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.
Fischer, R., et al. (1970). “Psilocybin-induced contraction of nearby visual space.” Agents and Actions 1(4): 190-197.