Author:

Keywords:

Science & Technology, Social Sciences, Life Sciences & Biomedicine, Ophthalmology, Psychology, Psychology, Experimental, 1701 Psychology, 1702 Cognitive Sciences, Experimental Psychology, 5202 Biological psychology, 5204 Cognitive and computational psychology

Abstract:

Research into the organization of high-level visual cortex has mainly used discrete object classes (eg faces and buildings). In contrast, the lower levels of the visual cortex have also been studied using phase-encoding techniques with gradually changing rotating wedges and expanding/contracting rings. The gradual stimulus changes cause traveling waves on the cortical surface, and time delays of each cortical location are related to stimulus preference. We propose to extend this method to study higher-order properties of visual objects. We validated this method with a face/house morphing continuum. We also included contracting/expanding rings cut out from natural scenes. Face- and house-selective regions (fusiform face area or FFA; parahippocampal place area or PPA) were defined with traditional block-design localizers. The method worked as intended: activity in FFA corresponded to presentation of face(-like) stimuli, and activity in PPA corresponded to the presentation of building(-like) stimuli. Additionally, confirming existing literature with discrete object classes, activity in FFA and PPA was time-locked to the presentation of foveal and eccentric rings, respectively. The results, however, contradict large-scale continuous maps across the ventral visual stream. Nevertheless, the results show that phase-encoding techniques can be applied to stimuli with feature variations more suited to investigate high-level visual regions