Features derived from first-order motion mechanisms predict anomalies in motion perception

Current dominant hypotheses of how humans detect the movement of patterns assume that the pattern is divided into one-dimensional sinusoidally varying luminance patterns, referred to as gratings (first-order components). The speed of these gratings is independently encoded from predominantly spatial and temporal frequency information, and their direction is encoded from orientation information. This paper addresses the problem of how the individually encoded grating information is combined to give perceived pattern direction, given that real moving objects are generally made up of more than one component. More specifically, further evidence is presented for a combination based on the use of a feature derived from first-order components--'first-order feature hypothesis'. This hypothesis essentially implements a constraint on pattern direction called the intersection of constraints (IOC) proposed by Adelson and Movshon [1982, Nature 300 523-525]. A simulation of the model is used to make three new predictions about a perceived motion reversal reported by Derrington et al (1992, Vision Research 32 699-707); these predictions are tested and found to be consistent with the first-order feature hypothesis.