Psilocybin-induced contraction of nearby visual space
Using apparent fronto-parallel plane (AFP) monitoring techniques, the relative stability of the abathic plane, i.e. Euclidean visual space, was investigated in 16 volunteers with a median age of 23.5 years under 160 μg/kg psilocybininduced ergotropic arousal. Handwriting area and pressure were also measured in the same subjects.
Drug-induced contraction of nearby visual space was inferred from changes of AFP curvature and tilt, as well as from increased handwriting area at drug peak. The ‘rising horizon’ (Rennert) in the drawings of schizophrenics is also considered a manifestation of the contraction of visual space and is described in terms of an arousal-dependent transformation of constancies. The ‘projection’ of central nervous system activity as experience ‘out there’ is also discussed as an arousal-dependent learned constancy.