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Tactile discrimination of thickness.
K T John1, A W Goodwin, I Darian-Smith
1Department of Anatomy, University of Melbourne, Parkville, Victoria, Australia.
Experimental Brain Research
|January 1, 1989
Summary
Human subjects can discriminate subtle differences in metal plate thickness using touch. Surprisingly, including plate edges in the grip did not improve thickness discrimination ability.
Area of Science:
- Neuroscience
- Human Perception
- Biophysics
Background:
- The sense of touch is crucial for object interaction and material property assessment.
- Understanding the limits of tactile discrimination informs our knowledge of somatosensation.
Purpose of the Study:
- To quantify human ability to discriminate subtle variations in the thickness of plane metal plates.
- To investigate the role of plate edges in tactile thickness discrimination.
Main Methods:
- A forced-choice paradigm was employed to measure discrimination thresholds.
- Subjects gripped metal plates (copper-plated brass) between the thumb and index finger.
- Discrimination was tested with and without the inclusion of plate edges in the grip.
Main Results:
- A thickness difference of approximately 0.075 mm was discriminable when plate edges were not touched.
- Tactile discrimination performance did not improve when plate edges were included in the grip.
- Hypothesized strategies suggest a required precision of ~0.1 degrees in sensing finger joint angles.
Conclusions:
- Human tactile perception can detect minute changes in material thickness.
- Edge information does not appear to enhance tactile thickness discrimination in this paradigm.
- Fine motor control and joint angle sensing are critical for precise tactile judgments.