Altered states of consciousness
Explanation
Altered states of consciousness (ASC) are patterns of experience different from the normal waking state, with changes in perception, cognition, emotion, sense of self, sense of time and/or sense of space. Charles Tart, American psychologist, systematised this field in the 1970s with his book Altered States of Consciousness (1969), in which he gathered studies on meditation, hypnosis, dreams, psychedelic drugs, trance, mystical experiences and other states, showing that human consciousness is enormously diverse phenomenologically.
Tart proposed an operational definition. An ASC is a state in which the subject experiences a qualitative alteration in the general pattern of mental functioning, such that he himself (not just an external observer) recognises that his consciousness is functioning differently from usual. This definition emphasises the first-person phenomenological report, recalling that the study of consciousness cannot dispense with subjective experience.
The taxonomy of ASCs includes very diverse categories: dreaming states (REM sleep, lucid dreams), meditative states (concentration, absorption, jhanas, non-duality), hypnotic states, drug-induced states (psychedelics, dissociatives, cannabis, alcohol, opiates), ecstatic states (ritual trance, dance, possession, glossolalia), peak experiences, mystical experiences, near-death experiences, sensory-deprivation states, febrile states, dissociative fugues, depersonalisation, etc.
Each category has its own characteristic phenomenology, including typical changes in variables such as sense of time (accelerated, slowed, eternal), sense of self (intensified, weakened, dissolved, fragmented), perception (more vivid, synaesthetic, hallucinatory), cognition (more associative, symbolic, intuitive), emotion (more intense, broader, transformed). Systematic mapping of these variations enables intersubjective comparisons and theory-building.
For the theory of consciousness, ASCs are indispensable because they reveal the plasticity and structural plurality of the mind. Ordinary consciousness is only one of many possible configurations of the mental apparatus. Studying ASCs sheds light on questions such as: what conditions make different modes of experience possible, what is preserved and what changes between states, what does phenomenological diversity tell us about the nature of consciousness, what neural bases these variations have.
The field has had renewed interest with the resurgence of psychedelic research (Carhart-Harris, Griffiths, Pollan), with the development of contemplative neuroscience (Davidson, Saron), and with theoretical proposals such as the entropic brain (the idea that some ASCs correspond to increases in brain activity entropy, with decrease of the ego's predictive control). ASCs, traditionally marginalised or pathologised, are today a legitimate part of the empirical study of consciousness.
Strengths
- A robust descriptive framework for phenomenologically diverse phenomena.
- Recognises genuine variability of human consciousness.
- Useful cartography for interdisciplinary research.
- Dialogue with anthropology and contemplative traditions.
Main critiques
- Heterogeneous operationalisation between researchers.
- Risk of treating as unitary what are very different phenomena.
- Difficulty of intersubjective measurement without verbal reports.