Learning and generalization of time production in humans: rules of transfer across modalities and interval durations

This article investigated both the ability of naive human subjects to learn interval production, as well as the properties of learning generalization across modalities and interval durations that varied systematically from the over-trained interval. Human subjects trained on a 450-, 650-, or 850-ms single-interval production task, using auditory stimuli to define the intervals, showed a significant decrease in performance variability with intensive training. This learning generalized to the visual modality and to non-trained durations following a Gaussian transfer pattern. However, the learning carryover followed different rules, depending on the duration of the trained interval as follows: (1) the dispersion of the generalization curve increased as a function of the trained interval, (2) the generalization pattern was tilted to the right in the visual condition, and (3) the transfer magnitude for 650 ms was less prominent than for the other two intervals. These findings suggest the existence of neural circuits that are tuned to specific time lengths and that show different temporal processing properties depending on their preferred interval duration.