Influence of Repeated Testing and of Starting Position in Kinesthetic Aftereffect

Abstract

The purposes of this experiment on kinesthetic aftereffects were to determine whether test (T) trials inserted between inspection (I) periods affected the magnitude of effect and to examine the influence of wedge starting position on single judgment and cumulative effect on averaged judgments using the method of average error. 60 experimental Ss had 1-min. I periods separated by rests or by T trials. A control group had T trials without I periods. Each S had 4 trials per test period and started each trial at a different wedge position (A, B, C., or D). Starting position order was varied within groups (ADCB, BADC, CDAB, or DABC). Results indicate: (a) T trials may decrease aftereffect; (b) starting position highly influences single PSE choice; and (c) effects of starting position are not a simple function of starting position per trial since the impact of each start is modified by the first in a series. Therefore, averaging settings made on the basis of starting positions above and below POE does not eliminate the bias created by the initial starting position.