The effects of scopolamine on the temporal control of behavior.

Pigeons were provided access to food once every 75 sec independently of their behavior. The effects of scopolamine hydrobromide on the temporal distribution of locomotor activity during the interfood interval were evaluated on the basis of a recently developed model. Drug-induced changes in activity, as evaluated by the model, showed that scopolamine (a) decreased the effect of postfood inhibition, (b) decreased the effect of terminal behaviors that occur late in the interfood interval and compete or interfere with general activity, (c) decreased the total amount of activity engendered by the appetitive schedule of reinforcement, (d) and appeared to produce an underestimation of time intervals. These effects were systematically related to drug dosage.