抄録
Three experiments examined how intervals of added sequences affected rat's learning of the reinforcement pattern. Animals were trained for runway performance corresponding to the series of one reinforcement trial (R) and two nonreinforcement trials (N) run with 30-s ITIs. The series was NNR, RNN, NRN for Experiments 1, 2, 3, respectively, Following this acquisition training, a second series of three nonreinforced trials with 30-s ITIs was added to the first series. Animals were assigned to two groups matched for performance level and they were given an added series with either long or short inter-session intervals. Subjects in Group S-ITI were given totally six trials with 30-s ITIs, while subjects in Group L-INT were given 30-min between the first and second series. Running speed for the first series differed with structure of the series (reinforcement pattern). The pattern of running speed for added series (Trials 4-6) was similar to that for original series (Trials 1-3) in Group L-INT, while running speed was kept at a low level for added series of nonreinforced trials in Group S-ITI. As is suggested by these findings, the events regularly occurred with equal ITIs can be remembered as one series, even when a new series of events is added to already experienced one with the same ITIs. However, when the second series is temporally separated from the first one by long intervals, the memory system may be reset so that events can be segregated as two sequences.
