PERCEPTUAL INTEGRATION OF MOTION AND FORM INFORMATION - IS THE MOVEMENT FILTER INVOLVED IN FORM DISCRIMINATION

Seven experiments reinvestigated J. Driver and P. McLeod's (1992) repo rt of a ''visual search asymmetry reversal'' in a task that required t he integration of motion and form information. They found that, when t he form discrimination was easy, search was more efficient for a movin g rather than a stationary conjunction target; the reverse was true wh en form discrimination was difficult. J. Driver and P. McLeod proposed that 2 mechanisms are involved: a ''stationary form system,'' which s upports accurate form discrimination but is relatively insensitive to movement, and a ''movement filter,'' which segregates the moving from the stationary items but is relatively insensitive to aspects of form. The present experiments failed to find the asymmetry reversal. The re sults agree with the (more parsimonious) proposal that the function of the movement filter is limited to separating moving from stationary i tems, whereas form discrimination is accomplished within a unitary for m system.