Manual discrimination of force using active finger motion.
In these experiments, two plates were grasped between the thumb and forefinger and squeezed together along a linear track. An electromechanical system presented a constant resistance force during the squeeze up to a predetermined location on the track, whereupon the force effectively went to infinity (simulating a wall) or to zero (simulating a cliff). The task of the subject was to discriminate between two alternative levels of the constant resistance force (a reference level and a reference-plus-increment level). Results of these experiments indicate a just noticeable difference of roughly 7% of the reference force using a one-interval paradigm with trial-by-trial feedback over the ranges 2.5 less than or equal to F0 less than or equal to 10.0 newtons, 5 less than or equal to D less than or equal to 30 mm, 45 less than or equal to S less than or equal to 125 mm, and 25 less than or equal to V less than or equal to 160 mm/sec, where F0 is the reference force, D is the distance squeezed, S is the initial fingerspan, and V is the mean velocity of the squeeze. These results, based on tests with 5 subjects, are consistent with a wide range of previous results, some of which are associated with other body surfaces and muscle systems and many of which were obtained with different psychophysical methods.
Pang
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XD
Massachusetts Institute of Technology, Cambridge 02139.
Tan
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Durlach
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D001696:Biomechanical Phenomena; D004056:Differential Threshold; D005385:Fingers / Q000502:physiology*; D006801:Humans; D007699:Kinesthesis / Q000502:physiology*; D009068:Movement; D005082:Physical Exertion / Q000502:physiology*; D011434:Proprioception / Q000502:physiology*; D011601:Psychophysics