Abstract
Faces are particularly well suited to recruit holistic processing, whereas other classes of objects recruit more feature-based processing. Sequential presentation of features disrupts the perception of second-order relations and therefore disrupts holistic processing. One way of presenting features sequentially is with aperture viewing, where subjects view the object through a small, moveable aperture. Here, we compared BOLD fMRI measurements during aperture viewing and normal (whole) viewing of faces, Greebles, and buildings to test the effect of sequential feature-based presentation on activation in the FFA and other areas of visual cortex. Neuroimaging and neuropsychological studies have linked holistic processing with a face-selective region of cortex in the fusiform gyrus called the fusiform face area (FFA). However, contrary to our prediction based on this evidence, the FFA showed more activation with aperture viewing than whole viewing, suggesting that the FFA may not be recruited solely or specifically for holistic processing. The superior temporal sulcus (STS), which is another face-selective region, showed a different pattern of activation than the FFA, in which activation decreased while subjects were actively exploring the stimulus, then increased at the termination of the trial. Early visual cortex showed a third distinct pattern, which was sustained deactivation below fixation baseline. This pattern may be due to the influence of aperture viewing on the spatial allocation of attentional resources. The results are discussed in terms of the spatial and temporal integration processes required to successfully recognize objects under aperture viewing conditions.
This research was supported in part by the Indiana METACyt Initiative of Indiana University, funded in part through a major grant from the Lilly Endowment, Inc.