The Ego Dissolution Inventory (EDI) is a short self-report scale for ego dissolution, the weakening of the usual sense of being a separate self. It was validated in 2016 in 691 participants, and scores rose with dose for psychedelics but not for cocaine or alcohol (Nour et al., 2016).
It is now one of the standard questionnaires in psychedelic lab studies, alongside measures of mystical experience (Nour et al., 2016). It has also travelled beyond drugs: among 100 people who had near-death experiences, EDI scores were higher than ego-inflation scores and correlated with measures of out-of-body intensity and unity (Martial et al., 2021).
The EDI asks what a person remembers, so it shares the limits of all self-report measures. A high score says the experience was felt as a loss of self; it does not say whether that was calm or frightening. For that, researchers pair it with scales such as the Challenging Experience Questionnaire or the 5D-ASC.
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