Behavioral and neural signatures of object-based attention in the human visual system

How might one demonstrate the existence of an object representation in the visual system? Does objecthood arise preattentively, attentively, or via a confluence of bottom-up and top-down processes? Our fMRI work reveals that orientation-defined figures are represented by enhanced neural activity in the early visual system. We observe enhanced fMRI responses in the lateral geniculate nucleus and V1, even for unattended figures, implying that core aspects of scene segmentation arise from automatic perceptual processes. In related work, we find compelling evidence of object completion in early visual areas. fMRI response patterns to partially occluded object images resemble those evoked by unoccluded objects, with comparable effects of pattern completion found for unattended and attended objects. However, in other instances, we find powerful effects of top-down attention. When participants must attend to one of two overlapping objects (e.g., face vs. house), activity patterns from V1 through inferotemporal cortex are biased in favor of the covertly attended object, with functional coupling of the strength of object-specific modulation found across brain areas. Finally, we have developed a novel eye-tracking paradigm to predict the focus of object-based attention while observers view two dynamically moving objects that mostly overlap. Estimates of the precision of gaze following suggest that observers can entirely filter out the complex motion signals arising from the task-irrelevant object. To conclude, I will discuss whether current AI models can adequately account for these behavioral and neural properties of object-based attention, and what additional measures may be needed to realize more human-like object processing.