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The Altered States Database: Psychometric Data of Altered States of Consciousness

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Timo Torsten Schmidt at Freie Universität Berlin
Timo Torsten Schmidt
Hendrik Berkemeyer
Hendrik Berkemeyer
Hendrik Berkemeyer
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The experimental induction of altered states of consciousness (ASC) constitutes a research opportunity to relate changes in phenomenological states to underlying biophysical mechanisms. A variety of pharmacological and non-pharmacological methods were reported to induce consciousness alterations in humans, ranging from the consumption of psychoactive drugs to special breathing techniques or sensory deprivation. Within psychological experiments, the subjective experiences of ASCs are typically quantified with retrospective questionnaires. Here, we introduce a database, termed the Altered States Database (ASDB), comprised of questionnaire data extracted from original research articles. The database contains data from articles published in MEDLINE-listed journals from experimentally induced altered states that were assessed with a specified set of standardized questionnaires. The dataset at hand will allow direct comparisons of the psychological effects of different induction methods as well as meta-analyses to establish induction method specific dose-response relationships.
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DATA REPORT
published: 02 July 2018
doi: 10.3389/fpsyg.2018.01028
Frontiers in Psychology | www.frontiersin.org 1July 2018 | Volume 9 | Article 1028
Edited by:
Michela Balsamo,
Università degli Studi G. d’Annunzio
Chieti e Pescara, Italy
Reviewed by:
Claudio Imperatori,
Università Europea di Roma, Italy
Patrizio E. Tressoldi,
Università degli Studi di Padova, Italy
Daiana Colledani,
Università degli Studi di Padova, Italy
*Correspondence:
Timo T. Schmidt
titoschmi@zedat.fu-berlin.de
Specialty section:
This article was submitted to
Quantitative Psychology and
Measurement,
a section of the journal
Frontiers in Psychology
Received: 07 April 2018
Accepted: 31 May 2018
Published: 02 July 2018
Citation:
Schmidt TT and Berkemeyer H (2018)
The Altered States Database:
Psychometric Data of Altered States
of Consciousness.
Front. Psychol. 9:1028.
doi: 10.3389/fpsyg.2018.01028
The Altered States Database:
Psychometric Data of Altered States
of Consciousness
Timo T. Schmidt 1,2
*and Hendrik Berkemeyer 2
1Neurocomputation and Neuroimaging Unit, Department of Education and Psychology, Freie Universität Berlin, Berlin,
Germany, 2Institute of Cognitive Science, University of Osnabrück, Osnabrück, Germany
Keywords: altered states of consciousness, questionnaires, psychometrics, consciousness, drug effects,
database
The experimental induction of altered states of consciousness (ASC) constitutes a research
opportunity to relate changes in phenomenological states to underlying biophysical mechanisms.
A variety of pharmacological and non-pharmacological methods were reported to induce
consciousness alterations in humans, ranging from the consumption of psychoactive drugs
to special breathing techniques or sensory deprivation. Within psychological experiments, the
subjective experiences of ASCs are typically quantified with retrospective questionnaires. Here,
we introduce a database, termed the Altered States Database (ASDB), comprised of questionnaire
data extracted from original research articles. The database contains data from articles published
in MEDLINE-listed journals from experimentally induced altered states that were assessed with
a specified set of standardized questionnaires. The dataset at hand will allow direct comparisons
of the psychological effects of different induction methods as well as meta-analyses to establish
induction method specific dose-response relationships.
BACKGROUND AND SUMMARY
Scientific interest in altered states of consciousness is as old as the origins of modern psychology.
ASCs have caught the attention of psychologists, philosophers of mind, psychiatrists, and lately
neuroscientists. One reason for this interest is to address the question what should be considered
“normal mental functioning” in a philosophical, as well as in a medical sense and public health
considerations. Particularly, the treatment of psychiatric diseases in which conscious functioning
is pathologically impaired puts strong demands on research to elucidate underlying mechanisms
which could be targeted by new therapies. In this line of research, neuroscientist started to
utilize the experimental induction of ASCs in combination with recordings of brain activity to
elucidate neuronal mechanisms underlying alterations in consciousness. Neuroimaging studies on
hallucinogens such as LSD or psilocybin recently gained significant public attention (Carhart-
Harris et al., 2012, 2016; Muthukumaraswamy et al., 2013; Schmid et al., 2015). But also non-
pharmacological induction methods of ASCs such as meditation, sensory deprivation, or breathing
techniques are moving into the research focus (Corlett et al., 2009).
One intriguing question for current studies is how the phenomenology of ASC experiences
compares between different induction methods, between individuals and how they relate to
pathologic situations such as the phenomenology of schizophrenia or depression. The gold-
standard in quantitative experimental research to measure ASC experiences is the retrospect
assessment with standardized and validated questionnaires (Cardeña et al., 2000; Passie, 2007;
Schmidt and Maji´
c, 2016). Multiple questionnaires have been developed to quantify different
aspects of ASC phenomena. Importantly, it has been emphasized that an ASC is not a mere
quantitative change in a single cognitive function (e.g., elevated arousal). Instead, it is a
multidimensional phenomenon (Tart, 1972; Farthing, 1991; Metzner, 2005; Schmidt and Maji´
c,
2016), meaning that not only one aspect of consciousness is affected, but the relative intensity
Schmidt and Berkemeyer The Altered States Database
of multiple consciousness aspects changes. Such
“phenomenological patterns” can be operationalized as the
factor structure of the applied psychometric assessment, i.e.,
the individual ratings, or factor scores, of a questionnaire.
Such psychometric measures allow direct comparisons between
induction methods, individual’s responses, averaged group
responses, and different experimental settings.
Based on these measures, multiple researchers have attempted
to develop taxonomies for different types of ASC experiences
to infer common underlying mechanisms of their emergence
(Dittrich, 1985; Pekala, 1991; Vaitl et al., 2005; Corlett et al.,
2009). However, such attempts have been limited by a lack
of a comprehensive collection of psychometric data. By now,
the results of these measures can only be found in individual
publications where they are often reported in different formats.
The lack of a central collection of these data has prevented direct
comparisons and meta-analyses.
Here we present the Altered States Database (ASDB), as a
collection of the currently available psychometric data on ASC
experiences from diverse induction methods. The ASDB will
allow meta-analyses to establish dose-response relationships and
direct comparisons of existing data with newly generated data. It
further fosters common standards in the assessment of ASCs for
future research.
METHODS
Data Sources
The ASDB contains data extracted from scientific articles. To
assure high quality of the research reports only data from articles
published with peer-review in MEDLINE-listed journals are
included.
Data from the quantitative assessment of ASC experiences
with standardized questionnaires constitute the data in the
ASDB. Based on previous work, considering validity and
reliability measures as well as questionnaire’s prevalence in
the literature, the ASDB has been limited to data from four
different questionnaires, which can be considered as the standard
tools in ASC research (Passie, 2007; Schmidt and Maji´
c, 2016).
Data from three developmental states of the Altered States of
Consciousness Rating Scale are included due to its high literature
prevalence, summing to six different questionnaires in total.
Table 1 summarizes the factor structure of the six questionnaires.
Data has been included starting from the initial publication of
the individual questionnaires (see Table 1) until end of 2017.
Literature Search
We conducted a systematic literature search to identify all articles
that contain psychometric data derived from the six standardized
questionnaires of interest. First, we used Google Scholar ©
to identify forward citations of the original publications of
the questionnaires and their methodological refinements and
translations (references used in the literature research are
provided in Table 1). Secondly, we discarded review articles
and articles that were not published in MEDLINE-listed peer-
reviewed journals. Next, we manually screened titles and
abstracts to identify articles reporting human research with
FIGURE 1 | Data model for the ASDB. The general data model to store the
psychometric data with comprised entities and relations (simplified).
primary data on the experimental induction of ASCs. Finally,
original articles were accessed, wherever possible, and Methods
and Results sections, as well as supplementary materials, were
screened for psychometric data that were derived from a
described experimental induction of an ASC.
After obtaining a list of induction methods from this search
procedure, we used corresponding search terms together with
search terms of common knowledge to conduct a MEDLINE
search for any mentioning of these induction methods in title,
abstract, or keywords. The list of resulting articles was screened
as described above to include articles which might contain
suitable data while failing to include a reference to the applied
questionnaires.
Extraction of Data
The identified articles reported psychometric data in variable
styles, e.g., in tables, in graphs, or as in-line text. Wherever
numeric values were available, these were directly entered into
the database. Data from figures were extracted manually. Data
reported with standard error were transformed into standard
deviation and rounded to two digits. A second person double-
checked all extracted data.
Several research articles contained non-standardized
measures (e.g., reporting absolute scores instead of mean
responses), which were rescaled/standardized after confirmation
by the authors of the article, where possible. If rescaling was
not possible, data were excluded from the database. Any data
adjustments, as well as reasons for exclusion, are documented
and accessible together with the overall dataset.
Data Model
The database is implemented in MySQL. The collected
questionnaires with corresponding factor/scale structure formed
the basis for the database model. A simplified model is
displayed in Figure 1, which accounts for different induction
Frontiers in Psychology | www.frontiersin.org 2July 2018 | Volume 9 | Article 1028
Schmidt and Berkemeyer The Altered States Database
TABLE 1 | Questionnaires and their factor/scale-structure from which data is included.
Questionnaire Versions Scales/Factors Original publication Psychometric properties
Altered States of Consciousness
Rating Scale
APZ (1) Oceanic Boundlessness, (2) Dread of Ego
Dissolution, (3) Visionary Restructuralization Dittrich, 1975, 1985 Dittrich, 1985
5D-ASC (1) Oceanic Boundlessness, (2) Dread of Ego
Dissolution, (3) Visionary Restructuralization, (4)
Auditory Alterations, (5) Vigilance Reduction
Bodmer et al., 1994; Dittrich
et al., 2006
Dittrich et al., 2010
11D-ASC (1) Experience of Unity, (2) Spiritual Experience,
(3) Blissful State, (4) Insightfulness, (5)
Disembodiment, (6) Impaired Control and
Cognition, (7) Anxiety, (8) Complex Imagery, (9)
Elementary Imagery, (10) Audio-Visual
Synesthesia, (11) Changed Meaning of
Percepts
Studerus et al., 2010 Studerus et al., 2010
Phenomenology of Consciousness
Inventory
PCI (1) Positive Affect, (a.) Joy, (b.) Sexual
Excitement, (c.) Love, (2) Negative Affect (a.)
Anger, (b.) Sadness, (c.) Fear, (3) Altered
Experience, (a.) Altered Body Image, (b.)
Altered Time Sense, (c.) Altered Perception, (d.)
Altered Meaning, (4) Visual Imagery, (a.)
Amount, (b.) Vividness, (5) Attention, (a.)
Direction, (b.) Absorption, (6) Self Awareness,
(7) Altered State of Awareness, (8) Internal
Dialogue, (9) Rationality, (10) Volitional Control,
(11) Memory, (12) Arousal
Pekala, 1991 Pekala, 1991, 1995;
German version: Rux, 2002
Hallucinogen Rating Scale HRS (1) Somaesthesia (2) Affect (3) Perception (4)
Cognition (5) Volition (6) Intensity Strassman et al., 1994 Strassman et al., 1994; Riba
et al., 2001; Bouso et al.,
2016
Mystical Experience Questionnaire MEQ30 (1) Mystical, (2) Positive Mood (3)
Transcendence of time and space (4) Ineffability Pahnke, 1963, 1966;
MacLean et al., 2012
MacLean et al., 2012;
Barrett et al., 2015; Spanish
version:Bouso et al., 2016;
Portugese version:
Schenberg et al., 2017
Each questionnaire has a specific structure of factors/scales (and subscales in the case of the PCI), for which research articles typically report group summary data, i.e., mean ±
variability. Data on the questionnaires psychometric properties, as well as validation and reliability measures can be obtained from the provided references. The literature research to
identify relevant research data was primarily based on forward-citations of the questionnaires original reports and reports on methodological refinements and translations.
methods linked to possible modes of administration (e.g.,
“i.v.,” “capsule(oral)” etc.) and dosage (e.g., “0.5 mg”). The
database has been designed to represent questionnaire data
mainly in the format of group mean ±standard deviation.
The data model is also prepared to capture raw data of
individual participants on the item-level, which unfortunately is
by now not made available by research groups. An individual
dataset (experiment) was defined as any unique combination of
experimental conditions and questionnaire to capture that one
research article can contain multiple datasets (e.g., applications
of different induction methods and/or dosages result in different
datasets). The model further contains the following data
attributes: PUBMED_ID, DOI, language the questionnaire was
applied in, sample size, T/F-identifier if the dataset stems from
a control condition (e.g., “Placebo administration”), the time the
questionnaire was applied after the application of the induction
method.
Limitations and Updates
The database is supposedly complete for the data published
until the end of 2017 but limited by human error within the
literature screening. The scope of the database is limited by the
available data, is, however, assumed to stimulate the collection
of new data for missing combinations of induction methods,
dosages, and questionnaires. Depending on future publications
and developments in the quantification of ASCs, the database
will be regularly updated with (1) newly published datasets (2)
data from additional and newly developed questionnaires, as
soon as questionnaires reach a substantial prevalence in the
literature to allow study-overarching comparisons. Ultimately,
the ASDB shall be supplemented with data on physiological
measures such as neuroimaging data, to allow meta-analyses
on the relationships between phenomenology and physiological
processes [i.e., as suggested in the study of neurophenomenology
(Varela, 1996)].
Frontiers in Psychology | www.frontiersin.org 3July 2018 | Volume 9 | Article 1028
Schmidt and Berkemeyer The Altered States Database
Updates will be made available (with date and version
number) in the same format as the original publication (see Data
Records) assuring full open access to the data and transparency
about data inclusion/exclusion allowing to correct potential
human errors. Updates will be performed by the database
administrators and not by users to assure data quality.
DATA RECORDS
The database can be accessed in two ways: (1) Database queries
can be posed and results visualized via a web interface on
www.asdb.info. Output graphs have mouse-over functionality
to display the original data and provide full access without
any database skills. (2) Data in table-format containing all
original data can be obtained from the Open Science Framework
repository Schmidt (2018).
TECHNICAL VALIDATION
Accuracy
All data points have been extracted by humans and have
been double-checked for accuracy by a second person.
Inclusion/Exclusion as well as any adjustments and
normalization of data has been documented and can be
obtained together with the overall dataset.
Completeness
The given search procedure makes it likely to contain all
relevant data. However, a failure to cite the original references
of the questionnaire can lead to missing articles. If articles
were overseen, please contact the corresponding author, and
suitable data will be included in the database with the next
update.
The database currently (01/2018) contains data from
N=6,861 reports of ASC experiences which were reported in
N=315 datasets (defined as a unique combination of induction
method/experimental conditions and questionnaire) that were
extracted as 2,168 total data points (constituted of mean and
standard deviation, if available). Data were extracted from
the following amounts of articles per questionnaire: N=11
APZ; N=43 5D-ASC; N=15 11D-ASC; N=3 PCI; N=32
HRS; N=3 MEQ30; and comprise N=52 different induction
methods.
USAGE NOTES
Meta-Analyses should consider that information on
dependencies of the datasets (e.g., information on repeated
measures designs) are currently not provided in the database.
AUTHOR CONTRIBUTIONS
TS wrote the manuscript and HB substantially contributed to the
manuscript. TS initiated and superintended the ASDB project.
TS and HB designed the database. HB implemented the database
structure and data upload. TS superintended the data extraction,
performed quality control, and is responsible for the long-term
maintenance.
ACKNOWLEDGMENTS
We would like to thank Eelke de Vries, Artur Czeszumski,
Philipp Kuhnke, Ahmad Dawud, Auss Abbood, Lorenzo
Semeia, Natalia Esther Bradwayn, Mohammadreza Baghery,
Mina Bakharzi, Ashima Keshava, Kristina Baumgart, Lesley-
Ann Mathis, Anastasia Mukhina, Alexa-Nicole Sibly, Paola
Suarez, Felix Blind, Öykü Bulca for contributions to literature
research, data extraction, and double-checking of data; Renato
Garita Figueiredo, Artur Czeszumski for contributions to the
database design; Hristofor Lukanov for contributions to the
website visualization; Axel Kohler for contributions to project
management.
TS was supported by the Fellowprogram Open Knowledge by
the Wikimedia foundation.
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Conflict of Interest Statement: The authors declare that the research was
conducted in the absence of any commercial or financial relationships that could
be construed as a potential conflict of interest.
Copyright © 2018 Schmidt and Berkemeyer. This is an open-access article distributed
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author(s) and the copyright owner(s) are credited and that the original publication
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distribution or reproduction is permitted which does not comply with these terms.
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... Dittrich proposed that ASCs share common features of multidimensional alterations referred to as etiology independence, meaning that alterations are shared independent of the mechanism of induction (Dittrich, 1998). To test this hypothesis, scales were created and revised most notably resulting in the creation of the 5-Dimensional Altered States of Consciousness (5D-ASC) Rating Scale, the most popular psychometric tool for measuring subjective experience in ASCs with its associated 11 factor scoring scheme (Schmidt & Berkemeyer, 2018;Studerus et al., 2010). It should be noted that the Etiology-Independent Structures of ASCs was conceptualized to understand a more complete phenomenological profile of ASCs, and not just a specific dimension of the experience as is done with the Categories of a Typology of Mysticism (Dittrich, 1975;Pahnke, 1963). ...
... simple hallucinations); (10) the Audio-visual Synesthesia factor representing the interaction and influence of different sensory modalities such as noise influencing visual experience and sound changing colors and shapes; (11) and the Changed Meaning of Percepts factor representing enhanced meaning and stronger emotional reactions to everyday objects. While not explicitly named in the Studerus et al. paper, many researchers have opted for calling this scoring scheme the 11-ASC (Schmidt & Berkemeyer, 2018) The Etiology-Independent Structures of ASCs is a highly important framework for modern ASC research, as one of its questionnaires, namely the 5D-ASC and its associated 11-ASC scoring scheme, are the most prevalent questionnaires in studies examining altered experiences across various states of consciousness including those induced by drugs and/or perceptual deprivation (Hirschfeld et al., 2023;Hirschfeld & Schmidt, 2021;Prugger et al., 2022;Schmidt & Berkemeyer, 2018). This framework provides a structured way of understanding and quantifying the subjective experiences of ASCs, facilitating comparison across studies and enhancing our understanding of the underlying dimensions of altered consciousness. ...
... simple hallucinations); (10) the Audio-visual Synesthesia factor representing the interaction and influence of different sensory modalities such as noise influencing visual experience and sound changing colors and shapes; (11) and the Changed Meaning of Percepts factor representing enhanced meaning and stronger emotional reactions to everyday objects. While not explicitly named in the Studerus et al. paper, many researchers have opted for calling this scoring scheme the 11-ASC (Schmidt & Berkemeyer, 2018) The Etiology-Independent Structures of ASCs is a highly important framework for modern ASC research, as one of its questionnaires, namely the 5D-ASC and its associated 11-ASC scoring scheme, are the most prevalent questionnaires in studies examining altered experiences across various states of consciousness including those induced by drugs and/or perceptual deprivation (Hirschfeld et al., 2023;Hirschfeld & Schmidt, 2021;Prugger et al., 2022;Schmidt & Berkemeyer, 2018). This framework provides a structured way of understanding and quantifying the subjective experiences of ASCs, facilitating comparison across studies and enhancing our understanding of the underlying dimensions of altered consciousness. ...
Classification Schemes of Altered States of Consciousness
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  • Sep 2024
In recent years, there has been a renewed interest in the conceptual and empirical study of altered states of consciousness (ASCs) induced pharmacologically or otherwise, driven by their potential clinical applications. To draw attention to the rich history of research in this domain, we review prominent classification schemes that have been proposed to introduce systematicity in the scientific study of ASCs. The reviewed ASC classification schemes fall into three groups according to the criteria they use for categorization: (1) based on the nature, variety, and intensity of subjective experiences (state-based), including conceptual descriptions and psychometric assessments, (2) based on the technique of induction (method-based), and (3) descriptions of neurophysiological mechanisms of ASCs (neuro/physio-based). By comparing and extending existing classification schemes, we can enhance efforts to identify neural correlates of consciousness, particularly when examining mechanisms of ASC induction and the resulting subjective experience. Furthermore, an overview of what defining ASC characteristics different authors have proposed can inform future research in the conceptualization and quantification of ASC subjective effects, including the identification of those that might be relevant in clinical research. This review concludes by clustering the concepts from the state-based schemes, which are suggested for classifying ASC experiences. The resulting clusters can inspire future approaches to formulate and quantify the core phenomenology of ASC experiences to assist in basic and clinical research.
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... At the end of each trial (as in Aspell et al., 2009;Park et al., 2016), we gauged participants' mislocation of touch ( "I felt as if the touch was located where I saw the stroking"), self-identification ( "I felt as if the body I saw was my body"), and a control question ( "I felt as if I had more than three bodies"), using a 7-point Likert scale. 13 Finally, participants took off the VR headset and earplugs and were given a tablet on which to fill the 5-Dimensional Altered States of Consciousness Rating Scale questionnaire (5D-ASC, Schmidt & Berkemeyer, 2018). After a short break, the other condition was performed following a similar procedure. ...
... Thus, integrating a 1PP to 3PP shift in perspective into meditation was associated with OBE-like sensations during meditation practice, comparable to such sensations reported in different experimental setups manipulating visuo-tactile in healthy individuals (Ehrsson, 2007;Ionta et al., 2011;Pfeiffer et al., 2013Pfeiffer et al., , 2016 or visuo-vestibular signals (Wu et al., 2024). They also correspond to disembodiment scores in the 5D-ASC (Schmidt & Berkemeyer, 2018), though less intense than reported after intake of psychedelic substances (i.e., 29 lysergic acid diethylamide; Kraehenmann et al., 2017). The present OBE-sensations were also weaker than those reported in OBEs of neurological patients (Blanke et al., 2002(Blanke et al., , 2004(Blanke et al., , 2005Hiromitsu et al., 2020) or spontaneous OBEs in healthy participants (Braithwaite et al., 2011;Milne et al., 2019). ...
Meditation in the third-person perspective modulates minimal self and heartbeat-evoked potentials
Preprint
  • Oct 2024
Experienced meditation practitioners often report altered states of their sense of self, including decentering and distancing the self from the body and current concerns. Altered states of the sense of self, such as disembodiment and distancing of the self from the body, have also been induced experimentally using virtual reality (VR) and linked neurally to heartbeat evoked potentials (HEPs). Whereas many studies investigated the related neural correlates of such decentering during meditation, none experimentally modulated the sense of self during meditation practice using VR nor determined the potentially associated behavioral changes of the sense of self. Here we determined HEPs and behavioral measures in 23 participants who performed a guided meditation practice in VR, either from a third-person (3PP) or first-person perspective (1PP) to modulate the sense of self. In the 3PP versus 1PP meditation condition, we report stronger sensations of detachment and disconnection, reduced salience of the perceived body boundary, and reduced self-identification with the body. HEP analysis revealed differential neural responses between conditions, characterized by a more negative HEP amplitude in the 3PP condition, associated with activation of the posterior cingulate cortex and medial prefrontal cortex. Leveraging a new VR-supported meditation platform and methods, these data link the sense of self in meditation practice to the neuroscience of the bodily self, based on subjective, behavioral, and neural measures.
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... (https://osf.io/8mbru/; Schmidt and Berkemeyer 2018;Prugger et al. 2022). Beyond these quantitative sources, qualitative methods have been the basis for understanding subjective experiences within psychology, psychiatry, and psychedelic research. ...
Phenomenology of Psychedelic Experiences and Psychedelic-Associated Distressing Effects: Quantifying Subjective Experiences
Chapter
  • Dec 2024
The range of phenomena that can be induced by psychedelic substances is broad and variable, including effects on perception, cognition, and emotion. The umbrella term “psychedelic phenomenology” is used to refer to a combination of altered experiential features, such as hallucinations or ego dissolution, which together constitute a psychedelic experience. However, there is no consensus on the set of alterations of consciousness that qualifies an altered state to be a “psychedelic state.” In this chapter we summarize the most commonly discussed changes in subjective experiences which could be seen as “core features” of psychedelic experiences. While acknowledging the rich history of pioneering phenomenological work of the last century, this chapter focuses on more recent developments in the quantitative work on the assessment of these phenomena. We also address the under-researched phenomenology of distressing effects, often referred to as “challenging experiences” or “bad trips,” and point to their importance in understanding the therapeutic potential and risks associated with psychedelic phenomenology. Historically, one can find many links between psychedelic phenomenology and the phenomenology of psychopathology. We stress the importance to refine the assessment and description also of distressing effects, to identify factors that promote acute experiences which are beneficial and limit those which can have potentially harmful long-term effects.
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... The flicker-induced effects are mainly constituted of elementary visual hallucinations, referring to the perception of geometric patterns and colors devoid of semantic content (Amaya, Behrens, Schwartzman, Hewitt, & Schmidt, 2023;Bartossek, Kemmerer, & Schmidt, 2021). These elementary phenomena are also frequently reported during psychedelic experiences (Prugger, Derdiyok, Dinkelacker, Costines, & Schmidt, 2022;Schmidt & Berkemeyer, 2018), for those with Charles Bonnet syndrome (Jan & del Castillo, 2012), and for some patients with psychosis (van Ommen, van Laar, Cornelissen, & Bruggeman, 2019). Therefore, utilizing FLS allows the assessment of specific neural effects occurring during visual hallucinations that are also experienced in other pathologies and pharmacologically induced states. ...
Thalamocortical interactions reflecting the intensity of flicker light–induced visual hallucinatory phenomena
Article
Full-text available
  • Oct 2024
Aberrant thalamocortical connectivity occurs together with visual hallucinations in various pathologies and drug-induced states, highlighting the need to better understand how thalamocortical interactions may contribute to hallucinatory phenomena. Flicker light stimulation (FLS) at 10 Hz reliably and selectively induces transient visual hallucinations in healthy participants. Arrhythmic flicker elicits fewer hallucinatory effects while delivering equal amounts of visual stimulation, together facilitating a well-controlled experimental setup to investigate the neural correlates of visual hallucinations driven by flicker rhythmicity. Using rhythmic and arrhythmic FLS during fMRI scanning, we found that rhythmic FLS elicited stronger activation in higher order visual cortices compared with arrhythmic control. Consistently, we found that rhythmic flicker selectively increased connectivity between ventroanterior thalamic nuclei and higher order visual cortices, which was also positively associated with the subjective intensity of visual hallucinatory effects. As these thalamic and cortical areas do not receive primary visual inputs, it suggests that the thalamocortical connectivity changes relate to a higher order function of the thalamus, such as in the coordination of cortical activity. In sum, we present novel evidence for the role of specific thalamocortical interactions with ventroanterior nuclei within visual hallucinatory experiences. Importantly, this can inform future clinical research into the mechanistic underpinnings of pathologic hallucinations.
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... Mystical-type experiences, ego dissolution, and other psychedelic drug effects are usually measured retrospectively, after a return to normal consciousness (Schmid et al., 2021;Schmidt and Berkemeyer, 2018). However, it is also feasible to obtain measures of psychedelic drug effects in real time using relatively simple measures in the form of visual analog scales (Holze et al., 2022b) or verbal Likert scales (Vogt et al., 2023). ...
Naturalistic psychedelic therapy: The role of relaxation and subjective drug effects in antidepressant response
Article
Full-text available
  • Sep 2024
Background Psychedelic-assisted therapy (PAT) is permitted in Switzerland under its limited medical use program. Data from patients in this program represent a unique opportunity to analyze the real-world practice of PAT. Aims This study compared the subjective effects of lysergic acid diethylamide (LSD) and psilocybin between patients undergoing PAT and healthy volunteers. For the patients, it also investigated the relationship between antidepressant effects and six measures of acute drug effects. Methods We compared data on acute psychedelic drug effects between 28 PAT patients with data from 28 healthy participants who participated in a randomized, double-blind crossover trial. All participants received varying doses of psilocybin and LSD. Subjective effects were assessed on an hourly basis during the acute drug effects, and the Mystical Experience Questionnaire (MEQ) was completed retrospectively. For patients, depressive symptoms were assessed using the Montgomery-Åsberg Depression Rating Scale (MADRS). Results Ratings of overall drug effect and mystical experience were similar across groups. Compared with healthy controls, patients reported lower ratings of ego dissolution. Patients showed a significant decrease in MADRS scores, and the greatest predictor of antidepressant outcome was relaxation during the PAT session. We did not observe a relationship between mystical-type experiences and antidepressant effects. Most patients experienced mild adverse effects which resolved within 48 h. Conclusion PAT reduced depressive symptoms in this heterogeneous patient group. Patients may experience more challenging psychedelic effects and reduced ego dissolution. Hourly assessment of drug effects may predict clinical outcomes better than retrospectively assessed mystical experiences, and the impact of relaxation during PAT should be investigated further.
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... Measurements were repeated on Day 8 to assess recovery of baseline memory function following elimination of psilocybin +/− midazolam. The Day 8 tasks included both items from Day 1 along with new distractors drawn from thematically similar scales not used on dosing day [50]. ...
Co-administration of midazolam and psilocybin: differential effects on subjective quality versus memory of the psychedelic experience
Article
Full-text available
  • Sep 2024
Aspects of the acute experience induced by the serotonergic psychedelic psilocybin predict symptomatic relief in multiple psychiatric disorders and improved well-being in healthy participants, but whether these therapeutic effects are immediate or are based on memories of the experience is unclear. To examine this, we co-administered psilocybin (25 mg) with the amnestic benzodiazepine midazolam in 8 healthy participants and assayed the subjective quality of, and memory for, the dosing-day experience. We identified a midazolam dose that allowed a conscious psychedelic experience to occur while partially impairing memory for the experience. Furthermore, midazolam dose and memory impairment tended to associate inversely with salience, insight, and well-being induced by psilocybin. These data suggest a role for memory in therapeutically relevant behavioral effects occasioned by psilocybin. Because midazolam blocks memory by blocking cortical neural plasticity, it may also be useful for evaluating the contribution of the pro-neuroplastic properties of psychedelics to their therapeutic activity.
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... ASC can be induced by the application of pharmacological methods based on psychoactive substances, or by nonpharmacological methods, such as sensory deprivation, sensory overload, hypnosis, breathing techniques, or meditation practices [26][27][28]. Several psychometric scales have been developed to quantify the different aspects of ASCs [29][30][31][32]. There is a dearth of research investigating the effects of ASCs on physical and mental health, but existing data, mostly of a cross-sectional or qualitative nature, suggests that their effects on mental health and wellbeing depend heavily on the nature of the ASC, the context of the event, how much the ASC is expected, how it is dealt with, any external support available, and the meaning that the ASC has to the individual experiencing it [33][34][35]. ...
Altered states of consciousness caused by a mindfulness-based programme up to a year later: Results from a randomised controlled trial
Article
Full-text available
Background Mindfulness-based programmes (MBPs) have shown beneficial effects on mental health. There is emerging evidence that MBPs may also be associated with marked deviations in the subjective experience of waking consciousness. We aimed to explore whether MBPs can have a causal role in different types of such states. Methods We conducted a pragmatic randomised controlled trial (ACTRN12615001160527). University of Cambridge students without severe mental illness were randomised to an 8-week MBP plus mental health support as usual (SAU), or to SAU alone. We adapted the Altered States of Consciousness Rating Scale (OAV, 0–100-point range) to assess spontaneous experiences in daily life, and included it as a post-hoc secondary outcome at the end of the one-year follow-up questionnaire. Two-part model analyses compared trial arms, and estimated dose-response effects of formal (meditation) and informal (daily activities) mindfulness practice during the year. Sensitivity analyses correcting for multiple comparisons were conducted. Results We randomised 670 participants; 205 (33%) completed the OAV. In comparison with SAU, MBP participants experienced unity more frequently and intensively (two-part marginal effect (ME) = 6.26 OAV scale points, 95% confidence interval (CI) = 2.24, 10.27, p = 0.006, Cohen’s d = 0.33) and disembodiment more frequently (ME = 4.84, 95% CI = 0.86, 8.83, p = 0.019, Cohen’s d = 0.26). Formal practice predicted spiritual, blissful and unity experiences, insightfulness, disembodiment, and changed meanings. Informal practice predicted unity and blissful experiences. Trial arm comparisons and informal practice effects lost significance after corrections for multiple comparisons, but formal practice dose-response effects remained significant. Conclusions Results provide a novel suggestion of causal links between mindfulness practice and specific altered states of consciousness. To optimise their impact, practitioners and teachers need to anticipate and handle them appropriately. Future studies need to confirm findings and assess mechanisms and clinical implications.
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... Overall, and as alluded to in our introduction, what many call Altered-States of Consciousness (ASCs) comes closest to the domain we are trying to define here. The notion does convey the intuitive unity of the experiential and practical domain of concern, and recent initiatives such as the Altered-States Database (Schmidt and Berkemeyer, 2018;Prugger et al., 2022) align with our core hypothesis -namely, that the dedicated study of this domain across induction methods and contexts of occurrence is possible and desirable. ...
Documenting and defining emergent phenomenology: theoretical foundations for an extensive research strategy
Article
Full-text available
  • Jul 2024
Meditation, psychedelics, and other similar practices or induction methods that can modulate conscious experience, are becoming increasingly popular in clinical and non-clinical settings. The phenomenology associated with such practices or modalities is vast. Many similar effects and experiences are also reported to occur spontaneously. We argue that this experiential range is still not fully described or understood in the contemporary literature, and that there is an ethical mandate to research it more extensively, starting with comprehensive documentation and definition. We review 50 recent clinical or scientific publications to assess the range of phenomena, experiences, effects, after-effects, and impacts associated with a broad variety of psychoactive compounds, meditative practices, and other modalities or events. This results in a large inventory synthesizing the reports of over 30,000 individual subjects. We then critically discuss various terms and concepts that have been used in recent literature to designate all or parts of the range this inventory covers. We make the case that specialized terminologies are needed to ground the nascent research field that is forming around this experiential domain. As a step in this direction, we propose the notion of “emergence” and some of its derivatives, such as “emergent phenomenology,” as possibly foundational candidates.
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... The ICI (Cavanna et al., 2008), as a method intended to place patients' experiences during epileptic seizures on the two dimensions of the bidimensional model, has already been reviewed in section 3.1. However, there is also a group of questionnaires assessing altered states of consciousness that have seen extensive use in research (Schmidt and Berkemeyer, 2018), some of which describe altered states using dimensions. ...
What does it mean for consciousness to be multidimensional? A narrative review
Article
Full-text available
  • Jun 2024
A recent development in the psychological and neuroscientific study of consciousness has been the tendency to conceptualize consciousness as a multidimensional phenomenon. This narrative review elucidates the notion of dimensionality of consciousness and outlines the key concepts and disagreements on this topic through the viewpoints of several theoretical proposals. The reviewed literature is critically evaluated, and the main issues to be resolved by future theoretical and empirical work are identified: the problems of dimension selection and dimension aggregation, as well as some ethical considerations. This narrative review is seemingly the first to comprehensively overview this specific aspect of consciousness science.
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Translation and cultural adaptation of the States of Consciousness Questionnaire (SOCQ) and statistical validation of the Mystical Experience Questionnaire (MEQ30) in Brazilian Portuguese
Article
Full-text available
  • Jan 2017
Background The States of Consciousness Questionnaire (SOCQ) was developed to assess the occurrence features of the change in consciousness induced by psilocybin, and includes the Mystical Experience Questionnaire (MEQ), developed to assess the ocurrence of mystical experiences in altered states of consciousness. Objective To translate the SOCQ to Brazilian Portuguese and validate the 30-item MEQ. Methods The SOCQ was translated to Brazilian Portuguese and backtranslated into English. The two English versions were compared and differences corrected, resulting in a Brazilian translation. Using an internet-survey, 1504 Portuguese-speaking subjects answered the translated version of the SOCQ. The 4-factor version of MEQ30 was analyzed using confirmatory factor analysis and reliability analysis. Results A Brazilian Portuguese version of the SOCQ was made available. Goodness-of-fit indexes indicated that data met the factorial structure proposed for the English MEQ30. Factors presented excellent to acceptable reliability according to Cronbach’s alpha: mystical (0.95); positive mood (0.71); transcendence of time/space (0.83); and ineffability (0.81). Discussion The Brazilian Portuguese version of the MEQ30 is validated and it fits in the factorial structure performed on the original English version. The SOCQ is also available to the Brazilian Portuguese speaking population, allowing studies in different languages to be conducted and compared systematically.
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Neural correlates of the LSD experience revealed by multimodal neuroimaging
Article
Full-text available
  • Apr 2016
Significance Lysergic acid diethylamide (LSD), the prototypical “psychedelic,” may be unique among psychoactive substances. In the decades that followed its discovery, the magnitude of its effect on science, the arts, and society was unprecedented. LSD produces profound, sometimes life-changing experiences in microgram doses, making it a particularly powerful scientific tool. Here we sought to examine its effects on brain activity, using cutting-edge and complementary neuroimaging techniques in the first modern neuroimaging study of LSD. Results revealed marked changes in brain blood flow, electrical activity, and network communication patterns that correlated strongly with the drug’s hallucinatory and other consciousness-altering properties. These results have implications for the neurobiology of consciousness and for potential applications of LSD in psychological research.
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Validation of the revised Mystical Experience Questionnaire in experimental sessions with psilocybin
Article
Full-text available
  • Oct 2015
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.
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Acute Effects of Lysergic Acid Diethylamide in Healthy Subjects
Article
Full-text available
  • Nov 2014
  • BIOL PSYCHIAT
After no research in humans for >40 years, there is renewed interest in using lysergic acid diethylamide (LSD) in clinical psychiatric research and practice. There are no modern studies on the subjective and autonomic effects of LSD, and its endocrine effects are unknown. In animals, LSD disrupts prepulse inhibition (PPI) of the acoustic startle response, and patients with schizophrenia exhibit similar impairments in PPI. However, no data are available on the effects of LSD on PPI in humans. In a double-blind, randomized, placebo-controlled, crossover study, LSD (200 μg) and placebo were administered to 16 healthy subjects (8 women, 8 men). Outcome measures included psychometric scales; investigator ratings; PPI of the acoustic startle response; and autonomic, endocrine, and adverse effects. Administration of LSD to healthy subjects produced pronounced alterations in waking consciousness that lasted 12 hours. The predominant effects induced by LSD included visual hallucinations, audiovisual synesthesia, and positively experienced derealization and depersonalization phenomena. Subjective well-being, happiness, closeness to others, openness, and trust were increased by LSD. Compared with placebo, LSD decreased PPI. LSD significantly increased blood pressure, heart rate, body temperature, pupil size, plasma cortisol, prolactin, oxytocin, and epinephrine. Adverse effects produced by LSD completely subsided within 72 hours. No severe acute adverse effects were observed. In addition to marked hallucinogenic effects, LSD exerts methylenedioxymethamphetamine-like empathogenic mood effects that may be useful in psychotherapy. LSD altered sensorimotor gating in a human model of psychosis, supporting the use of LSD in translational psychiatric research. In a controlled clinical setting, LSD can be used safely, but it produces significant sympathomimetic stimulation. Copyright © 2014 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
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Broadband Cortical Desynchronization Underlies the Human Psychedelic State
Article
Full-text available
  • Sep 2013
  • J NEUROSCI
Psychedelic drugs produce profound changes in consciousness, but the underlying neurobiological mechanisms for this remain unclear. Spontaneous and induced oscillatory activity was recorded in healthy human participants with magnetoencephalography after intravenous infusion of psilocybin-prodrug of the nonselective serotonin 2A receptor agonist and classic psychedelic psilocin. Psilocybin reduced spontaneous cortical oscillatory power from 1 to 50 Hz in posterior association cortices, and from 8 to 100 Hz in frontal association cortices. Large decreases in oscillatory power were seen in areas of the default-mode network. Independent component analysis was used to identify a number of resting-state networks, and activity in these was similarly decreased after psilocybin. Psilocybin had no effect on low-level visually induced and motor-induced gamma-band oscillations, suggesting that some basic elements of oscillatory brain activity are relatively preserved during the psychedelic experience. Dynamic causal modeling revealed that posterior cingulate cortex desynchronization can be explained by increased excitability of deep-layer pyramidal neurons, which are known to be rich in 5-HT2A receptors. These findings suggest that the subjective effects of psychedelics result from a desynchronization of ongoing oscillatory rhythms in the cortex, likely triggered by 5-HT2A receptor-mediated excitation of deep pyramidal cells.
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Empirische Untersuchung veränderter Bewusstseinszustände
Chapter
  • Jan 2018
Ein Ziel der neurowissenschaftlichen Bewusstseinsforschung besteht in der Charakterisierung neuronaler Mechanismen, die bestimmte Funktionen des Bewusstseins ermöglichen. In der empirischen Forschung kann die experimentelle Induktion einer reversiblen Bewusstseinsveränderung genutzt werden, um gleichzeitig auftretende Veränderungen in neuronalen Prozessen zu erfassen. Dadurch sollen Rückschlüsse auf neuronale Korrelate des subjektiven Erlebens ermöglicht werden. Da induzierte Zustände zwischen Studien und Probanden stark variieren, ist eine präzise Quantifizierung des subjektiven Erlebens notwendig, um studienübergreifende Vergleichbarkeit herzustellen. In dem vorliegenden Kapitel werden nach einer groben Einteilung experimentell nutzbarer Bewusstseinsveränderungen die besonderen Herausforderungen der Quantifizierung von subjektivem Erleben diskutiert. Ein Überblick über die derzeit verfügbaren psychometrischen Instrumente (Fragebögen) sowie über die physiologisch relevanten Variablen soll zukünftigen Studien bei der Auswahl von Messinstrumenten helfen, um die Vergleichbarkeit von Forschungsergebnissen zu fördern und den Einfluss möglicher Störvariablen zu minimieren.
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Empirische Untersuchung veränderter Bewusstseinszustände
Chapter
  • Oct 2016
Ein Ziel der neurowissenschaftlichen Bewusstseinsforschung besteht in der Charakterisierung neuronaler Mechanismen, die bestimmte Funktionen des Bewusstseins ermöglichen. In der empirischen Forschung kann die experimentelle Induktion einer reversiblen Bewusstseinsveränderung genutzt werden, um gleichzeitig auftretende Veränderungen in neuronalen Prozessen zu erfassen. Dadurch sollen Rückschlüsse auf neuronale Korrelate des subjektiven Erlebens ermöglicht werden. Da induzierte Zustände zwischen Studien und Probanden stark variieren, ist eine präzise Quantifizierung des subjektiven Erlebens notwendig, um studienübergreifende Vergleichbarkeit herzustellen. In dem vorliegenden Kapitel werden nach einer groben Einteilung experimentell nutzbarer Bewusstseinsveränderungen die besonderen Herausforderungen der Quantifizierung von subjektivem Erleben diskutiert. Ein Überblick über die derzeit verfügbaren psychometrischen Instrumente (Fragebögen) sowie über die physiologisch relevanten Variablen soll zukünftigen Studien bei der Auswahl von Messinstrumenten helfen, um die Vergleichbarkeit von Forschungsergebnissen zu fördern und den Einfluss möglicher Störvariablen zu minimieren.
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Measuring the subjective: revisiting the psychometric properties of three rating scales that assess the acute effects of hallucinogens
Article
  • Jul 2016
  • HUM PSYCHOPHARM CLIN
Objective: In the present study we explored the psychometric properties of three widely used questionnaires to assess the subjective effects of hallucinogens: the Hallucinogen Rating Scale (HRS), the Mystical Experience Questionnaire (MEQ), and the Addiction Research Center Inventory (ARCI). Methods: These three questionnaires were administered to a sample of 158 subjects (100 men) after taking ayahuasca, a hallucinogen whose main active component is N,N-dimethyltryptamine (DMT). A confirmatory factorial study was conducted to check the adjustment of previous data obtained via theoretical proposals. When this was not possible, we used an exploratory factor analysis without restrictions, based on tetrachoric and polychoric matrices and correlations. Results: Our results sparsely match the theoretical proposals of the authors, perhaps because previous studies have not always employed psychometric methods appropriate to the data obtained. However, these data should be considered preliminary, pending larger samples to confirm or reject the proposed structures obtained. Conclusions: It is crucial that instruments of sufficiently precise measurement are utilized to make sense of the information obtained in the study of the subjective effects of psychedelic drugs. Copyright © 2016 John Wiley & Sons, Ltd.
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Psychedelic, Psychoactive, and Addictive Drugs and States of Consciousness
Article
  • Jan 2010
This chapter examines the states of consciousness induced by hallucinogens or psychedelic drugs in the framework of a general model of altered states of consciousness (ASCs). According to the general model of ASCs, the content of a state of consciousness is a function of the internal set and external setting, regardless of the catalyst or trigger, which might be a drug, hypnotic induction, shock, rhythmic sounds, music, and so forth. Altered states of consciousness, whether induced by drugs or other means, differ energetically on the dimensions of (a) arousal versus sedation, (b) pleasure versus pain, and (c) expansion versus contraction. It is argued that the classical hallucinogenic or psychedelic drugs are consciousness-expanding and therefore opposite in effect to drugs such as the opiates, alcohol, cocaine, and amphetamines, all of which can lead to addicted, fixated, contracted states of consciousness. Drugs, such as the stimulants and depressants in moderate dosages, which affect primarily the dimensions of arousal andpleasure-pain, without significant expansion of consciousness, are referred to as psychoactive (or "mood regulating"). The implications for applications in psychotherapy are also discussed.
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