Abstract
Several seconds of adaptation to a flickered stimulus makes a subsequently presented brief stimulus appear longer if it is static — temporal-dilation aftereffect, but shorter if it is flickered — temporal-constriction aftereffect. We demonstrated orientation specificity, eye selectivity, and insensitivity to adaptation frequency (for 5Hz and 20Hz; current study) for the temporal-dilation aftereffect, whereas others have demonstrated orientation independence, eye selectivity, and selectivity for faster adaptation frequency (20Hz effective but 5Hz ineffective) for the temporal-constriction aftereffect; these results suggested a role of cortical visual adaptation in temporal dilation and subcortical magno adaptation in temporal constriction. However, the two aftereffects were always measured with different methods, temporal dilation with a temporal-bisection task (comparing each test duration with memorized reference durations), and temporal constriction with a sequential-comparison task (comparing the reference duration presented at the adapted location with each test duration presented at a non-adapted location). We directly compared these aftereffects using the same temporal-bisection task to confirm that the dilation and constriction aftereffects reflect separate visual duration mechanisms rather than procedural artifacts. For a static test stimulus, both 5Hz and 20Hz adaptors produced temporal dilation. For a flickered test stimulus, a 5Hz adaptor still produced temporal dilation, but a 20Hz adaptor produced no effect rather than temporal constriction. However, when we measured the effect of the 20Hz adaptor at the adapted and non-adapted locations, perceived test duration was longer at the non-adapted location than at the adapted location, confirming the previous sequential-comparison result that the test duration was perceived to be shorter at the adapted relative to a non-adapted location. Overall, using a single psychophysical method, we demonstrate that flicker adaptation causes differential effects on the perceived duration of static and flickered stimuli, suggesting that the visual system implements separate duration calibration mechanisms for static and dynamic stimuli.
Meeting abstract presented at VSS 2012