Orienting Attention to Points in Time Improves Stimulus Processing Both within and across Modalities

Abstract

Spatial attention affects the processing of stimuli of both a task-relevant and a task-irrelevant modality. The present study investigated if similar cross-modal effects exist when attention is oriented to a point in time. Short (600 msec) and long (1,200 msec) empty intervals, marked by a tactile onset and an auditory or a tactile offset marker, were presented. In each block, the participants had to attend one interval and one modality. Event-related potentials (ERPs) to auditory and tactile offset markers of attended as compared to unattended intervals were characterized by an enhancement of early negative deflections of the auditory and somatosensory ERPs (audition, 100-140 msec; touch, 130-180 msec) when audition or touch was task relevant, respectively. Similar effects were found for auditory stimuli when touch was task relevant. An additional reaction time experiment revealed faster responses to both auditory and tactile stimuli at the attended as compared to the unattended point in time, irrespective of which modality was primary. Both behavioral and ERP data show that attention can be focused on a point in time, which results in a more efficient processing of auditory and tactile stimuli. The ERP data further suggest that a relative enhancement at perceptual processing stages contributes to the processing advantage for temporally attended stimuli. The existence of cross-modal effects of temporal attention underlines the importance of time as a feature for binding input across different modalities.