Abstract
A salient, but irrelevant singleton can capture attention independent of task goals. However, attention capture effects appear to be less consistent when an observer is concurrently engaged in a competing working memory task (e.g., Boot et al., 2005). Under a high working memory load (WML), different types of unique singletons have been shown to both exacerbate (color singleton) and eliminate (onset singleton) attention capture effects as measured by response time (RT). These conflicting findings relied on a comparison of static and dynamic singletons, and may be attributable to the unique temporal dynamics of these two singletons classes. In the current studies, we evaluated whether another type of dynamic singleton, looming motion, would capture attention under a high WML. Unlike an onset stimulus, the looming singleton status continues beyond a single frame, similar to a persisting color singleton. In Experiment 1, participants searched for a target object with a looming singleton, where the target was the looming singleton at chance. Concurrent WML was manipulated by having participants maintain a digit string (1 or 6 digits) in memory. After the search trial, participants responded to the absence/presence of a single digit in the previously presented digit string. We found that RTs were faster when the target loomed under high WML, but there was no additive cost for looming distractors. It is possible participants may have prioritized looming objects by restricting their attentional set to dynamic events. We tested this possibility in our Experiment 2 by adjusting our target to be a color singleton. As such, participants only needed to monitor for a static, color singleton. RT differences between looming targets and distractors were mitigated under the high WML. We interpret these results as evidence that a concurrent WML can delay the deployment of selective attention processes for dynamic, irrelevant singletons.