Differential and non-differential probability of reinforcement in a conditional discrimination task [Probabilidad de reforzamiento diferencial y no diferencial en una tarea de discriminación condicional]

Using a conditional discrimination task, the correct responses for a group of rats (DO) were reinforced with different probabilities (0.8 versus 0.4) depending the conditional cue; whereas for another group (NDO) the correct responses were reinforced with the same probability of reinforcement (0.6). After the training (acquisition), the retention interval and the delay of reinforcement were introduced in different phases. The subjects trained with differential outcomes (DO) had a faster acquisition and reached higher discrimination index than non-differential group (NDO). The retention interval results in lower discrimination index in NDO group than in DO group; no differential changes in accuracy were observed by the delay of reinforcement. The results extend the differential outcomes effect to a two-choice conditional discrimination task with rats varying the probability of reinforcement. The absence of delay of reinforcement effect is discussed