LEARNING NEW RESPONSE SEQUENCES

Four rats were required to press either a right or left lever to compl ete various three-response sequences. After extended exposure to a tra ining sequence, subjects were shifted to a new target sequence. The ne w target sequences always differed from the previous sequence by the r esponse required in the first or last position of the sequence. Subjec ts were repeatedly exposed to all possible combinations of training an d new target sequences. Learning of new sequences occurred more rapidl y when the change in the new target sequence was in the last position. Errors persisted longer in new sequences in which the change was in t he first position. Extinction of the training sequence occurred faster when the change was in the last position. Responses in the last posit ion were considerably more sensitive to the shift to new target sequen ces than were responses in the first position. Even though response se quences may form new behavioral units from the training sequence, rein forcement and extinction acted differentially on the individual lever presses within new target sequences rather than on the sequences as a whole. These findings support the hypothesis that response strength is determined by contiguity to reinforcement.