In my “Living without proprioception” article, I briefly alluded to the terms of embodiment theory as proposed by Dr. Shaun Gallagher: body image and body schema. In this post, I want to clarify and expand on this incredibly useful conception distinction.
In the very first chapter of his book How the Body Shapes the Mind, Gallagher sets out to clearly define these two terms in such a way as to be useful to future researchers of the body and the mind. This task is not as easy as it sounds, simply because in the past, the two terms have often been conflated.
Gallagher’s proposal gives the following definitions:
-Body Image: a system of perceptions, attitudes, and beliefs pertaining to one’s own body.
-Body Schema: A system of sensory-motor capacities that function without awareness or the necessity of perceptual monitoring.
“So the difference between body image and body schema is like the difference between a perception(or conscious monitoring) of movement and the actual accomplishment of movement, respectively.”
The body image is a “reflexive intentional system”, that “normally represents the body as my own body, as a personal body that belongs to me.” whereas the body schema operates at a level “below self-referential intentionality”. It is a “preconscious, subpersonal process”.
…to the extent that I become perceptually aware of my body, as something in my peripheral field or as something attended to, then I have an occurrent body percept[image]. Although I may not be conscious of certain beliefs or attitudes that I have concerning my body, in principle I should be able to bring such beliefs and attitudes to consciousness. In contrast,…the body schema is always something in excess of that which I can be conscious. Even if I become conscious of certain aspects of my posture and movement, the body schema continues to function in a non-conscious way, maintaining balance and enabling movement.
Furthermore, there is considerable empirical support to this conceptual distinction. As discussed in a previous article, Ian Waterman stands as a case in which there is an intact body image without an functional body schema. On the opposite dissociative end, intact body schemas can be found without completely intact body images in the cases of unilateral neglect, where damage to one hemisphere of the brain(usually stroke), would cause the patient to neglect the contralateral perceptual field, while still having working motor programs for the neglected side. In his book, Gallagher presents much more empirical evidence in support of his distinction and it is for this reason that it has the potential to shape untold amounts of future research design methodology. In his words, “Many…methodological difficulties can be resolved only when, on the theoretical side, clear conceptual distinctions and definitions are provided.”