Resurgence: the role of extinction.

Three hens were trained to door push and three were trained to head bob using food as the reinforcer (Behaviour 1 training). A period of extinction followed. Each hen was then trained to perform the other behaviour (Behaviour 2) and this was followed by seven sessions of extinction. This whole sequence was repeated six times, with two sessions of extinction following Behaviour 1 training. Over the repeated extinction conditions there were decreases in responding early in extinction, for both Behaviours 1 and 2, compared with the first condition. Behaviour in the later extinction sessions could be studied for Behaviour 2 only, and it was found to increase relative to the first condition, over repeated extinction conditions. The occurrence of Behaviour 1 during the extinction following the training of Behaviour 2, that is the resurgence of Behaviour 1, both over the whole of and in the first session of each extinction phase, was variable and tended to increase over these six conditions. Thus it is possible to study resurgence using a within-subject design but the effect of repeated extinction conditions needs to be considered. The period of extinction immediately following Behaviour 1 training was then increased to nine sessions for two replications of the whole sequence. This was followed by two repeats of the sequence with no sessions of this extinction and then by another repeat, with nine sessions of this extinction phase. Over these five conditions the total resurgence of Behaviour 1 was generally greater when there were no sessions of extinction immediately following Behaviour 1 training, than when there were nine sessions. This result was more marked for the resurgence of Behaviour 1 in the first session of the extinction of Behaviour 2. Thus, these data support the hypothesis that the resurgence of Behaviour 1 is the result of the prevention of the extinction of Behaviour 1 by training Behaviour 2. At a similar point in extinction, the number of occurrences of Behaviour 1 in its own extinction was not significantly different from the number of occurrences of Behaviour 1 during the extinction of Behaviour 2. This fails to support the hypothesis that resurgence is induced by the extinction of Behaviour 2.