Ayahuasca enhances creative divergent thinking while decreasing conventional convergent thinking

Ayahuasca is a traditional South American plant brew that contains the serotonergic 5-HT2A agonist N,N-dimethyltryptamine (DMT) together with monoamine oxidase–inhibiting β-carboline alkaloids, rendering oral DMT active. Earlier work has reported acute visionary effects, mixed findings on cognition depending on user experience, no evidence of long-term cognitive harm in follow-up studies, and potential therapeutic benefits for substance use disorders and depression. Psychedelics more broadly have been associated with lasting changes in well‑being and reductions in psychological distress in population surveys. Separate studies indicate that ayahuasca can enhance mindfulness-related capacities and reduce judgmental processing, and neuroimaging work has found altered connectivity in networks implicated in cognition and perception after ayahuasca ingestion. Kuypers and colleagues framed creative thinking—distinguishing divergent thinking (generating many novel ideas) from convergent thinking (finding a single correct solution)—as a psychological facet that could be modulated by ayahuasca and might contribute to therapeutic change through increased psychological flexibility. The present quasi‑experimental study therefore set out to assess whether acute ayahuasca intake alters divergent and convergent creative thinking. Creativity was measured before and during the acute inebriation in two separate ayahuasca‑using groups to test whether effects were robust across settings and participant characteristics.

The study used a quasi‑experimental, pre/post design conducted in two separate non‑religious ayahuasca workshop groups. A total of 26 participants consented and completed testing: group 1 (n = 15; mean age 37.4 years; 10 women) and group 2 (n = 11; mean age 52.0 years; 7 women). All participants had prior ayahuasca experience (group 1 mean ~27.5 occasions; group 2 mean ~103.6 occasions). Exclusion criteria included current psychiatric disorders, alcohol or other substance use disorders, and significant current medical illness. Participants abstained from ayahuasca, other psychotropics, alcohol and medications for at least 2 days before testing. The protocol received local ethics approval and all volunteers gave written informed consent. Assessments occurred twice for each participant: a baseline session approximately 3 hours before the ceremony, and a post‑dose assessment during acute intoxication roughly 1.5–2 hours after the initial dose (a second optional dose was offered later). Two parallel versions of the creativity battery were administered in counterbalanced order; total testing time was about 35 minutes. The investigators recorded total ayahuasca volume consumed and collected 10 ml samples of each tea for alkaloid quantification using liquid chromatography–tandem mass spectrometry. Alkaloid concentrations differed between the two groups' teas. Group 1's tea contained 0.65 mg/ml DMT, 0.84 mg/ml harmine, 0.76 mg/ml tetrahydroharmine and 0.10 mg/ml harmaline; mean total ingestion was 116.7 ml (≈75.5 mg DMT). Group 2's tea contained 0.96 mg/ml DMT, 0.48 mg/ml harmine, 0.69 mg/ml tetrahydroharmine and 0.10 mg/ml harmaline; mean total ingestion was 44.5 ml (≈42.8 mg DMT). Two creativity tasks were used. The Picture Concept Task (PCT) assesses convergent thinking by asking participants to select the one correct association between rows of pictures; divergent thinking was measured by instructing participants to list as many alternative associations as possible for each stimulus, producing fluency (number of alternatives), originality (scored relative to others' responses: unique = 2, shared with one = 1, shared by 3+ = 0) and a ratio originality/fluency. Twenty‑eight PCT stimuli were shown with 1 minute per item. The Pattern/Line Meanings Task (PLMT) asked participants to generate multiple meanings for abstract patterns (eight items, 2 minutes each), with fluency and originality scored similarly. After the acute phase subsided, participants completed multiple visual analogue scales (VAS; 0–100) rating aspects of the ayahuasca experience (visuals, bodily sensations, emotions, memory phenomena, unity, well‑being, etc.). Statistical analysis used IBM SPSS v21. Independent t tests compared sociodemographic variables between groups. Primary inferential testing employed a mixed factorial general linear repeated measures model with group (1, 2) as the between‑subjects factor and ayahuasca (before, after) as the within‑subjects factor. VAS scores were analysed within each group using one‑sample t tests against zero (based on prior work indicating negligible placebo VAS scores) and between groups via independent t tests. Significance was set at p = .05.

Groups differed significantly on demographic variables: group 2 was older than group 1 (mean difference 14.6 years; t = -3.47; p = .004) and had slightly more education (mean difference 2.9 years; t = -3.04; p = .006). The number of prior ayahuasca occasions did not differ significantly between groups. Subjective effects rated on VAS were significantly elevated relative to zero in both groups across the measured items (group 1 and group 2 one‑sample t tests all significant, p values ranged approximately from ≤ .001 to .023 and ≤ .001 to .017 respectively). No significant differences between groups were found on VAS mean scores. Creativity task performance showed task‑ and measure‑specific effects. For the PCT (which yields both convergent and divergent measures), there was a main effect of group on fluency, originality and the originality/fluency ratio: group 1 produced higher fluency and originality scores than group 2, while group 2 had a higher ratio score. An interaction between ayahuasca and group was observed for PCT fluency: under ayahuasca, fluency decreased in group 1 relative to baseline but increased in group 2. Importantly, a main effect of ayahuasca on the PCT ratio (originality corrected for fluency) indicated that originality per unit of fluency increased during the acute ayahuasca state compared with baseline. By contrast, the PLMT showed no significant effects of ayahuasca, group, or their interaction on any dependent measures. Convergent thinking, operationalised as the number of correct responses on the PCT, declined after ayahuasca ingestion compared with baseline (main effect of ayahuasca). There was no significant main effect of group on correct PCT responses.

Kuypers and colleagues interpret their findings as showing an acute double dissociation: ayahuasca increased measures of creative divergent thinking (improved originality when adjusted for fluency on the PCT) while impairing conventional convergent thinking (fewer correct PCT solutions) during the intoxication period. The lack of effects on the PLMT led the authors to note that stimulus complexity may matter—the PCT stimuli are colourful and more complex and may have elicited richer associations than the simpler black‑and‑white PLMT stimuli. The investigators link these behavioural effects to prior neurobiological findings on psychedelics, proposing that altered thalamic gating, changes in default mode, salience and central executive network interactions, increased integration across normally distinct networks, and reduced top‑down control could promote associative, bottom‑up processing and thus enhance divergent thinking while disrupting the focused processing needed for convergent solutions. They acknowledge that the precise neural mechanisms remain uncertain and that previous imaging work presents a complex picture rather than a single unifying change. Several limitations are acknowledged. The quasi‑experimental design and the lack of a placebo control limit causal inference and raise the possibility of order or practice effects; the authors argue that counterbalancing of test versions and the observed double dissociation mitigate this concern but do not eliminate it. Mood may have influenced divergent thinking, but mood was measured only after ayahuasca so baseline comparisons were not possible. The investigators also note the sample comprised experienced, self‑selected ayahuasca users in non‑religious workshop settings, which constrains generalisability. They recommend future placebo‑controlled studies incorporating baseline and longitudinal mood measures, additional creativity tasks that assess usefulness (for example alternate uses tests), and follow‑up assessments to determine whether convergent thinking recovers or other cognitive changes persist beyond the acute phase. In terms of implications, the authors suggest the acute enhancement of divergent thinking could facilitate psychotherapeutic processes by allowing patients to recall events and form novel associations more freely, while sub‑acute integration sessions might then be used to translate insights into adaptive strategies. Nonetheless, they emphasise that while ayahuasca may promote psychological flexibility relevant to therapy, the concurrent acute impairment of convergent thinking means further controlled research is required before clinical applications can be recommended.