Distorting the apparent duration of visual events

The perceived duration of a 500 ms sinusoidally modulated (10 Hz) Gaussian luminance blob is reduced by around 20% after adaptation to a higher (20 Hz) temporal frequency but is hardly affected by adaptation to a lower (5 Hz) temporal frequency (Johnston et al, 2006 Current Biology 16 472 - 479). This apparent temporal compression is not the result of differential delays of the perceived time of onset or offset of the pattern, which were independently measured by comparing the time of onset and offset against an auditory noise burst. Therefore adaptation does not act to modify the sensory signal. The temporal effect is not mediated by concomitant changes in apparent temporal frequency as adaptation to higher and lower temporal frequencies results in an apparent repulsion of test frequency whereas only adaptation to high temporal frequency reduces apparent duration. Adaptation to a very high temporal frequency (50 Hz), at or above the critical flicker fusion threshold, also leads to a reduction in the perceived duration for a 10 Hz test stimulus, implicating the magnocellular system in time compression