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Catherine Reed, Alison Harris, Madison Lodge, Grant Gaither; Segmentation of the Human Body: How Does the Visual System Define Body Parts?. Journal of Vision 2017;17(10):1254. doi: 10.1167/17.10.1254.
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How does the visual system define and segment the parts of the body? Although previous work suggests people categorize human body parts based on functional units that can be coordinated to perform actions, less research has focused on how body parts are defined within the long-term visuospatial body representation. Recent data on holistic body processing has shown that the visual system discriminates postures of upper body parts better than lower body parts, and local body-part configurations are processed together. However, neither study explicitly tested which body-part divisions were most salient. Here we examined how the visual system naturally segments the body schema into parts in two experiments. In Experiment 1 (n=23), participants were shown a human body in a neutral posture and determined whether two dots were on the same or different body parts. Body stimuli included front and back views of the body at 0° and 90° orientations. Equidistant dots were placed within a body segment (e.g., within the forearm), across a joint but within a body part (e.g., forearm and upper arm), and across body parts (e.g., torso and upper arm). Regardless of orientation and view, participants judged body segments separated by joints as different body parts. In Experiment 2 (n=30), we investigated whether body-part distinctions influenced distance judgments within the context of the body. In a successive matching task, participants determined whether two dots placed on neutral body postures were the separated by the same distance. Discrimination was generally better and faster for upper over lower body regions. Additionally, participants showed increased speed and accuracy for dots crossing parts compared to dots within a part, suggesting that the salience of part divisions influenced perception of the dots' locations. These results confirm that the spatial body representation is 3D, not-orientation specific, and salient part divisions define its topography.
Meeting abstract presented at VSS 2017
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