Body inversion effect without body sense: insights from deafferentation

Like faces, human bodies are recognized via the configuration of their parts; their recognition is impaired by inversion. Processing of configural relations has been shown to depend on perceptual expertise with certain classes of objects. Because people see their own body and others' bodies frequently, humans are experts in the visual processing of human body postures. In addition, the observer's own on-line, multimodal body representation which heavily relies on current proprioception may play a crucial role in recognizing human body postures. We investigated whether static body posture recognition relied on current proprioceptive inputs or whether visual familiarity and stored body representations were sufficient. IW, who is deafferented (lost cutaneous touch and proprioception from his body), was tested on the recognition of upright and inverted human body postures, faces, and houses. As controls, IW showed an inversion effect for abstract, common, and rare human body postures as well as faces, but not houses. Results rule out a strong contribution of current afferent inputs to the recognition of human postures. The findings are discussed in terms of the role of the body schema in body posture recognition and how other contributions from one's own body may be involved in the visual processing of human bodies.