Structural Encoding of Body and Face in Human Infants and Adults

Abstract

Abstract& Most studies on visual perception of human beings have focused on perception of faces. However, bodies are another important visual element, which help us to identify a member of our species in the visual scene. In order to study whether similar configural information processing is used in body and face perception, we recorded high-density evenrelated potentials (ERPs) to normal and distorted faces and bodies in adults and 3-month-old infants. In adults, the N1 responses evoked by bodies and faces were similar in amplitude but differed slightly in latency. The voltage topography of N1 also differed in concordance with fMRI data showing that two distinct areas are involved in face and body perception.Distortion affected ERPs to faces and bodies similarly from N1 on, although the effect was significant earlier for bodies than for faces. These results suggest that fast processing of configural information is not specific to faces but it also occurs for bodies. In 3-month-old infants, distortion decreased the amplitude of P400 around 450 msec, showing no interaction with image category. This result demonstrates that infants are not only able to recognize the normal configuration of faces, but also that of bodies. This could either be related to an innate knowledge of this particular type of biological object, or to fast learning through intense exposure during the first months of life. &

Faces, Bodies, Social Vision as Agent Vision, and Social Consciousness

“…In keeping with these results, behavioral data (Slaughter, Stone, & Reed, 2004) have recently been obtained showing sensitivity for the canonical properties of faces and bodies alike at around 18 months. These results are supported by ERP recordings providing evidence that the configuration of faces and bodies is already processed at thrre months of age (Gliga & Dehaene-Lambertz, 2005).…”

“…Besides emphasizing the close relationship between processing of facial and bodily expressions, these findings additionally suggest that emotional expressions in both faces and bodies are encoded within a very early stage of processing, even before the visual categorization of a stimulus as a face or a body and the recognition of the personal identity has taken place, as indexed by the time course of the N170/M170 component (Bentin et al, 1996;Eimer, 2000b;Gliga & Dehaene-Lambertz, 2005;Kloth et al, 2006;Liu, Harris, & Kanwisher, 2002;Stekelenburg & de Gelder, 2004;Thierry et al, 2006). In fact, faces or bodies that were presented in isolation as control conditions did not elicit early emotion effects on the P1-component.…”

“…The N170 is a well-known negative ERP-component, peaking around 170 ms at occipito-temporal sites, and is often linked to the stage of the structural encoding of faces (Bentin, Allison, Puce, Perez, & et al, 1996;Bruce & Young, 1986;Eimer, 2000b). Yet this component is also elicited by images of whole bodies (Gliga & Dehaene-Lambertz, 2005;Meeren, van Heijnsbergen, & de Gelder, 2005;Stekelenburg & de Gelder, 2004;Thierry et al, 2006). Most importantly, the electrophysiological inversion effect (Eimer, 2000a;Itier & Taylor, 2002;Watanabe, Kakigi, & Puce, 2003), consisting of a delayed and enhanced N170 deflection for inverted stimulus presentation, was elicited by both faces and bodies in contrast to control objects (Stekelenburg & de Gelder, 2004).…”

Infants perceive human point-light displays as solid forms

“…To our knowledge this study is the first to demonstrate infants' application of the solidity principle to human point-light displays, and is one of the first to demonstrate sensitivity to the violation of the solidity of an object or human when this occurs in full view of the infant rather than behind an occluder. Furthermore, previous studies looking at infants' sensitivity to violations of whole body representations of humans have only violated the form by moving the location of the arms and legs (Slaughter, Heron & Simm, 2002;Gliga & Dehaene-Lambertz, 2005).…”

“…Another study, however, suggests that infants may encode aspects of the human form much earlier. Specifically, infants at three months show differential brain activity (ERPs) to scrambled pictures of headless bodies when a leg is moved to the head's location (Gliga & Dehaene-Lambertz, 2005). It may be that, while Infants perceive human point-light displays as solid forms, page 4 infants do not have access to an explicit pictorial representation of the human form before 18 months, younger infants may have access to implicit representations, at least of parts of bodies, which allow them to make sense of others' movements and intentions.…”