Fluctuations in Sustained Attention Modulate Learned Saccade Readiness

Individuals regularly fluctuate in their ability to focus attention as well as in their ability to spatially shift attention among different locations. However, the degree to which these ongoing changes in attentional states share common mechanisms or interact with one another remains unknown. In the current study, participants completed a modified gradual continuous performance task during which they monitored one of two lateralized streams of black and white images for the appearance of frequent target stimuli, withholding responses to foils. Periodically, a visual cue signaled participants to either maintain fixation at the current stream or to make a saccade to the opposing stream, and participants made a parity categorization for a digit appearing at the cued location. Trial-by-trial variation in pupil size, an indicator of arousal, accounted for both fluctuations in sustained attention and shift readiness but fluctuations in sustained attention were not associated with general modulations of shift readiness. Furthermore, we manipulated the frequency of attention shift cues over time and observed that unexpected shift cues were most disruptive, yielding longer saccade latencies, when participants lacked sustained focus. Our results suggest that ongoing changes in sustained attention occur independently from spatial shifting readiness but carry consequences for learned adjustments in saccade preparation.