Background and Aims:
Psychedelics are capturing a renewed attention of both the mainstream culture and the scientific community, in what has been called the psychedelic renaissance.

Psychedelic experiences can range from blissful to traumatic and predicting individual responses remains difficult. Extra-pharmacological factors have been proposed as important determinants of the quality of psychedelic experiences since the sixties. These factors include the set (one’s state of mind prior to taking the psychedelic) and the setting (the physical conditions were the psychedelic experience occurs).

This study aims to review the scientific literature from the ongoing psychedelic renaissance about the impact of extra-pharmacologic factors in acute psychedelic experiences.

Methods:
A systematic review was conducted after a Medline search using the terms ‘psychedelic’ AND ‘set’ OR ‘setting’. Only studies written in English and published after 1990 were considered. References were independently selected by the authors and then compared.

Results:
Factors from the set predictive of positive psychedelic experiences include absortion (the personality trait of being susceptible to immersion in experiences), psychological wellness prior to taking the drug, clear intentions and expectations about the experience and being open to the experience. On the other hand, set factors like neuroticism, anticipatory anxiety and low trust in accompanying persons are associated with negative experiences. Regarding the setting, certain types of music seems to facilitate positive experiences.

Conclusions:
The current psychedelic renaissance is aware of the influence of extra-pharmacologic factors in the acute effects of psychedelic drugs, but scientific studies have only begun to emerge and are mainly observational.

THE IMPORTANCE OF SET AND SETTING IN PSYCHEDELIC EXPERIENCES: A REVIEW