A delay in sampling information from temporally autocorrelated visual stimuli

Much of our world changes smoothly in time, yet the allocation of attention is typically studied with sudden changes - transients. When stimuli change gradually there is a sizeable lag between when a cue is presented and when an object is sampled (Carlson, Hogendoorn, & Verstraten, 2006; Sheth, Nijhawan & Shimojo, 2000). Yet this lag is not seen with rapid serial visual presentation (RSVP) stimuli where temporally uncorrelated stimuli are presented (Vul, Kanwisher & Nieuwenstein 2008; Goodbourn & Holcombe, 2015). These findings collectively suggest that temporal autocorrelation of a feature paradoxically increases the latency at which information is sampled. This hypothesis was tested by comparing stimuli changing smoothly in time (autocorrelated) to stimuli that change randomly. Participants attempted to report the color coincident with a visual cue. The result was a smaller selection lag for the randomly varying condition relative to the condition with a smooth color trajectory. Our third experiment finds that the increase in selection latency is due to the smoothness of the color change after the cue rather than extrapolated predictions based on the color changes presented before the cue. Together, these results support a theory of attentional drag, whereby attention remains engaged at a location longer when features are changing smoothly. A computational model provides insights into neural mechanisms that might underlie the effect.