EFFECTS OF DISCRIMINABILITY, PROBABILITY OF REINFORCEMENT, AND HANDLING COST ON VISUAL-SEARCH AND PREY CHOICE

Pigeons searched for two targets that varied in similarity to items in the background. The targets, simulating ''prey,'' were small alphabet ic characters presented on computer monitors among distracter characte rs. In the first experiment, the probability of reinforcement for peck ing at the targets was manipulated. In the second experiment, the resp onse requirement for one of the targets was varied. Changing the proba bility of reinforcement Zed to more efficient search and increased cho ice for the more reinforced item. This effect carried over to subseque nt equal reinforcement baseline conditions. Increasing the response re quirement for one item increased response time for that item and reduc ed choice of the item. This effect did not carry over to a subsequent baseline condition. The results suggested that a high probability of r einforcement resulted in improved detection of the item, perhaps throu gh perceptual learning, and increased the incentive that motivated res ponse to the item, but that high response requirement resulted only in an incentive shift.