Temporal determinants of a kinesthetic aftereffect.

Abstract

The development of a kinesthetic aftereffect as a function of stimulation times of IS, 30, 45, 60, 75, 90, 105, and 120 sec. and its dissipation after 30 and 90 sec. stimulation have been investigated in 2 experiments. The task required kinesthetic judgment of the horizontal following controlled rhythmic stimulation of the extended hand across a slanted bar. In Experiment I the aftereffect was shown to increase with stimulation time. In Experiment II the size of the aftereffect was similar immediately following 30 and 90 sec. stimulation but the rate of dissipation was greater for the shorter than for the longer stimulation. Since with the method of adjustment dissipation is rapid during the adjustment period, the development function of Experiment I is interpreted as representing a joint function of stimulation time and differential dissipation rates.

Confounding of psychophysical errors and sensory effects in adjustment measures of spatial aftereffects

“…The average of the counterbalanced measuresis taken as an estimate of the "true" AE (e.g., Gibson & Radner, 1937;Morant & Harris, 1965;Singer & Day, 1965, 1966. The validity of this technique depends upon a number of assumptions.…”

“…They used the objective target position (vertical) as the pretest and posttest SP. Some other experimenters have either followed the same procedure (e.g., Morant & Harris, 1965;Singer & Day, 1965) or have used an SP other than the target position in the pretest and posttest (e.g., Singer & Day, 1966). , Under these conditions, if no AE occurs there should be no shift in the judged target position from pretest to posttest and any objectively equal pretest and posttest SPs should be judged equal.…”

“…When adjustment methods are used to measure AEs, therefore, part of the shift in the PSV may be attributable to differences between adjustment errors in the pretests and posttests. The determinants of these errors of anticipation (undershooting) and habituation (overshooting) will be complicated by the fact that AEs dissipate rapidly at first (Hammer, 1949;Singer & Day, 1965;Ganz & Day, 1965;Sagara & Oyama, 1957;Wenderoth, 1967). Not only will the judged target position be different in the pretest and posttest but the judged posttest target position will be changing while the adjustment is being made.…”

The kinesthetic spatial aftereffect as a function of the angular displacement of the joints of the arm

“…An adjustable stool was used so that S's shoulder height could be adjusted to the height of the test bar. Each S was tested only once to eliminate the possible introduction of a learned effect (Collins & Singer,1967), a single posttest only was given and the time taken between cessation of stimulation and the completion of the posttest was recorded (Singer & Day, 1965).…”

Correlation between visual and kinesthetic spatial aftereffects.

“…aftereffects dissipate exponentially over time (Hammer, 1949;Oyama, 1953;Singer & Day, 1965) and, further, are most frequently investigated using the method of adjustment involving a timedelay aftercessation of stimulation, their magnitude will vary as a function of the time 5" takes to complete the adjustment. Lack of correlation between aftereffects in two modalities could, therefore, be attributable to differences in adjustment times.…”