Abstract
Extensive research has shown that people are sensitive to statistical regularities of visual stimuli, such as a repeated sequence of target locations. To date, sequence learning of target locations has primarily been investigated in relatively simple scenarios involving a single object appearing in isolation. Many daily activities, however, require people to search for a target object from complex environments. To understand how repeated sequences of object locations are used in daily activities, we tested whether sequence learning also manifested in complex displays. Using variants of the serial reaction time (SRT) task, we asked participants to report the screen quadrant of a letter T, whose location followed a 12-trial sequence that repeated 30 times over 360 trials. Across different experiments, we manipulated the nature of distractors surrounding the target. The T could appear in isolation, as a color singleton among distractors with fixed or variable locations, or as a conjunction search target. Sequence learning, manifested as elevated response time when the learned sequence was disrupted, decreased in strength as spatial noise increased. Learning was robust when the T appeared in isolation or when it was surrounded by distractors that did not change locations across trials. It was reduced in a feature search task and eliminated in a conjunction search task. We further showed that after successful acquisition of sequence learning using unvarying distractors, changes in the distractor locations could disrupt sequence learning, even though the target sequence was maintained. This finding is consistent with the relational encoding account, suggesting that the target locations are coded in relation to concurrently presented distractors. Variability in distractor locations disrupts target sequence learning, revealing a limit in people’s ability to extract and use spatiotemporal regularities in complex visual environments.