Critical flicker frequency and the Pulfrich phenomenon.

The critical flicker frequency and the Pulfrich stereophenomenon were both used to investigate the long term effects on temporal resolution and visual latency of wearing a tinted lens in front of one eye for a period of five days. The results obtained from three subjects showed that in every case the critical flicker frequency was depressed by the tinted lens and displayed no adaptive recovery, but the Pulfrich effect displayed a reduction of apparent depth in the median plane indicating the presence of an adaptive recovery. It is postulated that the CFF indicates that the physiological transmission of the visual signal is unaltered over the the five days and the Pulfrich adaptation occurs due to an alteration of the interpretation of the unchanged visual response. That is, the adaptation is a perceptual rather than a physiological one.