Nicotine does not enhance discrimination performance in a temporal bisection procedure.

Recent reports of selective disruption of stimulus control by drug administration and other disruptive operations in temporal discrimination procedures may be interpreted as a disruption of attention to the temporal sample stimuli. This experiment assessed the effects of nicotine, a compound that has been widely shown to increase measures of attention, on temporal discrimination performance. Pigeons responded under a psychophysical choice procedure in which responses to one key color were correct after presentation of four shorter sample durations and responses to another key color were correct after presentation of four longer sample durations. Performance under nicotine was characterized by using a model that differentiates the effects of nicotine on stimulus control, bias, and sensitivity of temporal discrimination. Nicotine selectively decreased the measure of stimulus control, but did not systematically affect the measures of timing. Mecamylamine (1.0 mg/kg) failed to antagonize the disruptive effects of nicotine. These results suggest that disruption of temporal discrimination performance in this preparation may not have been dependent on the specific pharmacology of nicotine and underscore the importance of quantitative separation of the effects of various manipulations on stimulus control from effects on timing.