ABSTRACT
A concern for estimates of linear extent arises in many contexts, including basic research in perception (e.g., judgments of distance), clinical studies (e.g., judgments of “body image”) and industry. From an ecological perspective, size and distance are most meaningful in terms of body-scaled potential activities. Natural selection and everyday activities guarantee that humans are able to judge linear extents under many conditions with sufficient accuracy to support a great variety of actions. For perception to serve action, distance and size must be perceived in body-scaled terms, and to do this we must be able to accurately judge limb lengths, maximum body width, and other aspects of body size. In apparent contradiction of this expectation stands a sizeable literature suggesting that many people grossly mis-perceive their body size. This literature on “body-image” is fraught with problems, including questionable measurement techniques, and rarely includes comparison of accuracy in body image with that of other objects (Schlundt & Johnson, 1990; Thompson, 1996).
