A Plea for the Scientific Study of the Diversity of Consciousness: Towards a Multidimensional Definition of Altered States of Consciousness

Scientific studies of consciousness have been blooming within the last decades. The present article aims to widen and deepen this research program by highlighting the importance of the diversity of conscious states throughout lifetime and across cultures, practices, conditions and pharmacological manipulations. Some psychologists and neuroscientists have recently recognized that their investigations had so far only concerned a limited, non-representative and WEIRD sample of humans. Taking up this argument and applying it to the domain of consciousness, I argue that the scientific study of consciousness should be radically extended by going beyond the usual study of standard participants and standard states of consciousness. Although the study of altered states of consciousness (ASCs) is promising and should enable the science of consciousness to make significant discoveries, it must be acknowledged that the concept of ASC has long been plagued by both conceptual and empirical limitations. After having presented some of the classical models of ASCs and having shown their weaknesses and shortcomings, I introduce more recent models developed by neurologists, neuropsychiatrists, neuropsychologists and computational neuroscientists and I subsequently argue that these new multidimensional models of consciousness can help us redefine the concept of ASC in a satisfactory manner. Drawing upon these innovating models, I finally make a plea for a systematic study of consciousness which would account for the diversity of ASCs at a phenomenological, physiological and etiological level.