title: Amplitude and spatial-period discrimination in sinusoidal gratings by dynamic touch.
abstract: We measured discrimination thresholds for sinusoidal gratings using active dynamic touch. In the first experiment we measured the thresholds for amplitude discrimination as a function of amplitude and spatial period. Thresholds ranged between 10.8%, and 15.8% of the standard amplitude. We showed that amplitude differences as small as 2 microm can be detected. We found that Weber fractions for amplitude discrimination are constant over a range of amplitudes, but are influenced by the spatial period of the grating; discrimination improved with increasing spatial period. In the second experiment we determined the thresholds for spatial-period discrimination. We used the same design as in the first experiment. Weber fractions ranged from 6.4% to 11.8%. Amplitude was found to have no effect on the Weber fractions for spatial-period discrimination. However, the spatial period had an effect on the Weber fractions: larger spatial periods yielded lower Weber fractions.
authors.affiliation: Department of Physics of Man, Helmholtz Institut, Universiteit Utrecht, The Netherlands. h.t.nefs@phys.uu.nl
authors.forename: H T
authors.initials: HT
authors.lastname: Nefs
authors.forename: A M
authors.initials: AM
authors.lastname: Kappers
authors.forename: J J
authors.initials: JJ
authors.lastname: Koenderink
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D015350:Contrast Sensitivity / Q000502:physiology; D004056:Differential Threshold / Q000502:physiology; D004192:Discrimination, Psychological / Q000502:physiology*; D005260:Female; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D008297:Male; D016011:Normal Distribution; D014110:Touch / Q000502:physiology*