Inverse-intensity effect in duration of visible persistence.

Duration of visible persistence can vary inversely with stimulus intensity. This inverse-intensity effect is obtained by varying the intensity of the stimuli or of the background, provided that the variations extend into the mesopic range. A similar relationship--known as the Ferry-Porter law--holds for the critical frequency at fusion (CFF). The authors propose that studies of CFF, 2-pulse threshold, and visible persistence can be encompassed within 1 conceptual framework in which the effect is modeled by the progressive reduction in the temporal extent of the positive phase of the system's response as the level of light adaptation changes from scotopic to photopic. In this context, the authors present an integrative scheme in which G. Sperling and M. M. Sondhi's (1968) formal model and M. Coltheart's (1980) neurophysiological conjecture are shown to be compatible and complementary accounts of the effect.