Difference between revisions of "Tactile Motion Aftereffect"
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'''Wohlgemuth (1911):'''Removed the stimulus from the arm after motion. No after-effect reported.
'''Wohlgemuth (1911):''' Removed the stimulus from the arm after motion. No after-effect reported.
Revision as of 21:17, 8 February 2010
Wohlgemuth (1911): Removed the stimulus from the arm after motion. No after-effect reported.
Thalman (1922): The final stimulus that Thalman settles on as best for eliciting a tMAE, described in Expts 7&8 is "a coarsely corrugated muslin cloth" with "small pieces of cloth 2cm wide at separations of 4cm across the belt" sewed on, and is otherwise the same as what is described in Expts 5&6: "A rest, supporting the arm at the hand and elbow, was built over one of the drums at an angle of about 45 degrees, so that the rotating belt could be raised or lowered by means of a movable table pivoted at the lower end of the rest, and contact with the arm could thus be made or broken."
The belt was 12cm wide, Two adaptation speeds were used, 39cm/s and 109cm/s, which were found to be the better speeds from earlier expts. In expt 7 contact was broken after adaptation, in expt 8 it was maintained and was better for eliciting the MAE.
The direction and path of motion as well as the specific stimulus material changed (these factors are confounded with eachother). Before expts 5&6, the motion was across the arm, expt 5 onwards, it was along the arm. In expts 7&8, the direction of movement was from wrist to elbow, expts 5 & 6 used the opposite.
Expt 5&6 used rough corduroy and found it quite poor for eliciting the aftereffect, but is interesting because people experienced motion reversals in these expts - "It was not unusual for the Os to report that the direction had fluctuated 3 or 4 times during the course of a single stimulation."
One odd thing about Thalman is he never mentions a positive MAE, in all his experiments. I wonder if he just didn't report it because it was not the measure of interest - but that seems weird given the descriptions he is willing to indulge in so maybe he really got none, which makes me wonder about demand characteristics.
Expt 9 also tested the calf, with movement from knee to foot. Only one subject, results only briefly reported (no numbers given): "The results of the previous experiments were confirmed. Negative after-images were again reported. As far as T was able to discern, the after-effect on the leg was as pronounced as that upon the fore-arm."
Hazlewood (1971): 10 reports of an aftereffect out of a possible 100. Only one of those was unprompted, 4 were in the positive (unexpected) direction. “The tactile motion aftereffect, if it occurs at all, is very slight and requires conditions markedly different from those causing the visual motion aftereffect.” – p62 (Hazlewood, 1971)
Hollins & Favorov (1994): Drum with square wave surface - reliable tMAE (73-98%) but reported in both positive and negative directions. MAE duration increased linearly with adaptation duration.
Lerner & Craig (2002): Both Optacon and drum – less reliable (~50%) reports of any MAE, mix of positive and negative when present.
Watanabe et al. (2007): Reliable tMAE using Optacon-like stimulus (apparent motion) – adaptation biased perceived direction of ambiguous stimulus.
Planetta & Servos (2008): tMAE reported on about half of the trials, mix of positive and negative – results agreed quite well with (Lerner & Craig, 2002). The duration, frequency, and vividness of the tactile MAE increased linearly with adapting speed.
Planetta & Servos (2010): ditto reliability. Based on different areas of skin tested (cheek, forearm, hand) and their known distribution of mechanoreceptors, suggested that the rate of occurrence of the tMAE may depend on FA1 units, but that the vividness and duration of the effect does not.