Abstract
Rhythmic patterns in our environment, such as music or speech, can flexibly induce temporal expectations. Such rhythmic facilitation gives rise to enhanced perceptual processing by means of temporal orienting of attention and foreperiod effects. So far, the benefits of temporal expectations have only been described within task designs in which individuals perform discrete tasks on a trial-by-trial basis. The current study is designed to investigate how temporal expectations are formulated dynamically during an ongoing Continuous Performance Task (CPT) with an implemented rhythmic structure. By using this ongoing task design, we were also able to investigate whether the lack of a rhythmic structure leads the cognitive system to adjust to operate in temporal uncertainty. A new CPT variation was designed to allow the estimation of parameters derived from the Theory of Visual Attention (TVA), a mathematical model which provides a comprehensive account of attention-related processes. Participants monitored a continuous stream of arrow-shaped targets that appeared for varying durations (10-80ms) and were followed by a mask. During the interstimulus intervals, they were requested to indicate the direction of each arrow (if they had managed to identify it) and pupillometry data was recorded. The interstimulus intervals were manipulated so that targets appeared in either an isosynchronous rhythm or unpredictably within a random temporal structure. In accordance with previous reports, temporal expectations improved the visual processing speed TVA parameter. Strikingly, random temporal structures also conferred a unique benefit, yielding a lower perceptual threshold according to TVA. Therefore, while temporal predictions facilitate efficient visual processing, increasing the temporal uncertainty promotes higher perceptual sensitivity. The behavioural observations were correlated with dynamic shifts in pupil dilation, showing phasic increases before predictable onsets and overall expansion in temporal uncertainty. The results indicate a dynamic adaptation of attention in accordance with the temporal structure to maximize performance.
Meeting abstract presented at VSS 2018