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Jonathan S. Cant; Exploring the processing of the shape and material properties of scenes and objects in human visual cortex. Journal of Vision 2014;14(10):1091. doi: 10.1167/14.10.1091.
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© ARVO (1962-2015); The Authors (2016-present)
Recently, I demonstrated that the scene-sensitive PPA is more active for judgments of the material properties of objects (whether an object is made of soft or hard material; Cant & Goodale, 2011), compared to judgments of object shape. This appears inconsistent with the view that PPA is specialized for processing scenes, since the single objects used did not invoke scene imagery. But material-property judgments are important in scene processing as they can affect the strategies used to recognize and navigate through an environment (e.g., soft/hard terrain affects the posture and stability used to navigate through a scene). Thus, the material-property task used previously may have invoked a type of processing in PPA that is distinct from its role in processing the geometry of scenes. Specifically, these findings suggest that PPA represents scenes by processing both spatial (shape) and non-spatial (material) visual features. To investigate this possibility, I used fMRI to examine activity in PPA while participants made shape and material-property judgments of both objects and scenes (images consisted of a central object located within an indoor scene). I also examined activity in LOC, to explore if this object shape-sensitive region is also involved in processing the shape of scenes. Interestingly, judgments of object shape produced the highest activation in LOC (compared with judgments of scene shape, scene material, and object material, which did not differ), demonstrating that LOC is not a general-purpose shape-processing region. In PPA, activation was higher for judgments of object material compared with object shape, replicating previous results. But importantly, activation for both shape and material judgments of scenes was higher than activation for judgments of object features. This demonstrates that PPA does indeed process both spatial and non-spatial visual features, but importantly, this processing is specialized for visual features of scenes, not single objects.
Meeting abstract presented at VSS 2014
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