Effect of Enhancement of Head Boundary on Head Size and Shape

Abstract

In a previous study an attempt was made to deal experimentally, from the viewpoint of sensory-tonic and developmental theory (3), with the problem area of self-perception, or more specifically, with the perception of one's own body or body parts (4). A fundamental assumption underlying the study was that the body serves a dual role. On the one hand, the body may serve as a frame of reference for determination of characteristics of objects in space; on the other, the body may in itself be regarded as an object. With regard to the latter aspect, one recognizes that the body has perceptual properties in common with all other objects, such as shape, size, location, etc. Under the assumption that object size is, in general, inversely affected by the degree of differentiation of the object from its surrounding framework, it was hypothesized that the degree of articulation of one's own body from environment would similarly affect perception of size of body parts. Degree of articulation of self from environment was experimentally manipulated by enhancing the boundary of the head through touching its borders. In keeping with expectation it was found that perceived head width decreased when the temples were touched. The present experiment extends the previous one in two ways. (a) It examines the effect of articulating head boundary on perceived self size by means other than touch. (b) It explores the effect-of articulation limited to parts of the head. This deals with shape changes insofar as an expected expansion or contraction of part of an object is equivalent to change in shape of the whole object. Three experiments were carried out dealing with the effect of enhancement of the boundary of one side of the face on perception of head size and shape. In the first experiment the boundary of one or the other side of the borders of the face was enhanced by touching; in the second experiment, articulation was accomplished by cold applied to one or the other side; and in the third experiment heat served as the stimulus making for differentiation of the boundary of the head. With the nose of S articulated by touching a rod located in the median sagittal plane it was hypothesized that: (a) enhancement of the boundary on one side would make for a smaller perceived distance between the nose and the articulated side of face than between the nose and the unarticulated side of face; and (b) the shrinkage in perceived distance between the nose and