Fig. 4.

Correlations between plasma LSD concentrations and subjective peak effects. a At 200 μg, LSD induced high ratings of audio-visual synesthesia in all but two of the 16 participants. There was little variance in the response and no correlation between total plasma exposure to LSD (area under the concentration-time curve [AUC]) and audio-visual synesthesia (R _p = 0.0, p > 0.05, n = 16). b In contrast, ego dissolution was present to highly variable degrees across subjects after administration of 100 μg LSD. Total exposure to LSD (AUC) positively correlated with LSD-induced ego dissolution (R _p = 0.51, p < 0.05, n = 24). The lines indicate the regression and 95 % confidence intervals