ABSTRACT
The major aspects of the theory presented here have been noted previously (Gogel, 1974). Essentially, it consists of five factors. These are (a) Emmert's law, (b) the equidistance tendency, (c) the egocentric reference distance, (d) the binocular disparity cue of perceived depth, and (e) the role of off-sized perceptions in direct responses to distance. Factors b, c, and e are labeled as. heuristic. This term is meant to indicate a contribution to the perception or response that, at least partially, is determined by processes internal to the observer rather than being specified solely by sensory information (also see Braunstein, 1976). The heuristic factors are expected to increase their contribution to the perception or response as the sensory information is reduced or eliminated. In summary, the theory states that the equidistance tendency, together perhaps with binocular disparity when available, mainly determines the perceived distance of the horizon moon, whereas the egocentric reference distance mainly determines the perceived distance of the zenith moon. It is asserted that the perceived size of the moon is then specified by these perceived distances consistent with the SDIH and with Emmert's law. The reported distance of the horizon moon, however, sometimes is cognitively determined as a result of the judgment that the moon at the horizon is a large, off-sized object relative to the moon at the zenith. The perception of the size and distance of the horizon moon, however, despite the cognitive aspect of the distance response remains consistent with the SDIH and consistent with Emmert's perceptual law.
