Self-report means the data come from what people say about themselves, rather than from a measurement taken by someone else. Psychedelic research leans on it heavily, because the experience itself can only be described by the person who had it. Scales such as the MEQ and the 5D-ASC are self-report tools.
Online surveys can reach thousands. In a survey of 10,836 ayahuasca users, 69.9% reported acute physical adverse effects, mainly vomiting (Bouso et al., 2022). A survey of 1,993 people described challenging psilocybin mushroom experiences in detail (Carbonaro et al., 2016). These studies capture rare events that small trials miss.
The trade-off is bias. Respondents choose to take part, may remember selectively, and often expect certain effects; surveys usually can’t check what substance or amount anyone took. That is why survey findings are treated as preliminary, and why trials pair self-report with clinician-rated scales such as the MADRS.
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