Dimensions of consciousness and the psychedelic state

This theoretical review (2018) critically analyzes whether psychedelic-induced experiences constitute a “higher state of consciousness” and argues that a unidimensional mode of classification is not appropriate, given that there are multiple ways in which altered states of consciousness may be ‘higher’ or ‘lower’ from one another across multiple dimensions.

Abstract

“Introduction: It has often been suggested in the popular and academic literature that the psychedelic state qualifies as a higher state of consciousness relative to the state of normal waking awareness. This article subjects this proposal to critical scrutiny, focusing on the question of what it would mean for a state of consciousness to be ‘higher’.

Methods: We begin by considering the contrast between conscious contents and conscious global states. We then review the changes in conscious global state associated with psychedelic drug use, focusing on the effects of two serotonergic hallucinogens: psilocybin and lysergic acid diethylamide. Limiting our review to findings obtained from lab-based experiments and reported in peer-reviewed journals, we prioritize the more common and reliably induced effects obtained through subjective questionnaires and psychophysical measures.

Results: The findings are grouped into three broad categories (sensory perception, cognitive function, and experiences of unity) and demonstrate that although certain aspects of consciousness are improved or enhanced in the psychedelic state, many of the functional capacities that are associated with consciousness are seriously compromised.

Discussion: Psychedelic-induced states of consciousness are indeed remarkable in many ways, but it is inappropriate to regard them as ‘higher’ states of consciousness. The fact that psychedelics affect different aspects of consciousness in fundamentally different ways provides evidence against the unidimensional (or ‘level-based’) view of consciousness, and instead provides strong support for a multidimensional conception of conscious states. The final section of the article considers the implications of this analysis for two prominent theories of consciousness: the Global Workspace Theory and Integrated Information Theory.”

Authors: Tim Bayne & Olivia Carter

Summary

It has often been suggested that the psychedelic state qualifies as a higher state of consciousness than normal waking awareness. This article reviews the effects of two serotonergic hallucinogens on conscious global state and demonstrates that many functional capacities are seriously compromised.

Introduction

The science of consciousness distinguishes between the ‘contents of consciousness’ and the ‘states of consciousness’, and uses this distinction to measure consciousness and investigate consciousness in non-human animals and infants.

Although many unresolved questions remain about the contents of consciousness, the notion of a conscious state is relatively well-understood.

In ordinary waking awareness, a wide variety of contents can enter consciousness, and a wide variety of cognitive and behavioural capacities can be exercised. In other conscious states, however, both the range of conscious contents and the range of cognitive and behavioural capacities may be curtailed.

In the literature, conscious states are usually understood in terms of distinct ‘levels of consciousness’. However, this terminology assumes that conscious states can be ordered along a single dimension, which is open to various kinds of challenges. We will argue that the relationship between conscious states should be construed in multidimensional terms, and that the psychedelic state is neither ‘higher’ nor ‘lower’ than ordinary waking awareness.

Charting the Psychedelic State of Consciousness

We will focus on two of the most commonly used serotonergic hallucinogens, LSD and psilocybin, and use ‘psychedelic state’ as a general term to refer to the paradigmatic states of consciousness associated with the consumption of these substances.

We will focus on reported subjective changes to an individual’s conscious experience (as measured by questionnaires) and psychophysical measures of basic perceptual and cognitive functioning in this theoretical analysis of psychedelic effects.

A discussion of changes in consciousness that are associated with the psychedelic state can be divided into three broad categories: sensory and perceptual experience, cognitive capacities, and experiences relating to time, self, and space.

Visual imagery and perceptual meaning

Psychedelics were found to enhance visual imagery, including elements such as colours and complex imagery, and self-reports of hallucinogen experiences showed high semantic similarity with dream reports across large community-based self-report repositories.

Participants who have taken psychedelics report seeing objects in their environment as more salient and personally significant than they ordinarily do, and are also more likely to endorse items such as ‘Objects around me engaged me emotionally much more than usual’.

Laboratory-based studies have failed to find any evidence that ingesting psychedelics improves colour perception, and it is unclear how subjective reports of enhanced colour perception might be reconciled with the lack of objective evidence.

The bandwidth of consciousness

There is evidence that psychedelic drugs may cause an increase in the amount of sensory content that can enter consciousness at any given time, and that this increase is reflected in the reduced pre-pulse inhibition (PPI) response.

Research suggests that psychedelic drugs may increase the permeability of consciousness by increasing the frequency of saccadic eye-movements, which could allow for a greater sampling rate of sensory information as a person views their environment.

The subjective experience of the psychedelic state is associated with an increased intensity and volume of sensory information experienced at any given time, but less objective support for improvements in brightness or colour perception.

Psychedelics and cognition

In the state of ordinary alert wakefulness, conscious contents can guide and control a wide-range of cognitive and behavioural operations. However, these capacities are compromised in states of consciousness associated with brain trauma or epileptic seizures.

The psychedelic state appears to be strongly associated with impairments in cognitive and behavioural control, but also with increases in creativity and other aspects of cognitive function.

Memory, attention and communication

One study found that after consumption of LSD participants were unimpaired on tests of declarative memory, but showed impairments in tasks involving mental control and the manipulation of new items. However, measures of working memory were unimpaired.

Psychedelics have variable effects on memory, but consistent effects on attention. Psilocybin has been found to impair measures of sustained, divided, and covert orienting of attention.

Early reports indicate clear communication impairments during the psychedelic state, but it is unclear to what extent these impairments are related to the deficits in memory, attention, and mental control that we have reviewed.

Creativity, insight, and abstract thinking

One cognitive domain in which psychedelics have been said to augment functionality involves creativity. This is supported by an earlier line of research that found that psilocybin increased the availability of remote associations, but also suggested that this effect might be associated with cognitive impairments.

Psychedelics enhance the capacity to formulate novel thoughts, but they impair the capacity to distinguish genuinely insightful thoughts from those that merely seem to have those properties. The self-report data suggest that psychedelics impair the capacity to evaluate evidence and argument. The findings that psychedelics impair abstract thought are in line with the parallels that previous researchers have drawn between certain aspects of the psychedelic state and the psychotic state.

Psychedelics impair many aspects of cognition, including decision-making, memory, attention and abstract thought. They also impair the capacity to evaluate novel ideas and distinguish those that represent genuine cognitive advances from those that do not.

Psychedelics and the experience of unity (time, space and self)

Studerus et al. (2010) identified a single factor that accounted for a shared increased experience of unity relevant to both time and self.

Time

A key feature of the psychedelic state is a distorted experience of time, with subjects reporting that time has stopped or slowed. Several studies have shown that subjects’ ability to reproduce long temporal intervals is impaired in the psychedelic state.

Self and space

Psychedelics alter the experience of the self, with subjects often experiencing a breakdown in the perceived boundary between themselves and their environment. This phenomenon is often termed ‘ego-dissolution’.

Psilocybin was not as strongly associated with a sense of disembodiment as ketamine, which might reflect the fact that disembodiment requires a robust sense of the boundary between oneself and one’s environment.

General boundaries

The fact that items relating to self and time cluster together suggests that the underlying feature being captured here is a generalized weakening or dissolution of the natural boundaries and segmentation that structure perceptual experience.

Whether the experience of unity involves improvements or impairments in conscious processing partially depends on the nature of reality. The experience of ego-dissolution might be an important insight into reality, but it may also compromise cognitive and behavioural function.

Implication for Consciousness Science

The analysis of the psychedelic state puts further pressure on the idea that conscious states can be understood in terms of levels of consciousness. However, the psychedelic state is neither higher nor lower than the state of ordinary waking awareness.

This article questions the recent suggestion that psychedelics might be useful in treating patients with disorders of consciousness, because they impair certain aspects of cognition and have the potential to disrupt the perception of space, time and the self.

The rejection of the levels-based account suggests that some of the most influential theories of consciousness need to be significantly revised, for example the Global Workspace Theory (GWT), which assumes a rather simplistic conception of conscious states, needs to be developed so as to accommodate the multidimensional nature of consciousness.

The data reviewed in this paper pose a challenge to the Integrated Information Theory of consciousness, which equates a creature’s conscious state with its level of consciousness. However, it is far from clear that it is coherent to describe one individual as more or less conscious than another.

The analysis of the psychedelic state provides important data for attempts to develop a multidimensional account of conscious states. This account should be pursued in tandem with the investigation of other conscious states, such as those that are associated with sleep, sedation, and the post-comatose disorders of consciousness.

Psychedelics act predominantly through 5-HT2A receptor activation, and we know where these receptors are typically located in the brain. We can manipulate these receptors to understand the biological impact of their activation.

We have identified some of the more prominent changes in consciousness associated with psychedelic states, but the data we have used are too limited to allow for a formal assessment of the number of dimensions that would best characterise consciousness.