Thomas Kappeler

Measurement of handwriting area to pressure ratios during psilocybin-induced hallucinations

We define hallucinations as experiences of intense sensations (S) during which the ability and intention for verification through voluntary motor (M) performance is damped or blocked. We have set out to quantify the high sensory to motor (S/M) ratio implicit in a hallucinatory experience by inducing the latter through the administration of 160 μg/kg psilocybin to 16 college-age volunteers. Handwriting area in cm2 (S) and handwriting pressure in 104 dyn (M) — averaged over time and obtained through a pressure transducer and a voltage-to-frequency converter —were chosen as sensory and motor parameters for the computation of S/M ratios.One of the more important results reveals that although for the group of volunteers the mean handwriting area increases from pre-drug to drug peak — while copying four times a 28-word text — the mean handwriting pressure decreases for only thirteen of them and increases for three. Through the administration of the Myers-Briggs indicator, a self-reporting personality inventory based on Jungian typology, we could differentiate between (1) the thirteen ‘perceivers’, as subjects characterized by a high S/M ratio during their psilocybin-induced intensely hallucinatory experiences, and (2) the three ‘judgers’ who attempt to maintain a low S/M ratio at drug peak and whose response to psilocybin results in a controlled, shorter, non-hallucinatory experience.Another noteworthy result is the personality trait dependent nature of the ‘dissociation’ which prevails between the extent of drug-induced autonomic activity, expressed in terms of increase in pupillary diameter, and the extent and direction of drug-induced perceptual and behavioral change. This ‘dissociation’ is carried almost entirely by the ‘perceivers’ but not by the ‘judgers’.