Outcome variable assumption checks revealed problems with the normality assumption on negative emotion, anxiety, and sadness words and problems with homoscedasticity on positive emotion, negative emotion, anxiety, sadness words, OAV scale semantic similarity, and Hood’s M scale semantic similarity scores. As a consequence, we used ggstatsplot’s robust option for positive emotion words, OAV scale similarity index, and Hood’s M scale similarity index and the nonparametric option for negative emotion, anxiety, and sadness words and interpreted the results appropriately. Due to normality and homoscedasticity violations on age and weight, respectively, we also used appropriate alternative tests for these variables.
Table 2 compares report writers’ demographic data by substance, and online supplementary Figs. S1 and S2 visualize significant differences between drugs on age and weight. There were significant effects for the distribution of age in years, χ2 (5) = 48.86, p < 0.001 and ε2ordinal = 0.06; weight in kilograms, Ftrimmed-means (5,475.72) = 8.83, p < 0.001, ξ2 = 0.18; and gender, χ2 (5) = 118.65, p < 0.001. LSD report writers were of the youngest age (Median = 20.00), being significantly younger than Ayahuasca and DMT (Median = 24.00, p < 0.001), psilocybin (Median = 23.00, p < 0.001), and antidepressant report authors (Median = 24.00, p = 0.001). MDMA report writers (Median = 21.00) were significantly younger than Ayahuasca and DMT (p < 0.001), psilocybin (p = 0.007), and antidepressant report authors (p = 0.008). MDMA report authors had the lowest trimmed-mean weight (M = 66.26), being significantly lighter than Ayahuasca and DMT (M = 72.56, p < 0.001), psilocybin mushroom (M = 69.38, p = 0.045), and antidepressant report authors (M = 71.73, p = 0.006). Ayahuasca and DMT report authors were also significantly heavier than LSD report authors (M = 68.56, p = 0.007). Based on the expected cell proportions for gender, there were significantly fewer female report writers than expected in the Ayahuasca and DMT (p < 0.001), ketamine (p < 0.01), and psilocybin mushroom report groups (p < 0.001). In the MDMA group, there were significantly more female report writers than expected (p < 0.001).
Table 2 Summary of sample demographics Figure S3 displays the trimmed-means ANOVA results and significant pairwise comparisons for the affective process words outcome. There was a significant report group effect, Ftrimmed-means (5503.16) = 75.66, p < 0.001 and ξ2 = 0.45, CI 95% (0.40, 0.51). Bonferroni-corrected post hoc tests showed that MDMA reports were associated with the highest proportion of affective process words (M = 5.26), significantly higher than in psilocybin mushroom (M = 4.28, p < 0.001), LSD (M = 4.26, p < 0.001), Ayahuasca and DMT (M = 3.71, p < 0.001), and ketamine reports (M = 3.71, p < 0.001). Moreover, antidepressant reports featured a significantly higher proportion of affective process words than Ayahuasca and DMT (p < 0.001), ketamine (p < 0.001), LSD (p < 0.001), and psilocybin mushroom reports (p < 0.001). Finally, Ayahuasca and DMT and ketamine reports featured a significantly lower proportion of affective process words than LSD and psilocybin mushroom reports, respectively (all p < 0.001).
Figure 1 displays trimmed-means ANOVA results and significant pairwise comparisons for the positive emotion words outcome. There was a significant report group effect, Ftrimmed-means (5512.70) = 88.76, p < 0.001 and ξ2 = 0.50, CI 95% (0.43, 0.57). Post hoc comparisons showed that the MDMA reports (M = 3.40) featured a significantly higher positive emotion word proportion than the psilocybin mushroom (M = 2.45, p < 0.001), LSD (M = 2.35, p < 0.001), Ayahuasca and DMT (M = 2.30, p < 0.001), ketamine (M = 2.05, p < 0.001), and antidepressant reports (M = 1.90, p < 0.001). Furthermore, the antidepressant reports featured a significantly lower positive emotion word proportion than Ayahuasca and DMT (p = 0.001), LSD (p < 0.001), and psilocybin mushroom reports (p < 0.001). Finally, ketamine reports featured significantly a lower positive emotion word proportion than psilocybin mushroom (p < 0.001) and LSD reports (p = 0.027).
Figure 2 displays the Kruskal–Wallis test results and significant pairwise comparisons for the negative emotion words outcome. There was a significant report group effect, χ2 (5) = 284.92, p < 0.001 and ε2ordinal = 0.10, CI 95% (0.08, 0.12). Post hoc comparisons showed that Ayahuasca and DMT reports (Median = 1.23) featured a significantly lower median proportion of negative emotion words than MDMA (M = 1.60, p < 0.001), psilocybin mushroom (Median = 1.62, p < 0.001), LSD (M = 1.64, p < 0.001), and antidepressant reports (Median = 2.97, p < 0.001). Antidepressant reports (Median = 2.97) featured a higher median proportion of negative emotion words than ketamine reports (Median = 1.49, p < 0.001) and all other report groups (all p < 0.001).
Figure S4 displays the Kruskal–Wallis test results and significant pairwise comparisons for the sadness words outcome. There was a significant report group effect, χ2 (5) = 79.44, p < 0.001 and ε2ordinal = 0.03, CI 95% (0.02, 0.04). Post hoc comparisons showed that Ayahuasca and DMT reports (Median = 0.23) featured a lower median proportion of sadness words than LSD (Median = 0.26, p = 0.029), psilocybin mushroom (Median = 0.28, p = 0.001), MDMA (Median = 0.30, p = 0.001), and antidepressant reports (Median = 0.57, p < 0.001). Antidepressant reports featured a higher median proportion of sadness words than each of the other report groups (all p < 0.001).
Figure S5 displays the Kruskal–Wallis test results and significant pairwise comparisons for the anxiety words outcome. There was a significant report group effect, χ2 (5) = 21.70, p = 0.001 and ε2ordinal = 0.01, CI 95% (0.00, 0.02). Post hoc comparisons showed that ketamine reports (Median = 0.27) featured a lower median proportion of anxiety words than psilocybin mushroom (Median = 0.42, p = 0.002), LSD (Median = 0.41, p = 0.010), and antidepressant reports (Median = 0.46, p = 0.006).
Figure 3 displays the ANOVA results and significant pairwise comparisons for the cognitive process words outcome. There was a significant report group effect, F (5,2941) = 14.29, p < 0.001 and η2p = 0.02, CI 95% (0.01, 0.03). Bonferroni-corrected post hoc tests showed that Ayahuasca and DMT reports were associated with the lowest proportion of cognitive process words (M = 11.77), significantly lower than that of MDMA (M = 12.71, p < 0.001), ketamine (M = 12.93, p < 0.001), and antidepressant reports (M = 13.02, p < 0.001). Psilocybin mushroom reports (M = 12.06) featured a significantly lower proportion of cognitive process words than MDMA (p < 0.001), ketamine (p = 0.001), and antidepressant reports (p < 0.001). LSD reports (M = 12.15) featured a significantly lower proportion of cognitive process words than MDMA (p = 0.002), ketamine (p = 0.006), and antidepressant reports (p < 0.001).
Figure 4 displays the ANOVA results and significant pairwise comparisons for the analytical thinking index. There was a significant substance group effect,Footnote 1F (5, 2941) = 19.31, p < 0.001, η2p = 0.03, and CI 95% (0.02, 0.04). Bonferroni-corrected post hoc tests showed that Ayahuasca and DMT reports scored highest on the analytical thinking index (M = 60.60), significantly higher than LSD (M = 56.36, p = 0.003), antidepressant (M = 53.85, p < 0.001), and MDMA reports (M = 50.61, p < 0.001). MDMA reports scored significantly lower than ketamine (M = 55.79, p = 0.016), LSD (p < 0.001), and psilocybin mushroom reports (M = 58.46, p < 0.001). Psilocybin mushroom reports also scored significantly higher than antidepressant reports (p = 0.005).
Figure 5 displays the trimmed-means ANOVA results and significant pairwise comparisons for the OAV scale similarity index. There was a significant report group effect, F (5526.38) = 122.75, p < 0.001, ξ2 = 0.58, and CI 95% (0.51, 0.65). Yuen’s trimmed-means tests showed that Ayahuasca and DMT reports featured the greatest semantic similarity with the OAV scale (M = 0.19), significantly greater than antidepressant (M = 0.05, p < 0.001), ketamine (M = 0.11, p < 0.001), LSD (M = 0.11, p < 0.001), MDMA (M = 0.11, p < 0.001), and psilocybin mushroom reports (M = 0.12, p < 0.001). Antidepressant reports featured the least semantic similarity with the OAV scale, significantly less than ketamine (p < 0.001), LSD (p < 0.001), MDMA (p < 0.001), and psilocybin mushroom reports (p < 0.001).
Figure 6 displays the trimmed-means ANOVA results and significant pairwise comparisons for the Hood’s M scale similarity index. There was a significant substance group effect, F (5519.46) = 84.76, p < 0.001 and ξ2 = 0.57, CI 95% (0.50, 0.65). Yuen’s trimmed-means tests showed that Ayahuasca and DMT reports featured the greatest semantic similarity with Hood’s M scale (M = 0.14), significantly greater than antidepressant (M = 0.03, p < 0.001), ketamine (M = 0.06, p < 0.001), LSD (M = 0.07, p < 0.001), MDMA (M = 0.04, p < 0.001), and psilocybin mushroom reports (M = 0.06, p < 0.001). Antidepressant reports featured the least semantic similarity with Hood’s M scale, significantly less than ketamine (p < 0.001), LSD (p < 0.001), and psilocybin mushroom reports (p < 0.001). Also, MDMA reports scored lower on similarity with Hood’s M scale than ketamine (p = 0.031), LSD (p < 0.001) and psilocybin reports (p < 0.001); and psilocybin reports scored lower than LSD reports (p = 0.038).