ABSTRACT
Among procedures used in the study of animal memory, perhaps the most widely used is the delayed matching to sample or delayed conditional discrimination task (see e.g., Cumming & Berryman, 1965; D'Amato, 1973; Roberts, 1972; Zentall & Hogan, 1977). In a delayed conditional discrimination, reinforcement is provided for a response to stimulus X (but not to stimulus Y) if both were preceded by stimulus A, and reinforcement is provided for a response to stimulus Y (but not to stimulus X) if both were preceded by stimulus B. Thus the comparison or test stimulus (X or Y) to which a response will be reinforced is conditional on the prior presence of a particular initial or sample stimulus (A or B).
