Effects of flicker modulation depth on the detection of changes in target location

Response times to a change in location of a small, low contrast target in a uniform flickering field were investigated under a range of flicker modulation depths. Increasing depth of modulation gave an increased response time for modulation depths from 0% (no flicker, to approx. 35%. Further increases in modulation depth had only a marginal effect on response time. It is shown that this effect is not due to flicker adaptation. The functional form of the modulation dependence is qualitatively similar to that reported by Badcock and Smith (1989, Vision Research, 29, 803-808), but shows a large difference in the modulation at which a levelling of performance occurred. It is shown that this difference is consistent with the presence of a third temporal filter, as proposed by Mandler and Makous (1984, Vision Research, 24, 1881-1887).