Second-Order Motion Perception: Space/Time Separable Mechanisms

摘要

Microbalanced stimuli are dynamic displays which do not stimulate motion mechanisms that apply standard (Fourier-energy or autocorrelational) motion analysis directly to the visual signal. Because they bypass such first-order mechanisms, microbalanced stimuli are uniquely useful for studying second-order motion perception (motion perception served by the mechanisms that require a grossly nonlinear stimulus transformation prior to standard motion analysis). Some stimuli are microbalanced under all pointwise stimulus transformations and therefore are immune to early visual nonlinearities. These are used to disable motion information derived from spatial (temporal) filtering in order to isolate the temporal (spatial) properties of space/time separable second-order motion mechanisms. The motion of all of the microbalanced stimuli one considers can be extracted by (1a) band-selective spatial filtering and (1b) biphasic temporal filtering, nonzero in dc, followed by (2) a rectifying nonlinearity and (3) standard motion analysis. Reprints. (jhd)