factor correlations for the four-factor MEQ30 model
at JOHNS HOPKINS UNIVERSITY on October 8, 2015jop.sagepub.comDownloaded from
Barrett et al. 5
are reported in Figure 1. The four factors of the MEQ30
displayed excellent reliability, calculated using Cronbach’s
alpha (αmystical=0.97, αpositive mood=0.92, αtrans.time/space=0.86,
αineffability=0.90). Factor loadings for the four-factor MEQ30
model show high loading of each item onto its intended factor,
and support the internal validity of the instrument. Factor load-
ings and correlations are similar to those reported in the devel-
opment of the MEQ30 (MacLean et al., 2012), with the
exception of a lower factor loading in the current sample (0.46)
compared with the previously reported loading (0.70) of
MEQ30 item #11. This factor loading would have met inclusion
criteria in the original publication (MacLean et al., 2012).
Therefore, no modifications of the questionnaire or factor
model were introduced.
An additional model was fit (the MEQ30-total model) with all
four latent variables (mystical, positive mood, transcendence of
time and space, and ineffability) loading onto a second-order
latent variable (MEQ30-total). This model is consistent with the
theoretical and philosophical literature on mystical experience
that proposes an underlying generative experience that is manifest
Table 1. Model fit for confirmatory factor analyses.
Model CFI SRMR χ2 (df) χ2 (∆df)
Stace (3 factors) 0.829 0.074 1068.43 (402)
Hood (3 factors) 0.839 0.071 1029.99 (402) 38.44 (0)***
MEQ30 (4 factors) 0.906 0.062 767.40 (399) 262.59 (3)***
MEQ30 total 0.900 0.068 790.86 (401) 23.46 (2)***
χ2 and CFI are corrected using the Satorra–Bentler scaling (Satorra and Bentler,
2001).
***p<0.001.
CFI, comparative fit index; SRMR, standardized root mean square residual.
Figure 1. Confirmatory factor structure and factor correlations for the four-factor, 30-item Mystical Experience Questionnaire (MEQ30). For each
factor loading, 95% confidence intervals were estimated using bootstrapping in the lavaan toolbox in the R statistical package, and are presented
in square brackets next to each factor loading. The States of Consciousness Questionnaire (SOCQ) item number and the MEQ30 item number for each
item is presented at the end of the text for that item. Factor loadings are standardized.
at JOHNS HOPKINS UNIVERSITY on October 8, 2015jop.sagepub.comDownloaded from
6 Journal of Psychopharmacology
in multiple facets (e.g., unity, positive mood, transcendence of
time and space, and ineffability). This model demonstrated
acceptable fit (MEQ30-total; Table 1), supporting the existence of
a second-order MEQ30 total score variable.
External validity of the MEQ
The two MEQ30 models above (the four-factor MEQ30 model and
the MEQ30-total model) were extended by adding a structural
regression to each model. The structural MEQ30 model consisted
of multivariate regression of each of four items from the persisting
effects questionnaire (personal meaningfulness, spiritual signifi-
cance, change in well-being or life satisfaction, and positive behav-
ior change attributed by the volunteer to the psilocybin session
experience) on the mystical, positive mood, transcendence of time
and space, and ineffability latent variables, and the rated intensity
of drug effects (using either the intensity factor or intensity item,
item 99, from the HRS). The structural MEQ30-total model con-
sisted of a regression of each of the persisting effects items on the
MEQ30-total latent variable and the rated intensity of drug effects.
Both the structural MEQ30 model (CFI=0.905, SRMR=0.058)
and the structural MEQ30-total model (CFI=0.900, SRMR=0.060)
demonstrated acceptable model fit. The HRS intensity item
responses did not predict outcome measures in either model.
Latent variable scores for the mystical factor of the MEQ30 posi-
tively predicted the retrospectively rated spiritual significance of
the session experience (Figure 2). Scores on the mystical factor
also predicted positive changes in behavior attributed to the ses-
sion (B=0.465, z=2.576, p=0.010). Latent variable scores for the
positive mood factor of the MEQ30 predicted ratings of increased
sense of personal well-being attributed to the session (B=0.315,
z=2.197, p=0.028). No first-level latent variable scores (mystical,
positive mood, transcendence of time and space, and ineffability)
were predictive of the rated meaningfulness of the experience.
The MEQ30-total latent variable scores significantly and posi-
tively predicted each outcome variable (Figure 3).
Scoring complete mystical experiences
The contingency tables comparing classification of “complete”
mystical experience derived from the MEQ30 to classifications
of “complete” mystical experience derived from the MEQ43 are
presented in Table 2. The hit rate (0.95), false alarm rate (0.14),
proportion correct (90.2%), and sensitivity (d′=3.464) for com-
plete mystical experience scores derived from the MEQ30 fac-
tors indicate that this scoring is comparable to the scoring of
complete mystical experience scores derived from the MEQ43,
with the MEQ30 exhibiting a slight bias toward scoring more
observations as mystical experiences than the MEQ43.
MEQ43 and MEQ30 factor scores for “false alarm” cases
(where the MEQ30 factor scores indicate a “complete mystical
experience” but the MEQ43 factor scores do not) are presented
in Table 3. Closer inspection reveals that each case of a false
alarm for complete mystical experience using the MEQ30 factor
scores (n=14) can be traced to a sub-threshold score on a single
scale of the MEQ43. The positive mood factor of the MEQ43
contributed a sub-threshold score for the greatest number false
alarm observations (n=5), but all other MEQ43 factors contrib-
uted a sub-threshold score in at least one false-alarm case (inef-
fability=3 cases, noetic=2 cases, unity=2 cases, sacredness=1
case, transcendence of time and space=1 case).
Discussion
For this study, end-of-session ratings of mystical experience and
intensity of drug effects, as well as longitudinal ratings of persist-
ing effects of psilocybin, were combined across five laboratory
experiments. Factor analyses of the items that comprise the
MEQ30 support the internal validity of this instrument. Structural
equation models support the external validity of latent variable
scores on the MEQ30 by demonstrating a significant relationship
between MEQ30 latent variable scores (specifically the mystical,
positive mood, and MEQ30-total variables) and persisting effects
of psilocybin sessions, when controlling for the possible effects
of drug intensity on these outcome measures.
The theoretical basis of a one-factor second-level latent struc-
ture to the MEQ30 (supporting an MEQ30-total score) lies in the
fact that the dimensions of mystical experience outlined by Stace
(1960) and codified in the MEQ are theorized to represent expres-
sions of an underlying (latent) unitary mystical experience. The
one-factor solution to the MEQ30 in fact represents a quantitative
test of this theory, modeling a second-level latent variable that pre-
dicts each of the four first-level latent variables (mystical, positive
mood, ineffability, and transcendence of time and space). Only two
of dimensions of the four-factor model of the MEQ30 (mystical and
positive mood) show predictive validity when regressing the retro-
spective ratings of psilocybin sessions, while the MEQ30-total
score showed predictive validity for all retrospective ratings. The
MEQ30-total score having the greatest predictive validity is con-
sistent with the premise of a latent mystical experience that drives
Figure 2. Retrospective ratings of the spiritual significance of
psilocybin sessions are predicted by MEQ30 “mystical” factor scores.
Retrospective ratings were provided three to eight weeks after each
psilocybin session. MEQ30 ratings were provided seven hours after
capsule administration. The line of best fit is plotted through the
scatterplot. The standardized regression coefficient (B) from the
structural equation model and the associated z- and p-values for this
relationship are superimposed on the figure.
at JOHNS HOPKINS UNIVERSITY on October 8, 2015jop.sagepub.comDownloaded from
Barrett et al. 7
change in each proposed subscale of mystical experience, and it
supports the idea that retrospective ratings of psilocybin experi-
ences and persisting effects that are attributed to those experiences
would most strongly be predicted by a measure that incorporates
signal from all proposed dimensions of mystical experience.
Mystical experiences are defined as having a number of
dimensions (unity, sacredness, noetic quality, ineffability, positive
mood, transcendence of time and space), in which the experience
of any one of those dimensions alone does not constitute a classic
“mystical” experience (Stace, 1960). A scoring system for “com-
plete mystical experiences” derived from the four MEQ30 factor
Figure 3. Retrospective ratings of psilocybin sessions are predicted by the MEQ-total factor score. Retrospective ratings were provided three to
eight weeks after each psilocybin session. MEQ30 ratings were provided seven hours after capsule administration. Lines of best fit are plotted
through each scatterplot. Standardized regression coefficients (B) from the structural equation model and their associated z and p values are
superimposed on each axis. (A and B) Retrospective ratings of the (A) meaningfulness and (B) spiritual significance of psilocybin sessions are
plotted against standardized MEQ30-total scores. (C and D) Retrospective ratings of (C) change in well-being and (D) positive behavior change
attributed to psilocybin sessions are plotted against standardized MEQ30-total scores.
Table 2. Contingency table comparing complete mystical experience
classifications between MEQ43-derived classification and MEQ30-
derived classification.
MEQ43 factors
Positive Negative
MEQ30 factors Positive 80 14 94
Negative 4 86 90
84 100 N=184
at JOHNS HOPKINS UNIVERSITY on October 8, 2015jop.sagepub.comDownloaded from
8 Journal of Psychopharmacology
scores is demonstrated, and provides a rough classification of a
“complete” mystical experience equivalent to the six-factor scor-
ing system for the MEQ43 that has been used in previous research
(Griffiths et al., 2006, 2011). Though the false-alarm rate (14%)
for classification of complete mystical experiences using the
MEQ30 factor scores relative to the MEQ43 factor scores is nota-
ble, each false-alarm case may be more likely due to greater sen-
sitivity (ability to detect true positives) of the MEQ30 relative to
the MEQ43, rather than a decrease in specificity (ability to iden-
tify true negatives) of the MEQ30 relative to the MEQ43. Each
case of a false alarm derived from the MEQ30 factor scores is
super-threshold (60% of the total maximum score) for all but
one scale score of the MEQ43, and the one sub-threshold MEQ43
scale score for each false alarm case is not greatly sub-threshold
(M=0.51, SD=0.046, range 0.43–0.58). Given that the MEQ30
was constructed from the most psychometrically valid and relia-
ble items from the entire MEQ43, it is reasonable to assume that
items not included in the MEQ30 contribute error variance in the
scoring of complete mystical experiences in the MEQ43, and this
could explain potential decreased sensitivity of “complete mysti-
cal” classification using the MEQ43. From this perspective,
removal of weak items in the construction of the MEQ30, and a
greater number of observations being judged “complete mystical
experience” in the MEQ30, can be considered a positive feature of
the revised instrument.
Using a stand-alone version of the MEQ
While the bulk of MEQ data reported to date (Griffiths et al., 2006,
2011; Johnson et al., 2014; MacLean et al., 2012) were collected
using the MEQ43 embedded within the full 100-item SOCQ, the
second study in the original development of the MEQ30 (MacLean
et al., 2012) validated the factor structure of the MEQ30 in a data
set in which only the items of the MEQ43 were presented (not
including the 57 distractor items of the SOCQ). This demonstrates
the robustness of the MEQ30 factor structure against the presence
or absence of the SOCQ distractor items.
In order to replicate the factor structure of the MEQ30 directly
in the absence of SOCQ distractor items (as in MacLean et al.,
2012: study 2), an additional online survey data set was analyzed
(Appendix 1). In this data set, the MEQ43 was presented, rather
than the 100-item SOCQ. Confirmatory factor analysis of the
MEQ30 items from this data set replicated the factor structure of
the MEQ30 as reported in this study and in previous work
(MacLean et al., 2012), providing further evidence that the struc-
ture of this instrument is resilient to the presence or absence of
distractor items from the SOCQ.
A stand-alone version of the MEQ30 is offered in Appendix 2
and is recommended for future experimental use. Though the
MEQ30 has not yet been explicitly validated as a stand-alone
instrument, it has demonstrated resilience against the presence or
absence of distractor items. Considering that the MEQ30 has now
been psychometrically validated in both online survey samples and
experimental laboratory samples, and in reports of both experi-
ences with psilocybin-containing mushrooms and experiences
with controlled-dose psilocybin administrations, use of the MEQ30
is recommended over both the MEQ43 and SOCQ. To facilitate
comparison of future studies utilizing the MEQ30 with previously
publications that reported on ratings of the MEQ43 (Griffiths et al.,
2008, 2011), we provide MEQ30 scores (in Appendix 3) for
MEQ43 ratings provided in these previously published reports.
Relationship between mystical and religious
experience
The mystical experience is not conceptually limited to religious
experience or practice, and the measurement of mystical experience
by the MEQ does not require any direct religious or mystical endorse-
ment. The MEQ serves as a psychometrically sound self-report
instrument that assesses philosophically and theoretically identified
Table 3. Comparison of factor scores on the MEQ43 and MEQ30 for false positive cases of complete mystical experience derived from MEQ30 factor
scores.
False
positive
case
MEQ43 MEQ30
Max. unity Trans time/
space
Ineffability Sacred Noetic Positive
mood
Mystical Positive
mood
Trans time/
space
Ineffability
1 0.63 0.80 1.00 0.83 0.65 0.43 0.73 0.67 0.83 1.00
2 0.97 0.88 1.00 0.80 1.00 0.49 0.97 0.63 0.83 1.00
3 0.93 0.78 0.84 1.00 0.90 0.54 0.97 0.67 0.73 1.00
4 0.70 0.85 0.88 0.60 0.65 0.54 0.71 0.73 0.87 1.00
5 0.60 0.80 0.64 0.60 0.75 0.54 0.61 0.60 0.87 0.73
6 0.77 0.80 0.80 0.66 0.50 0.74 0.61 0.73 0.83 1.00
7 0.63 0.78 0.60 0.74 0.55 0.69 0.67 0.73 0.80 0.67
8 0.83 0.85 0.80 0.51 0.70 0.63 0.68 0.73 0.83 0.80
9 0.63 0.68 0.48 0.77 0.70 0.80 0.73 0.83 0.63 0.67
10 0.67 0.78 0.48 0.80 0.90 0.74 0.85 0.77 0.70 0.67
11 0.93 0.78 0.56 0.86 1.00 0.97 1.00 0.97 0.70 0.93
12 0.90 0.58 0.76 0.97 1.00 0.86 0.97 0.97 0.63 0.80
13 0.43 0.85 1.00 0.86 0.95 0.80 0.76 0.83 1.00 1.00
14 0.53 0.90 0.92 0.89 0.80 0.80 0.65 0.80 1.00 0.87
Scale scores on the MEQ43 and MEQ30 are expressed as the proportion of the maximum possible score on each scale. The “Max. Unity” column contains the maximum
value between the internal unity and external unity scales from the MEQ43, and is considered as the score for the unity factor when determining complete mystical
experiences for the MEQ43. Scores on any scale that fall below 60% of the total maximum score for that scale are presented in bold.
at JOHNS HOPKINS UNIVERSITY on October 8, 2015jop.sagepub.comDownloaded from
Barrett et al. 9
facets of mystical experiences and, by virtue of scores on these
dimensions, can characterize the degree to which a given experi-
ence fits the schema of “mystical.”
Conclusion
Although the biological mechanisms underlying mystical experi-
ences have not been identified, mystical experiences have a clear
operational definition (Griffiths et al., 2006, 2011; MacLean
et al., 2012; Pahnke, 1963; Richards, 1975), and the value of
mystical experiences in terms of predicting positive outcomes
has been empirically demonstrated (Griffiths et al., 2006, 2008,
2011; Johnson et al., 2014; MacLean et al., 2011). The present
study contributes to this literature by demonstrating the psycho-
metric fitness in prospectively obtained experimental data of an
instrument that was developed to assess individual mystical
experiences (the MEQ30). These findings extend this literature
by demonstrating the value of scores on the MEQ30 over a sim-
ple measure of intensity of drug effects in predicting positive out-
comes related to mystical experiences occasioned by psilocybin.
Given the predictive validity of MEQ30-total scores in the cur-
rent sample, researchers should use the MEQ30-total score over
MEQ30 factor scores (identified by the mystical, positive mood,
transcendence of time and space, or the ineffability factors) in
future investigations of mystical experience, unless they have
specific hypotheses regarding the predictive validity of specific
dimensions of mystical experience.
Validation of the MEQ30 in experimental data constitutes an
important step in developing this questionnaire instrument for
use in pharmacological studies of mystical experiences. Further
experimental work should validate the MEQ30 in studies of mys-
tical experiences encountered through other means. On the basis
of these findings, we recommend use of the MEQ30 for future
investigations of individual episodes of mystical experiences.
Declaration of Conflicting Interests
The authors declared the following potential conflicts of interest
with respect to the research, authorship, and/or publication of this article:
Dr Griffiths is on the board of directors of the Heffter Research Institute,
a funding sponsor for some of the studies included in this report.
Funding
The authors disclosed receipt of the following financial support for the
research, authorship, and/or publication of this article: This research was
supported by the National Institutes of Health [grant numbers R01
DA03889, T32 DA007209], and grants from the Heffter Research
Institute and the Council on Spiritual Practices.
References
Bentler PM (1995) EQS Structural Equations Program Manual. Encino,
CA: Multivariate Software.
Bogenschutz MP, Forcehimes AA, Pommy JA, et al. (2015) Psilocybin-
assisted treatment for alcohol dependence: a proof-of-concept study.
J Psychopharmacol 29: 289–299.
Brown TA (2006) Confirmatory Factor Analysis for Applied Research.
New York: Guilford Press.
Browne MW and Cudeck R (1993) Alternative ways of assessing model
fit. In: Bollen KA and Long JS (eds) Testing Structural Equation
Models. Newbury Park, CA: Sage, pp.136–162.
Chen Z, Hood RW, Yang L, et al. (2011a) Mystical experience among
Tibetan Buddhists: the common core thesis revisited. J Scient Study
Religion 50: 328–338.
Chen Z, Wen Q, Hood RW, et al. (2011b) Common core thesis and quali-
tative and quantitative analysis of mysticism in Chinese Buddhist
monks and nuns. J Scient Study Religion 50: 654–670.
Chen Z, Zhang Y, Hood RW, et al. (2012) Mysticism in Chinese Chris-
tians and non-Christians: measurement invariance of the mysticism
scale and implications for the mean differences. Int J Psychol Reli-
gion 22: 155–168.
Garcia-Romeu A, Griffiths RR and Johnson MW (2015) Psilocybin-
occasioned mystical experiences in the treatment of tobacco addic-
tion. Current Drug Abuse Rev 7: 157–164.
Griffiths R, Richards W, Johnson M, et al. (2008) Mystical-type experi-
ences occasioned by psilocybin mediate the attribution of personal
meaning and spiritual significance 14 months later. J Psychophar-
macol 22: 621–632.
Griffiths RR, Johnson MW, Richards WA, et al. (2011) Psilocybin occa-
sioned mystical-type experiences: immediate and persisting dose-
related effects. Psychopharmacology (Berl) 218: 649–665.
Griffiths RR, Richards WA, McCann U, et al. (2006) Psilocybin can
occasion mystical-type experiences having substantial and sustained
personal meaning and spiritual significance. Psychopharmacology
(Berl) 187: 268–283; discussion 284–292.
Hood RW (1975) The construction and preliminary validation of a measure
of reported mystical experience. J Scient Study Religion 14: 29–41.
Hood RW, Ghorbani N, Watson PJ, et al. (2001) Dimensions of the
mysticism scale: confirming the three-factor structure in the United
States and Iran. J Scient Study Religion 40: 691–705.
Hood RW Jr, Hill PC and Spilka B (2009) The Psychology of Religion:
An Empirical Approach. 4th ed. New York, NY: Guilford.
Hu L and Bentler PM (1999) Cutoff criteria for fit indexes in covari-
ance structure analysis: conventional criteria versus new alternatives.
Struct Eq Model: Multidis J 6: 1–55.
James W (1902) The Varieties of Religious Experience: A Study in
Human Nature. New York: Random House.
Johnson MW, Garcia-Romeu A, Cosimano MP, et al. (2014) Pilot study
of the 5-HT2AR agonist psilocybin in the treatment of tobacco
addiction. J Psychopharmacol 28: 983–992.
MacLean KA, Johnson MW and Griffiths RR (2011) Mystical experiences
occasioned by the hallucinogen psilocybin lead to increases in the
personality domain of openness. J Psychopharmacol 25: 1453–1461.
MacLean KA, Leoutsakos JM, Johnson MW, et al. (2012) Factor analysis of
the Mystical Experience Questionnaire: a study of experiences occasioned
by the hallucinogen psilocybin. J Scient Study Religion 51: 721–737.
Macmillan NA and Creelman CD (2005) Detection Theory: A User’s
Guide. 2nd ed. Mahwah, NJ: Lawrence Erlbaum.
Pahnke WN (1963) Drugs and Mysticism: An Analysis of the Relation-
ship Between Psychedelic Drugs and the Mystical Consciousness.
Cambridge, MA: Harvard University Press.
Pahnke WN (1967) LSD and religious experience. In: DeBold RC and
Leaf RC (eds) LSD Man & Society. Middletown, CT: Wesleyan
University Press, pp.60–85.
R Core Team (2013) R: A Language and Environment for Statistical Com-
puting. Vienna, Austria: R Foundation for Statistical Computing.
Richards WA (1975) Counseling, Peak Experiences and the Human Encoun-
ter with Death: An Empirical Study of the Efficacy of DPT-Assitance
Counseling in Enhancing Quality of Life of Persons with Terminal Can-
cer and Their Closest Family Members. Los Angeles, CA: UCLA.
Richards WA, Rhead JC, Dileo FB, et al. (1977) The peak experience
variable in DPT-assisted psychotheraphy with cancer patients.
J Psyched Drugs 9: 1–10.
Rosseel Y (2012) lavaan: an R Package for structural equation modeling.
J Statist Softw 48(2): 1–36.
Satorra A and Bentler PM (2001) A scaled difference chi-square test
statistic for moment structure analysis. Psychometrika 66: 507–514.
Stace WT (1960) Mysticism and Philosophy. New York: MacMillan
Press.
Strassman RJ, Qualls CR, Uhlenhuth EH, et al. (1994) Dose–response
study of N,N-dimethyltryptamine in humans. II. Subjective effects and
preliminary results of a new rating scale. Arch Gen Psych 51: 98–108.
at JOHNS HOPKINS UNIVERSITY on October 8, 2015jop.sagepub.comDownloaded from
... 33 Feelings of "timelessness" or experiences of "eternity" have even been described by many. 34 Beyond these sensory alterations, the subjective experience of perception is often enhanced by a surge of curiosity and amazement. This typically translates into the adoption of a contemplative stance, through which the perception of beauty can be expanded. ...
... These internal phenomena can sometimes be felt as "more real than reality". 34 Akin to revelations of great importance, many consider these experiences with reverence and strive to remember their details. Culturally loaded terms such as "sacred" or "mystical" are often used to describe these subjective experiences. ...
... Thoughts and feelings of being united with something that transcends the personal self are cardinal features of many psychedelic experiences, 34,35 and terms such as "oceanic boundlessness" have been used to describe these profound experiences of connection with a larger whole. These experiences of unity may be characterized by a blurring of the boundary between the external environment and what is commonly considered the "I" or the "self." ...
Article
Full-text available
Psilocybin therapy has recently emerged as a promising new treatment for depression and other mental health disorders. This chapter summarizes the most recent data on its safety and efficacy. The delivery of psilocybin therapy and its subjective effects are also presented. Furthermore, this chapter outlines our current understanding of psilocybin’s pharmacology and neurobiological effects. Other similar psychedelic substances with encouraging therapeutic potential are briefly presented.
... The revised 30-item MEQ is a self-report measure used to assess the acute mystical-type experience via a 6-point Likert scale and grouped into four subscales: Mystical Positive Mood, Transcendence of Time and Space, and Ineffability. These have displayed excellent reliability (α =.97, α =.92, α =.86, α =.90, respectively) in recent studies within controlled psilocybin studies (Barrett et al., 2015). The translation into Spanish by Bouso et al. (2016a) was used in this study. ...
... There was a significant high negative correlation found between the Flourishing Index and AAQ scale, indicating a high divergence between these two scales. Initial analysis produced a three-factor structure for the MEQ rather than the expected four factor structure the English version has consistently produced (Barrett et al., 2015;Davis et al., 2023;MacLean et al., 2012). When evaluating the obtained variable loading, all loaded parsimoniously with a single factor. ...
Article
Recent research into psychedelics has found them to be an effective treatment for disorders related to depression, anxiety, and post traumatic stress disorder. Mystical experiences have proven to mediate the therapeutic effects for outcomes; however, Spanish measures have not been studied thoroughly. In this study we explored the psychometric properties of the Mystical Experience Questionnaire (MEQ), Acceptance and Action Questionnaire-II (AAQ-II), and VanderWeele’s Flourishing Measure in a Spanish-speaking sample in Puerto Rico. The MEQ is a 30-item questionnaire that measures the degree of a mystical experience. A total of 235 participants took part in a survey where they answered the MEQ and other well-being questionnaires concerning past or future psychedelic use. For psychometric analysis, 207 participant answers were used for Exploratory Factor Analysis (EFA) and internal consistency. EFA revealed a three-factor structure explaining 65.46% of the variance and displayed high internal consistency for each scale (whole scale McDonald’s ωt=.98) of the MEQ. Furthermore, other well-being scales also displayed high internal consistency. The Spanish translation of the MEQ and other well-being scales demonstrated to be appropriate measures for the assessment of mystical experiences, psychological flexibility, and flourishing in a Spanish-speaking sample with and without the use of psychedelics.
... Observations of similar effects in the domain of cognition-cf. the "noetic" quality of mystical experiences (Barrett et al. 2015)-suggest that SEBUS effects may parsimoniously apply to belief dynamics at multiple levels of abstraction. ...
Article
Full-text available
How is it that psychedelics so profoundly impact brain and mind? According to the model of “Relaxed Beliefs Under Psychedelics” (REBUS), 5-HT2a agonism is thought to help relax prior expectations, thus making room for new perspectives and patterns. Here, we introduce an alternative (but largely compatible) perspective, proposing that REBUS effects may primarily correspond to a particular (but potentially pivotal) regime of very high levels of 5-HT2a receptor agonism. Depending on both a variety of contextual factors and the specific neural systems being considered, we suggest opposite effects may also occur in which synchronous neural activity becomes more powerful, with accompanying “Strengthened Beliefs Under Psychedelics” (SEBUS) effects. Such SEBUS effects are consistent with the enhanced meaning-making observed in psychedelic therapy (e.g. psychological insight and the noetic quality of mystical experiences), with the imposition of prior expectations on perception (e.g. hallucinations and pareidolia), and with the delusional thinking that sometimes occurs during psychedelic experiences (e.g. apophenia, paranoia, engendering of inaccurate interpretations of events, and potentially false memories). With “Altered Beliefs Under Psychedelics” (ALBUS), we propose that the manifestation of SEBUS vs. REBUS effects may vary across the dose–response curve of 5-HT2a signaling. While we explore a diverse range of sometimes complex models, our basic idea is fundamentally simple: psychedelic experiences can be understood as kinds of waking dream states of varying degrees of lucidity, with similar underlying mechanisms. We further demonstrate the utility of ALBUS by providing neurophenomenological models of psychedelics focusing on mechanisms of conscious perceptual synthesis, dreaming, and episodic memory and mental simulation.
... (scored as 1-7 Likert scale with 1 = Extremely positive, 4 = Neither positive nor negative, and 7 = Extremely negative). Participants also completed the 30-item Mystical Experience Questionnaire (MEQ; total scores scaled 0-5, with higher scores indicating greater degree of mystical-type experience) (Barrett, Johnson, and Griffiths 2015), the 26-item Challenging Experience Questionnaire (CEQ; total scores scaled 0-1, with higher scores indicating greater degree of challenging experience) , and the 10-item State Shame and Guilt Scale measuring state shame and guilt (SSGS-Shame/SSGS-Guilt; each subscale scored 5-25, with higher scores indicating greater experiences of shame and guilt, respectively) (Held, Owens, and Anderson 2015;Marschall 1997). The SSGS prompt was adapted to ask individuals about these feelings specifically during psilocybin use. ...
Article
Full-text available
The classic psychedelic psilocybin has attracted special interest across clinical and non-clinical settings as a potential tool for mental health. Despite increasing attention to challenging psychedelic experiences, few studies have explored the relevance of shame-related processes with psychedelic use. This prospective, longitudinal study involved sequential, automated, web-based surveys that collected data from 679 adults planning to use psilocybin in naturalistic settings at timepoints before and after psilocybin use. State and trait shame and feelings of guilt were collected using validated measures and assessed alongside other measurements of psychological health. Acute feelings of shame or guilt during psilocybin experiences were commonly reported (68.2% of users) and difficult to predict. Ratings of participant ability to constructively work through these feelings predicted wellbeing 2–4 weeks after psilocybin use. Psilocybin on average produced a small but significant decrease in trait shame that was maintained 2–3 months after use (Cohen’s dz = 0.37). Trait shame increased in a notable minority of participants (29.8%). The activation of self- conscious emotions with psychedelics deserves further attention as a challenging experience subcategory that may be relevant to psychological outcomes. Such experiences could pose a unique and context-dependent learning condition for both therapeutic and detrimental forms of shame-related memory reconsolidation.
... Often dubbed 'the second wave' of psychedelic research [95], these studies have largely replaced psychomimetic framings with neutral or highly positive language and measurement instruments [96]. These include the Altered States of Consciousness rating scale [97], the Mystical Experience Questionnaire [98], and the Emotional Breakthrough Inventory [99], with scores on the latter two questionnaires being associated with lasting benefits in multiple studies [99][100][101][102]. ...
Introduction: Since its synthesis in 1962, ketamine has been widely used in diverse medical contexts, from anesthesia to treatment-resistant depression. However, interpretations of ketamine's subjective effects remain polarized. Biomedical frameworks typically construe the drug's experiential effects as dissociative or psychotomimetic, while psychedelic paradigms emphasize the potential therapeutic merits of these non-ordinary states. Areas covered: Ketamine's psychoactive effects have inspired diverse interpretations. In this review, we trace the historical evolution of these perspectives - which we broadly categorize as 'dissociative,' 'dream-like,' and 'psychedelic' - and show how they emerged out of these clinical contexts. We highlight the influence of factors such as language, dose, and environmental context on ketamine's effects and therapeutic outcomes. We discuss potential mechanisms underlying these context-dependent effects and explore the broader clinical and research-related ramifications. Expert opinion: Ketamine's subjective effects are undeniably powerful, yet their therapeutic significance remains debated. A nuanced, interdisciplinary approach is essential for maximizing ketamine's potential. Future research should focus on how explanatory models, treatment environments, and patient preparation can optimize ketamine's benefits while minimizing distress. We suggest that, rather than being a tiger to be tamed as its creator once described, ketamine may best be understood as a chameleon whose color shifts depending on its context.
... One of the most intriguing aspects of psychedelic drugs is their ability to enhance meaning (Hartogsohn, 2018), a quality that was brought back to the awareness of mainstream science through the widely cited work of Griffiths, Richards, McCann, and Jesse (2006), who showed that psilocybin can occasion mystical experiences, that are not only deeply meaningful but also have a long-lasting impact on personality. As operationalized by the Mystical Experience Questionnaire, these are profound, meaningful experiences characterized by a sense of unity, sacredness, intuitive knowledge, transcendence of time and space, deeply felt positive mood, and ineffability (Barrett, Johnson, & Griffiths, 2015). Carhart-Harris et al. (2014) showed that the psychedelic state is characterized by unconstrained cognition and high-entropy neurodynamic and that when the person is shifting back to his/her ordinary state of consciousness, his/her brain is going through a process of reorganization (entropy-suppression). ...
Article
Full-text available
Background While psychedelic substances are extensively studied through the lens of various academic disciplines, their impact on the therapeutic practice of mental health professionals is yet to be explored. This firsthand experience is deemed crucial for effectively assisting patients in the process of integrating a psychedelic experience. Aims The aim of this study was to explore the psychological and spiritual dimensions of psychedelic integration among mental health professionals, focusing on understanding how transformation and insights influence their clinical work. Methods Utilizing a phenomenological methodology, interviews with eight mental health professionals with substantial first-person experience with psychedelics were conducted. Results Our findings indicate a potential, enduring, positive impact of psychedelic meta-integration on the practice of mental health clinicians. The data analysis yielded a multi-faceted model encompassing key aspects of human life including interpersonal and emotional development, relationship with death and nature, concepts of love, meaning, and spirituality, along with elements pertinent to therapeutic work. This comprehensive model integrates these diverse dimensions, offering a holistic understanding of the impact of psychedelics on both personal and professional realms. Conclusions The findings of this study lend support to the notion that health professionals involved in clinical work encompassing psychedelic integration should themselves have undergone induced altered states of consciousness, not only for a better empathetic understanding. This might be also predicated on the intrinsic positive transformative effects on their human capacities and as therapists. This dual benefit underscores the importance of personal experience in the effective facilitation of psychedelic integration in clinical settings.
Article
Full-text available
Introduction: Serotonergic psychedelics, serotonin 2A receptor agonists such as psilocybin that can result in substantially altered states of consciousness, are used in recreational and research settings. The safety of psychedelic experiences in research settings is supported by controlled physical environments, presence of clinical and medical staff to address emergent issues, screening for personal and family history of potential contraindications, and psychoeducational preparation with psychological support. Research settings typically provide psychoeducation to participants verbally and in writing (e.g., informed consent), and such documents and conversations can provide safety-related information—but may also introduce a wide range of expectancies. Such expectancies might involve the specific character of the acute subjective effects of psychedelics, possible side effects, and anticipated outcomes. Methods: To better understand the content of this psychoeducation, we gathered study materials from many psilocybin studies conducted in the past two decades in healthy and therapeutic populations. We conducted a reflexive thematic analysis to better understand these documents. Results: While these documents varied substantially between studies, we identified themes intended to lower levels of risk and optimize therapeutic effects from psychedelic treatments. The most frequently coded themes related to (1) biological and physical safety, (2) psychological safety and well-being, (3) aspects of setting, and (4) potential for expectancies. Prioritizing biological and psychological safety was evident in the materials from all sites. Furthermore, we identify potential contributors to expectancy unrelated to safety and suggest that these extrapharmacological elements be studied systematically in future research. Conclusions: Ideally, future research should strive to maximize safety while attempting to minimize extraneous expectancies.
Article
Full-text available
Rationale To examine the acute effects of ayahuasca use and their relationship to sub-acute changes in affect and mindfulness in a non-clinical sample, addressing the need for a better understanding of ayahuasca’s immediate and short-term impacts as interest in its use grows. Objectives Using prospective ecological assessment, this study investigates how ayahuasca used at a 4-day retreat affects positive/negative affect and mindfulness skills in daily living compared to pre-retreat. Additionally, we explore acute psychedelic experiences during the ayahuasca retreat, assessed retrospectively 1–2 days post-retreat, as potential mechanisms for theorized effects in daily living post-retreat. Methods Thirty-six participants reported positive/negative affect and mindfulness skills three times daily for 5 days before and after the retreat. Baseline assessments included lifetime psychedelic experience, and post-retreat assessments covered acute ayahuasca experiences. Mixed-effect linear models were used to analyze the data. Results Post-retreat, we observed reduced negative affect, increased positive affect, and enhanced mindfulness skills in daily living. Ayahuasca-induced acute experiences, such as time/space transcendence, emotional breakthrough and challenging experiences predicted greater subacute positive affect. Notably, none of these experiences were linked to subacute improvements in negative affect or mindfulness. No participants showed clinically significant adverse responses post-retreat, and only 5.5% exhibited some degree of potentially clinically significant deterioration in affect. Conclusions Ayahuasca use may lead to improvement in mood and mindfulness skills, and key acute psychedelic experiences induced by ayahuasca may be important to some of these salutary effects, positive affect in particular.
Article
Full-text available
Rationale Psychedelic-assisted therapy is increasingly applied within mental health treatment. Objectives This study focused on factors moderating changes in the acute and long-term effects of an individual psilocybin-assisted program on depression, anxiety, PTSD and personality structures by including demographic factors, subjective experience and degree of mystical type experiences during the dosing, as well as emotional breakthrough and personal growth after the program. Methods At baseline, 1 week and 3 months after the psilocybin program participants completed the Generalized Anxiety Disorder Assessment (GAD-7), Patient Health Questionnaire (PHQ-9), PTSD Checklist for DSM-5 (PCL-5) and NEO Five-Factor Inventory-3 (NEO-FFI-3). In addition, after the dosing the Mystical Experiences Questionnaire (MEQ-30), Posttraumatic Growth Inventory (PTGI) and Emotional Breakthrough Inventory (EBI) were administered. Moderation effects were established using linear mixed-model analysis. Results A single high dose of psilocybin in combination with therapy was found to lower symptoms of anxiety, depression, PTSD and neuroticism over a period of 3-months. Scores on openness and conscientiousness increased after the treatment only. Participants reported mystical type experiences, emotional breakthrough and personal growth. These subjective experiences together with demographic factors were moderating the observed positive changes. Conclusions Findings indicate that individual psilocybin-assisted therapy has the potential for beneficial effects on mood and personality characteristics. Moreover, the study highlights the importance of subjective experiences and demographic factors in moderating this effect. This study adds to the ongoing research on psilocybin-assisted therapy by investigating contributing factors for optimizing this evolving type of therapy.
Article
Full-text available
Background: Validation of animal models of hallucinogenic drugs' subjective effects requires human data. Previous human studies used varied groups of subjects and assessment methods. Rating scales for hallucinogen effects emphasized psychodynamic principles or the drugs' dysphoric properties. We describe the subjective effects of graded doses of N,N-dimethyltryptamine (DMT), an endogenous hallucinogen and drug of abuse, in a group of experienced hallucinogen users. We also present preliminary data from a new rating scale for these effects. Methods: Twelve highly motivated volunteers received two doses (0.04 and 0.4 mg/kg) of intravenous (IV) dimethyltryptamine fumarate "nonblind," before entering a doubleblind, saline placebo-controlled, randomized study using four doses of IV DMT. Subjects were carefully interviewed after resolution of drug effects, providing thorough and systematic descriptions of DMT's effects. They also were administered a new instrument, the Hallucinogen Rating Scale (HRS). The HRS was drafted from interviews obtained from an independent sample of 19 experienced DMT users, and modified during early stages of the study. Results: Psychological effects of IV DMT began almost immediately after administration, peaked at 90 to 120 seconds, and were almost completely resolved by 30 minutes. This time course paralleled DMT blood levels previously described. Hallucinogenic effects were seen after 0.2 and 0.4 mg/kg of dimethyltryptamine fumarate, and included a rapidly moving, brightly colored visual display of images. Auditory effects were less common. "Loss of control," associated with a brief, but overwhelming "rush," led to a dissociated state, where euphoria alternated or coexisted with anxiety. These effects completly replaced subjects' previously ongoing mental experience and were more vivid and compelling than dreams or waking awareness. Lower doses, 0.1 and 0.05 mg/kg, were primarily affective and somaesthetic, while 0.1 mg/kg elicited the least desirable effects. Clustering of HRS items, using either a clinical, mental status method or principal components factor analysis provided better resolution of dose effects than did the biological variables described previously. Conclusions: These clinical and preliminary quantitative data provide bases for further psychopharmacologic characterization of DMT's properties in humans. They also may be used to compare the effects of other agents affecting relevant brain receptors in volunteer and psychiatric populations.
Article
Full-text available
Several lines of evidence suggest that classic (5HT2A agonist) hallucinogens have clinically relevant effects in alcohol and drug addiction. Although recent studies have investigated the effects of psilocybin in various populations, there have been no studies on the efficacy of psilocybin for alcohol dependence. We conducted a single-group proof-of-concept study to quantify acute effects of psilocybin in alcohol-dependent participants and to provide preliminary outcome and safety data. Ten volunteers with DSM-IV alcohol dependence received orally administered psilocybin in one or two supervised sessions in addition to Motivational Enhancement Therapy and therapy sessions devoted to preparation for and debriefing from the psilocybin sessions. Participants' responses to psilocybin were qualitatively similar to those described in other populations. Abstinence did not increase significantly in the first 4 weeks of treatment (when participants had not yet received psilocybin), but increased significantly following psilocybin administration (p < 0.05). Gains were largely maintained at follow-up to 36 weeks. The intensity of effects in the first psilocybin session (at week 4) strongly predicted change in drinking during weeks 5-8 (r = 0.76 to r = 0.89) and also predicted decreases in craving and increases in abstinence self-efficacy during week 5. There were no significant treatment-related adverse events. These preliminary findings provide a strong rationale for controlled trials with larger samples to investigate efficacy and mechanisms. NCT02061293. © The Author(s) 2015.
Article
Full-text available
Psilocybin-occasioned mystical experiences have been linked to persisting effects in healthy volunteers including positive changes in behavior, attitudes, and values, and increases in the personality domain of openness. In an open-label pilot-study of psilocybin-facilitated smoking addiction treatment, 15 smokers received 2 or 3 doses of psilocybin in the context of cognitive behavioral therapy (CBT) for smoking cessation. Twelve of 15 participants (80%) demonstrated biologically verified smoking abstinence at 6-month follow-up. Participants who were abstinent at 6 months (n=12) were compared to participants still smoking at 6 months (n=3) on measures of subjective effects of psilocybin. Abstainers scored significantly higher on a measure of psilocybin-occasioned mystical experience. No significant differences in general intensity of drug effects were found between groups, suggesting that mystical-type subjective effects, rather than overall intensity of drug effects, were responsible for smoking cessation. Nine of 15 participants (60%) met criteria for "complete" mystical experience. Smoking cessation outcomes were significantly correlated with measures of mystical experience on session days, as well as retrospective ratings of personal meaning and spiritual significance of psilocybin sessions. These results suggest a mediating role of mystical experience in psychedelic-facilitated addiction treatment.
Article
A measure of reported mystical experience is presented. This "Mysticism Scale, Research Form D (M scale)," has 32 items, four for each of 8 categories of mysticism initially conceptualized by Stace (1960). Items on this scale are both positively and negatively expressed to avoid problems of response set. A factor analysis of the M Scale indicated two major factors, a general mystical experience factor (20 items) and a religious interpretation factor (12 items). Preliminary evidence indicates that those high on the M Scale have more intrinsic religious motivation as defined by Hoge's (1972) scale, are more open to experience as defined by Taft's (1970) ego permissiveness scale, have more intense religious experience as defined by Hood's (1970) scale, and have moderately higher scores on the L, Hs, and Hy scales of the MMPI.