Sensitivity to stimulus similarity is associated with greater sustained attention ability

Sustained attention is critical for tasks where perceptual information must be continuously processed, like reading or driving; however, the cognitive processes underlying sustained attention remain incompletely characterized. In the experiments that follow, we explore the relationship between sustaining attention and the contents and maintenance of task-relevant features in an attentional template. Specifically, we administered the gradual onset continuous performance task (gradCPT), a sensitive measure of sustained attention, to a large web-based sample (N>20,000) and a smaller laboratory sample for validation and extension. The gradCPT requires participants to respond to most stimuli (city scenes - 90 %) and withhold to rare target images (mountain scenes - 10 %). By using stimulus similarity to probe the representational content of task-relevant features-assuming either exemplar- or category-based feature matching-we predicted that RTs for city stimuli that were more "mountain-like" would be slower and "city-like" mountain stimuli would elicit more erroneous presses. We found that exemplar-based target-nontarget (T-N) similarity predicted both RTs and erroneous button presses, suggesting a stimulus-specific feature matching process was adopted. Importantly, individual differences in the degree of sensitivity to these similarity measures correlated with conventional measures of attentional ability on the gradCPT as well as another CPT that is perceptually less demanding. In other words, individuals with greater sustained attention ability (assessed by two tasks) were more likely to be influenced by stimulus similarity on the gradCPT. These results suggest that sustained attention facilitates the construction and maintenance of an attentional template that is optimal for a given task.