Estimating the duration of gratings under masking and nonmasking conditions

Previous research has shown that the subjective duration of very short time intervals decreases with the increase of spatial frequency (SF) and this effect is supposed to be mediated by an early peripheral component of the persistence process called "retinal persistence". As the retinal components of persistence are very likely to be erased by a mask, we suggest that if retinal persistence underlies SF influence on duration estimation, the introduction of a mask would make subjective duration independent of SF. This inference was tested estimating the duration of presentation of square-wave gratings of equal mean luminance and contrast (85%) and of varying SF under two conditions: with and without a mask. Subjective duration decreased with the increase of SF under both experimental conditions It was concluded that retinal persistence does not underlie the SF effect on brief duration perception. Rather, the apparent contrast of the gratings covarying with SF could account for SF influence on perceived duration.