On the relation between induced and residual kinesthetic after-effects.

Abstract

Retention of figural after-effects over varying periods of time has been reported by a number of investigators (Gibson, 1933; Koehler 8: Wallach, 1944; Koehler & Dinnerstein, 1947; Koehler & Fishback, 1950; Gardner, 1961; Wertheimer & Leventhal, 1958). T he existence of residual after-effects suggests an analogy with retention of learned material. If amount of material retained is related to amount of material learned, then it is meaningful to ask whether in the after-effect situation, the amount of retained or residual afcer-effect is related to the size of the afcer-effect induced earlier. The present study was designed to determine whether there exists a relationship between the size of an induced kinesthetic after-effect and the size of [he residual after-effect. METHOD Appauatas.-The apparatus consisted of three wooden blocks: (1 ) a scandard block 1.5 in. wide, 60 in. long, and 2 in. thick; (2) a tapered block, 60 in. long, and 2 in. thick, varying in width from 1 in. to 2% in. and changing at the rate of 1/32 in. per inch, and (3) an inspection-block, 0.5 in. wide, 24 in. long, and 2 in. thick. The three blocks were mounted on tables 36 in. high and parallel to each other. The standard block and the inspection-block were at the side of S's non-preferred hand and the tapered variable-width block was at the side of S's preferred hand. The tapered block was fitted with an H-shaped rider within which S placed his thumb and forefinger while making equality judgments. Procedare.-The apparatus was used to obtain measures of the apparent widch of the standard block. S was to find a widch between the thumb and forefinger on the tapered block which felt equal to the width of the standard block held in the other hand. The measure of point of subjective equality (PSE) was the mean of four judgments made alternately from points 1.25 in. wide or 1.75 in. wide. An inspection-period interposed between two measures of PSE allowed for a measure of the kinesthetic after-effect. During inspection S, while holding the inspection-block between the thumb and forefinger of his nonpreferred hand, moved the hand back and forth along the block at a prescribed rate and for a prescribed time. The other hand was held flat on a table. The difference between the pre-inspection PSE and the post-inspection PSE constitutes the measure of the kinesthetic after-effect. Ss were blindfolded while making judgments and during the inspeccion-period.