Some aspects of the Pulfrich effect

Krekling, S. Some aspects of the Pulfrich effect. Scand. J. Psychol., 1973, 14, 87–90.-The course of the Pulfrich effect was studied as a function of binocular differences of intensity. A pendulum and a pointer were matched with respect to apparent distance, with one eye progressively dimmed by neutral density filters. The stereoscopic effect increased as a function of filter density, reached a maximum value and then decreased. At the point of reversal the apparent rotatory movement of the pendulum disappeared, coinciding with an abrupt increase in the variability of the subject's responses, probably indicating the transition to a qualitatively different visual process. The binocular-rivalry explanation of the reversal was not supported by the results.