Amplitude and spatial-period discrimination in sinusoidal gratings by dynamic touch

Harold T. Nefs*, Astrid M L Kappers, Jan J. Koenderink

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


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 μn 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.

Original languageEnglish
Pages (from-to)1263-1274
Number of pages12
Issue number10
Publication statusPublished - 2001
Externally publishedYes


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