Disruption of temporal discrimination and the choose-short effect.

The present experiment examined the effects of several disruptors on temporal discrimination. Pigeons responded under a 0-delay symbolic matching-to-sample procedure in which responses to one key color were reinforced following the presentation of four shorter sample durations, and responses to another key color were reinforced following the presentation of four longer sample durations. Steady-state performance was disrupted by presession feeding, intertrial-interval food, visual distraction, and extinction. All disruptors decreased temporal-discrimination accuracy. Analyses of the fitted cumulative normal functions indicated that decreases in accuracy were produced mainly by decreases in overall stimulus control rather than specific effects on timing. In addition, all disruptors selectively decreased accuracy on long-sample trials--a choose-short effect. This effect is interpreted in terms of decreased attention to the samples under disruption. Current theories of the choose-short effect do not appear to easily account for these results.