An independent effect of spatial frequency on motion integration reveals orientation resolution

PROBLEM To investigate the independent role of spatial frequency on component motion integration. METHOD Two Type II plaids were presented at varying spatial frequencies. The velocity vectors of the underlying components were constructed so that predicted speed and direction from the components; the Intersection of Constraints; the vector average; and distortion products, remained constant for each of the two plaids across spatial frequency. Perceived direction was measured using a method of adjustment. RESULTS Perceived direction changed as a function of spatial frequency, approaching the pattern direction only at spatial frequencies greater than 0.5cpd. CONCLUSIONS Spatial frequency has an independent effect on the component integration stage that determines perceived pattern motion direction. The results appear to reflect the resolution of orientation for recombination of the components at low spatial frequencies. These results have implications for motion modelling and possible clinical applications.