Multiple-pattern learning by rats on an eight-arm radial maze

Rats were trained over a number of sessions on an eight-arm radial maze with eight trials on each session. Each of four arms on the maze contained a different pattern formed by sequences of reward (two pellets) or nonreward (no pellets) over successive trials within sessions. The patterns were single alternation, double alternation, and two patterns in which four rewards or four nonrewards were preceded and followed by two nonrewards or two rewards, respectively. The other four arms on the maze served as control arms and always contained one pellet. It was found that rats tracked all of these patterns when they were required to climb over barriers to enter and leave arms. However, rats showed no ability to extrapolate patterns beyond the training trials. These findings, and a further analysis of arm-choice stereotypy, led to the conclusion that rats tracked by using a trial-number strategy.