Abstract
Visual perception of objects has been investigated traditionally using 2D images. Importantly, however, unlike images, real-world objects provide observers with the potential for manual interaction. In line with this distinction, recent behavioral and fMRI research indicates that real objects may be processed and represented differently to 2D images, although the mechanism for these effects remains unknown. Here, we compared electrophysiological brain responses for real objects with matched pictures to examine whether the underlying temporal dynamics of brain activation differed across the two display formats. We hypothesized that the real objects would be associated with stronger motor preparation signals in dorsal cortex than pictures. Using high-density EEG, occlusion spectacles, and a custom-built experimental apparatus, we recorded brain responses to visual stimuli consisting of 96 real-world graspable objects and 96 2D photographs of the same items printed in high-resolution. We found significant reductions of event-related power for real objects versus pictures over bilateral centro-parietal electrodes in the mu frequency band, consistent with enhanced motor preparation processes. Event-related potentials revealed an early occipital negativity for real-world objects versus images, consistent with stereo depth processing, and late parietal modulations likely reflecting object-recognition processes. Importantly, early occipital differences did not account for centro-parietal motor preparation effects. We conclude that the temporal dynamics of recruitment of sensorimotor regions in the dorsal stream are different for real objects than 2D pictures.
Meeting abstract presented at VSS 2018