Abstract
Mounting evidence suggests that object semantic knowledge influences our perception. However, the mechanism of semantic influences on perception remains unclear. It has been shown that physical context biases perception of objects. For example, object processing can be biased to the dorsal (action related) or ventral (identification related) visual processing streams by manipulating hand location in relation to the object. If one’s hands are proximal to the object, processing is biased toward the dorsal stream and if the hands are distal from the object, processing is biased toward the ventral stream. We investigated whether this perceptual bias becomes associated with object identity such that tools (e.g., hammer, wrench, saw), frequently perceived near the hands, bias the dorsal stream and non-tools (e.g., house, window, hydrant), infrequently seen near the hands, bias the ventral stream, regardless of the physical context. We used a detection task in which objects (controlled for low-level features such as clutter and luminance), were briefly presented near fixation. Participants performed one of two tasks, each designed to exploit sensitivity of the two streams: (i) detecting object flickering, because the dorsal stream has higher temporal resolution, and (ii) detecting a small gap in the object outline, because the ventral stream has higher spatial resolution. A significant interaction between object group and target type was observed, such that non-tools had lower RTs and higher accuracies for the spatial gap than the tools and this difference collapsed in the flickering condition. Importantly, inverting the objects, thereby reducing their semantic content, removes this interaction. This suggests that the differential processing in the two streams is driven by semantic knowledge of objects, rather than low-level differences. These results support the hypothesis that object semantic knowledge, derived from experiential hand proximity, biases visual processing to the dorsal or ventral stream.
Acknowledgement: NSF BCS-1534823 to S.S.