2 - The development of body representations

Summary

Body representations may be considered in terms of both their first- and third-person characteristics. By first-person, we mean those aspects of body awareness and knowledge that are typically exclusively available to the “owner” of the body – the self. By third-person, we mean those aspects of body awareness and knowledge that are at least potentially available to any observer. Although there is overlap between first- and third-person characteristics – I can observe my own hand movements as I type just as anyone who happens to be watching me type can also observe these movements – there are also some qualitatively distinct characteristics. Most importantly, the owner of the body gets various kinds of information in a qualitatively different form and in some sense “privately.” For example, the proprioceptive sense yields a type of first-person information that allows for awareness of one’s movement and the relative position of various parts of one’s body. Thus, even without visual information, it is possible to determine fairly accurately both dynamic and spatial aspects of one’s body parts through proprioception. And so, in the dark, I know a lot more about my body than you do.

At least in humans, however, bodies are represented simultaneously in terms of both first- and third-person characteristics. Bodies have both externally observable properties and internal conditions. As adults, our experience and representation of our own bodies, for the most part, consist of integrated multisensory input. That is, when we perform an arm movement, we do not perceive the visual and proprioceptive information as separate yet correlated, but instead as unified and integrated. Similarly, the observed movement of our faces when we look in a mirror is perceived in integration with felt movement of our face. This integration depends upon the perfect temporal coincidence of the relevant information. In illustration, we know that adults will misperceive a fake rubber hand as their own under conditions where they are presented with a tight temporal correlation between first person information (either tactile or proprioceptive) from their own real hand and “third person” visual information from the rubber hand (e.g. Botvinick and Cohen, 1998; Dummer et al., 2009).