Ryan Miller¹, Blaire Dube¹; ¹Memorial University of Newfoundland

Representations in visual working memory (VWM) can be distorted by irrelevant perceptual information when the items share a feature dimension. When tasked with remembering the orientation of a rotated bar across a delay, for instance, exposure to an irrelevant, differently oriented bar during the delay causes a subtle shift in the remembered orientation towards the distractor orientation. This attractive bias is robust, but can be attenuated when delay-period perceptual input is memory-relevant (e.g., when the orientation of the second bar must also be encoded). Such attenuation of attractive bias has been demonstrated when single-feature items are encoded sequentially, and therefore share a single relevant feature dimension. Are VWM representations also distorted by a shared but irrelevant feature of a delay-period item when another of its features (e.g., its colour or location) must be encoded? In Experiment 1, two differently oriented bars were presented sequentially and participants reported the orientation of both; results replicated previous work showing no attractive bias in the reports of the initially encoded item. In Experiment 2, two differently oriented bars were again presented sequentially, but the second oriented bar appeared in a random location on the screen and participants were instructed to remember only its spatial position and ignore its orientation. Reports of the first orientation exhibited attractive bias toward the irrelevant orientation of the second memory item. Remembering a feature other than the orientation of the second bar fails to attenuate attractive bias, suggesting that robust distractor interference can be driven by an irrelevant dimension of an otherwise memory-relevant stimulus. A single delay-period item can serve as a memory target while simultaneously exerting distractor-specific biasing effects on an existing item in VWM.