Phenomenology of Psychedelic Experiences and Psychedelic-Associated Distressing Effects: Quantifying Subjective Experiences.

Psychedelic substances produce a wide range of effects on perception, cognition, and emotion, collectively called "psychedelic phenomenology." There is no agreement on which altered features, such as hallucinations or ego dissolution, define a "psychedelic state." This chapter reviews commonly discussed core features of psychedelic experiences, focusing on recent quantitative assessment methods rather than earlier phenomenological work. It also addresses under-researched distressing effects, or "challenging experiences" ("bad trips"), highlighting their importance for understanding therapeutic potential and risks. Historically, psychedelic phenomenology links to psychopathology. Refining assessment of distressing effects is stressed to identify factors promoting beneficial acute experiences and limiting potentially harmful long-term effects.

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Abstract

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.