The University of Auckland.
J Exp Anal Behav. 2011 Sep;96(2):227-41. doi: 10.1901/jeab.2011.96-227.
Reinforcers may increase operant responding via a response-strengthening mechanism whereby the probability of the preceding response increases, or via some discriminative process whereby the response more likely to provide subsequent reinforcement becomes, itself, more likely. We tested these two accounts. Six pigeons responded for food reinforcers in a two-alternative switching-key concurrent schedule. Within a session, equal numbers of reinforcers were arranged for responses to each alternative. Those reinforcers strictly alternated between the two alternatives in half the conditions, and were randomly allocated to the alternatives in half the conditions. We also varied, across conditions, the alternative that became available immediately after a reinforcer. Preference after a single reinforcer always favored the immediately available alternative, regardless of the local probability of a reinforcer on that alternative (0 or 1 in the strictly alternating conditions, .5 in the random conditions). Choice then reflected the local reinforcer probabilities, suggesting some discriminative properties of reinforcement. At a more extended level, successive same-alternative reinforcers from an alternative systematically shifted preference towards that alternative, regardless of which alternative was available immediately after a reinforcer. There was no similar shift when successive reinforcers came from alternating sources. These more temporally extended results may suggest a strengthening function of reinforcement, or an enhanced ability to respond appropriately to "win-stay" contingencies over "win-shift" contingencies.
强化物可以通过反应强化机制来增加操作性反应的发生概率,或者通过某种辨别过程,使更有可能提供后续强化的反应本身更有可能发生。我们检验了这两种解释。六只鸽子在两种选择的转换键同时呈现的程序中,通过啄键来获取食物强化物。在一次实验中,两种选择上安排的强化物数量相等。在一半的条件下,两种强化物在两种选择之间严格交替出现,而在另一半条件下,两种强化物随机分配给两种选择。我们还在不同的条件下,改变了在强化物之后立即可用的选择。无论在该选择上的强化物的局部概率(在严格交替条件下为 0 或 1,在随机条件下为 0.5)如何,单次强化物后的偏好总是偏向于立即可用的选择。选择反映了局部强化物的概率,这表明强化具有某种辨别属性。在更广泛的层面上,来自一个选择的连续相同选择的强化物系统地改变了对该选择的偏好,无论强化物之后立即可用的是哪个选择。当连续的强化物来自交替的来源时,就不会出现这种类似的变化。这些更具时间扩展性的结果可能表明强化具有强化作用,或者能够更恰当地应对“赢留”而不是“赢移”的连续变化。