PMC

Comparison between the body schema and the attention schema. (A) The body schema is a bundle of information that represents the physical body and that leads to better control of the body, better understanding of the body configurations of other people, and cognitive beliefs and linguistic claims about one’s own body. (B) The attention schema is a bundle of information that represents attention and has similar consequences as the body schema.

Examples of model-based control. (A) To enter a car without hitting your head requires the body schema to include an accurate model of the shape of your head. Women who wore feathered hats would develop an altered body schema to incorporate the hat, and would avoid hitting the feathers (). (B) The body schema depends on visual and somatosensory input, among other sources of information. Somatosensory input, however, is less accurate than visual. If you put your left hand under the table and leave it for a few minutes, the body schema begins to lose a precise representation of arm position. It is then difficult to point with the right hand, on top of the table, to the exact location of the left hand. (C) If the hand is perturbed from point 1 to point 2, but the body schema does not register that change, reaching becomes inaccurate. In this case, the real position is closer to the cup than the position registered by the body schema. The result will be an overreach that may knock over the cup. (D) In some cases the body schema loses specificity. The position of the arm is not precisely represented. In that case maintaining a steady arm position is difficult, especially in the face of external, perturbing forces, and reaching accurately is no longer possible.

(A) Subset of LUT entries of an example automaton that prescribe state transitions to on (1); white (black) states are 0 (1). (B) Wildcard schema redescription; wildcards denoted also by grey states. Schema is highlighted to identify the subset of LUT entries it redescribes. (C) Two-symbol schema redescription, using the additional position-free symbol; the entire set is compressed into a single two-symbol schema: . Any permutation of the inputs marked with the position-free symbol in results in a schema in . Note that redescribes the entire set of entries with transition to on and thus . Since there is only one set of marked inputs, the position-free symbol does not require an index. Although this figure depicts only the schemata obtained for the subset of LUT entries of that transition to on, entries that do not match any of these schemata transition to off (since is a Boolean automaton).

LLA and HC performance on the different body representation tasks. Notes. LLA=Lower limb amputees; HC= healthy controls; BS= body schema; NA= non-action oriented body representation.