The key to unlocking the virtual body: virtual reality in the treatment of obesity and eating disorders

Abstract

Obesity and eating disorders are usually considered unrelated problems with different causes. However, various studies identify unhealthful weight-control behaviors (fasting, vomiting, or laxative abuse), induced by a negative experience of the body, as the common antecedents of both obesity and eating disorders. But how might negative body image--common to most adolescents, not only to medical patients--be behind the development of obesity and eating disorders? In this paper, I review the "allocentric lock theory" of negative body image as the possible antecedent of both obesity and eating disorders. Evidence from psychology and neuroscience indicates that our bodily experience involves the integration of different sensory inputs within two different reference frames: egocentric (first-person experience) and allocentric (third-person experience). Even though functional relations between these two frames are usually limited, they influence each other during the interaction between long- and short-term memory processes in spatial cognition. If this process is impaired either through exogenous (e.g., stress) or endogenous causes, the egocentric sensory inputs are unable to update the contents of the stored allocentric representation of the body. In other words, these patients are locked in an allocentric (observer view) negative image of their body, which their sensory inputs are no longer able to update even after a demanding diet and a significant weight loss. This article discusses the possible role of virtual reality in addressing this problem within an integrated treatment approach based on the allocentric lock theory.

© 2011 Diabetes Technology Society.

Figures

Figure 1

Egocentric and allocentric representation of space. The egocentric representation (on the left-hand side; image taken from the first-person shooter video game Crysis) integrates perceptual impressions gathered from a first-person perspective relative to the position and heading (front–back, right–left, and up–down) of the subject. In this representation, the world constantly changes while the navigator remains spatially fixed in the center of the reference system. The allocentric representation (on the right-hand side; image taken from the Pac-Man video game) instead establishes a “map” with an origin and a reference direction external to the subject. In this representation the world remains stationary while the subject moves inside it.

Figure 2

Field and observer modes in episodic memory. In field mode, the subject remembers the view of the Shenandoah Valley from his hiking experience through the subject’s own eyes, as if he were looking outward (on the left-hand side). In the observer mode, the subject remembers the view of the Shenandoah Valley including him as an actor in the memory image (on the right-hand side).