Categorical scaling of stimulus duration by humans.

Normal human adults performed on an analogue of the categorical timing procedure, used by J.G. Fetterman and P.P. Killeen (1995) with pigeons, by classifying a set of 18 or 24 tone durations in 3 or 4 categories. Use of the different categories was an orderly function of stimulus duration in all cases, and data showed a close approximation to superposition, indicating conformity to scalar timing. Both these results were similar to data from pigeons. A model using memory representations of the category-range geometric means with scalar variance fitted data well in nearly all respects. The results emphasize human and animal similarities in categorical timing and conformity of human behavior to scalar timing principles.