Changes in Position of Presentation as Related to Perceptual Efficiency in Stimulus Identification

Little experimentation has been undertaken in the area of perception of variously positioned geometrical figures. One study concerning symmetrical figures has been reported by Ganguli (1). He investigated the problem of determination of the optimal break in a circle which will be perceived as a whole through closure tendency. The incomplete circles in his experiment ranged from openings of 0° to 45°. Individual differences were found in threshold which varied as a function of the position of the gap. Threshold values were greater for lower gapped positions than for upper gapped positions. In a more recent study by Postman and Bruner (3), closure is studied as affected by set and response habit of S. The purpose of their experiment was to observe the effect of differences in past experience with closed and open circles on the readiness with which closure takes place when incomplete circles are presented under low level stimulation. Set and past experience were observed to affect the operation of closure. However, a possible extraneous effect of gap positioning on perception apparently was not controlled systematically in their study. It is possible that failure to control gap position may have weakened the experimental effects observed