Abstract
Goals: Endogenous selective attention to one of two competing visual motion signals of the same spectral composition skews the ensuing motion aftereffect (MAE) in favor of the attended signal (e.g., Lankheet & Verstraten, 1995; von Grunau et al., 1998). We studied this effect with competing signals of different spectral composition in both the visual and auditory modalities.
Methods: Adaptation stimuli comprised two competing motion signals of different spectral features moving in opposite directions. The visual adaptation stimuli consisted of sinusoidal gratings at 0.5 and 2 cycles/degree; the test stimulus was at an intermediate frequency. Non-overlapping auditory adaptation stimuli contained four low-frequency ‘C’ (131-1,046Hz) and four high-frequency ‘F#’ (1,475-11,840Hz) notes. The test stimulus contained five intermediate-frequency ‘D’ notes (294-2,349Hz); the range of the test notes overlapped the two adaptation ranges equally in the log (frequency) scale. Within a block of trials, subjects attended to the motion signal carried by low (or high) frequencies during adaptation. The direction of attended frequency was randomized across trials. Subjects reported the direction and duration of the ensuing MAE. We measured static and dynamic durations for visual MAE; nulling strength and duration for auditory MAE.
Results: Attention to spectral features played a significant role in modulating the ensuing MAE. A significant attentional modulation of auditory MAE was observed with both measures. The visual MAE direction was consistent with the frequency contingency of MAE (Shioiri & Matsumiya, 2006): low/high spatial-frequency adaptation signals dominated the dynamic/static MAE. However, there was a significant attentional modulation of MAE duration.
Conclusions: Our findings that selective attention to one of two spectral components that move in opposite directions during adaptation influences the subsequent MAE complement earlier findings of same-frequency adaptation in the visual modality, and extend these findings to the role of attention in the auditory modality.