Abstract
Recent behavioral evidence suggests that object representations more strongly constrain attention when spatial location of the target is uncertain, making a direct prediction that spatial uncertainty should modulate the strength of object representations (Shomstein, Zhang, & Dubbelde, 2022). This prediction, however, is counter to the established ‘binding’ theories of attention postulating that binding an object’s features necessitates selecting its location. Here, we test this prediction that the strength of object representation is higher under high uncertainty conditions. We obtained fMRI data and focused on changes in neural activity patterns in object-selective lateral occipital complex (LOC), spatial-selective intraparietal sulcus (IPS), and early visual cortex (EVC), as a function of spatial uncertainty. On each trial, one vertically-shaped object was presented at the center of the screen. Two target Gabor patches were superimposed respectively over the central fixation and one peripheral end of the object. Participants reported whether the patches’ orientations matched. The uncertainty of the peripheral Gabor patch location was manipulated: (1) high uncertainty - target appeared 50% on either end of the object; (2) low uncertainty - target appeared 75% on one end. Using multivoxel pattern analysis, we found that while completely task-irrelevant, object identities could be decoded significantly above chance in EVC. Critically, and as predicted, this decoding accuracy was higher in high spatial uncertainty compared to low uncertainty condition. This finding runs counter to ‘binding’ theories positing that spatial attention automatically “glues” and facilitates object representations; rather, explicit spatial attention guidance resulted in weaker object representations. This discrepancy, likely coming from the task-irrelevant nature of objects in our study, suggests that the automaticity of attentional binding has to be reevaluated. Current models of attention should be revised to incorporate contributions from task-irrelevant aspects of the environment which may dynamically interact with the ongoing cognitive selection processes.