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A placebo-controlled investigation of synaesthesia-like experiences under LSD.

Devin B. Terhune, David Luke, Mendel Kaelen, Mark Bolstridge, Amanda Feilding, David Nutt, Robin Carhart-Harris, Jamie Ward

Neuropsychologia April 5, 2016 DOI: 10.1016/j.neuropsychologia.2016.04.005 (opens in new tab)

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Study at a glance

AI-extracted from the abstract
Characteristics Within-groups placebo-controlled pilot study Peer reviewed
Intervention Lysergic acid diethylamide (LSD)
Topics Altered states of consciousness LSD
Keywords Synaesthesia Cross-sensory perception Blended senses Sensory blending Psychedelics Hallucinogens Compound Altered perception Sensory experience Sensory processing Sensory integration Brain function Neural processing Cognitive neuroscience
Citations 45
Key points LSD-induced synaesthesia-like experiences do not exhibit consistency or inducer-specificity and thus do not meet two widely established criteria for genuine synaesthesia.

Abstract

The induction of synaesthesia in non-synaesthetes has the potential to illuminate the mechanisms that contribute to the development of this condition and the shaping of its phenomenology. Previous research suggests that lysergic acid diethylamide (LSD) reliably induces synaesthesia-like experiences in non-synaesthetes. However, these studies suffer from a number of methodological limitations including lack of a placebo control and the absence of rigorous measures used to test established criteria for genuine synaesthesia. Here we report a pilot study that aimed to circumvent these limitations. We conducted a within-groups placebo-controlled investigation of the impact of LSD on colour experiences in response to standardized graphemes and sounds and the consistency and specificity of grapheme- and sound-colour associations. Participants reported more spontaneous synaesthesia-like experiences under LSD, relative to placebo, but did not differ across conditions in colour experiences in response to inducers, consistency of stimulus-colour associations, or in inducer specificity. Further analyses suggest that individual differences in a number of these effects were associated with the propensity to experience states of absorption in one's daily life. Although preliminary, the present study suggests that LSD-induced synaesthesia-like experiences do not exhibit consistency or inducer-specificity and thus do not meet two widely established criteria for genuine synaesthesia.

Comparable studies

Other randomized controlled trials on LSD, most cited first.

Study Year Design Participants
Safety and Efficacy of Lysergic Acid Diethylamide-Assisted Psychotherapy for Anxiety Associated With Life-threatening Diseases Patients with anxiety associated with life-threatening diseases 2014 Randomized controlled trial n = 12
Dose-Response Study of N,N-Dimethyltryptamine in Humans Experienced hallucinogen users 1994 Double-blind, saline placebo-controlled, randomized study n = 12
Acute Effects of Lysergic Acid Diethylamide in Healthy Subjects Healthy subjects (8 women, 8 men) 2014 Double-blind, randomized, placebo-controlled, crossover study n = 16
Changes in global and thalamic brain connectivity in LSD-induced altered states of consciousness are attributable to the 5-HT2A receptor Healthy human participants 2018 Double-blind, randomized, counterbalanced, cross-over study n = 24
LSD-induced entropic brain activity predicts subsequent personality change. Healthy adults 2016 Balanced-order, placebo-controlled study n = 19

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Altered states of consciousness LSD Philosophy of mind