Abstract
Following prolonged exposure to asynchronous signals (whether audiovisual, audiotactile or visuotactile), the brain adapts or ‘recalibrates’ to reduce perceived asynchrony. Van der Burg, Alais and Cass (2013) showed temporal recalibration can also occur very rapidly for audiovisual stimuli, requiring only a single, asynchronous trial. Does rapid recalibration also occur between audiotactile and visuotactile stimuli? In separate audiovisual, audiotactile or visuotactile experiments, using the same participants, design, task, and spatially collocated stimuli (unlike the previous study), participants adapted to 180 asynchronous stimuli (+100ms or –100ms in separate blocks). Participants then performed a series of 180 synchrony judgements on the same stimulus pair at various SOAs [±400, ±200, ±100 ms]. Psychometric functions were fitted and the point of subjective synchrony (PSS) obtained. We conducted two analyses: 1) we pooled synchrony responses into 40-trial bins and plotted a walking average of the PSS over the test period; 2) we used inter-trial analyses to examine whether temporal recalibration occurred rapidly based on the stimulus order in the immediately preceding trial. The ‘walking average’ results revealed significant ‘modality order’ effects of prolonged adaptation for all conditions. Initial PSS shifts were equivalent for all three pairings (~25ms) and declined to baseline over time, although the AV effect lasted longer (36s) than VT (29s) and AT (27s). Inter-trial analysis revealed rapid temporal recalibration occurred for AV (21ms) and AT (14ms) conditions, but not for VT (1ms). Rapid recalibration magnitude did not decline and was stable throughout testing. The rapid AT recalibration effect here, absent in our previous study, strongly implicates spatial collocation as necessary for the AT effect. AV does not require collocation for fast or slow adaptation. VT shows no rapid recalibration but will recalibrate at a slow time-scale following sustained adaptation.
Meeting abstract presented at VSS 2015