Interseries Transfer and Effect of Retention Interval in Rats' Serial Pattern Learning

Abstract

The experiment with 24 rats assessed the persistence of memory on formally defined rule structure of food quantity sequence using serial pattern learning followed by transfer test. In original training, monotonic (M) group was presented with the monotonic decreasing series consisting of two, three, or four different items of 45mg food pellets, whereas Random (R) group was provided with the random series in which items were arranged with no consistent relations among them. After the original training was finished, each of these basic groups was divided into two groups. Transfer training was begun on the day after the end of original training for groups MI and RI, whereas on the 21st day after the end of original training for groups MD and RD. In transfer training, all groups received a novel monotonic decreasing series containing 16-9-3-1-0 pellets. Throughout transfer training, groups MI and MD anticipated the 0 pellet item in this series significantly better than groups RI and RD, and any reliable difference was not observed between groups MI and MD, or groups RI and RD. These results indicate that rats' memory for the sequentially arranged food quantities with simple rule structure has strong persistence against to time lapse. Implications of these findings are discussed in relation to the partial reinforcement delayed extinction effect which shows persistent extinction performance after regularly alternating schedules.