The influence of temporal frequency and wavelength on beta movement

The maximum displacement threshold for beta (apparent) movement was determined using small near-monochromatic stimuli subtending 2 min arc, over the frequency range 1.67-6.67 Hz. Displacement thresholds for the apparently oscillating spot were dependent upon both temporal frequency (F(9,903) = 1413) and wavelength (F(12,903) = 19.6), the stimuli having been equated for luminance. Significant interaction effects (F(108,903) = 3.32) demonstrated that the influence of colour varied with temporal frequency. It is suggested that short-range apparent movement over this frequency range may be mediated by a mechanism which is colour dependent.