ANORTHOSCOPIC FIGURE PERCEPTION: THE ROLE OF RETINAL PAINTING PRODUCED BY OBSERVER EYE MOTIONS (PARKS' EFFECT, APERTURE VIEWING).

摘要

When a figure is moved across a narrow slit which allows only a thin slice of it to be visible at any moment, a percept of the total figure can result. This phenomenon, described and labelled "anorthoscopic perception" by Zollner in 1862 and rediscovered by T. E. Parks in 1965, has been variously explained as (1) a consequence of the post-retinal storage of visual information, (2) the outcome of a cognitive-constructive process, or (3) the consequence of retinal painting produced by observer tracking eye motions. The painting explanation, while disputed, has been widely accepted by contemporary investigators.;It is argued from these and other data presented that two processes contribute to anorthoscopic perception--a post-retinal constructive process favored by low stimulus velocities and wider slits, and a painting process favored by high stimulus velocities and narrower slits. It is further argued that as the data reported suggests that even when painting is necessary for anorthoscopic perception, the post-retinal process is active, with painting serving to provide the post-retinal process with information that is otherwise poor or unavailable. Certain characteristic distortions occurring in anorthoscopic percepts are interpreted in the context of this dual process model, and an attempt is made to reconcile the data reported with the findings of previous investigators.;Experiments are reported in which retinal stabilization was employed to eliminate the possibility of painting due to observer eye motions, as observers watched figures crossing an electronically simulated slit on a CRT screen. With slit widths from 14.27' to 3.57' and 2(DEGREES) wide figures, it was found that with slow velocities (2(DEGREES) sec.) stabilization did not prevent anorthoscopic perception or impede the onset or stability of anorthoscopic percepts. Moreover, causing observers to track a point locked to the motion of a slowly moving figure in order to maximize painting reduced rather than facilitated figure perception. However, when figure velocities were increased a progressive dependence on painting developed, and at relatively high figure velocities (6 to 12(DEGREES)/sec., depending on the figure), figure perception became difficult or impossible in the absence of painting. Finally, as the velocity of an asymmetric figure was increased while subjects tracked counterphase to the figure's motion, a transition from a veridically oriented percept to a reversed percept (attributable to painting) occurred, with this transition occurring at a lower velocity with a narrow slit than with a wider slit.