EFFECT OF INTERRUN INTERVAL ON SERIAL PATTERN LEARNING IN RATS

The effect of interrun interval (IRI) on serial pattern learning was investigated in a runway. One of two serial sequences, a monotonic decreasing sequence (14-7-3-1-0 food pellets) or a nonmonotonic sequence (14-1-3-7-0), was combined factorially with a short (30 s) or a long (30 min) IRI. Following 28 acquisition trials, a short (or long) IRI was transferred to the same sequence with a long (or short) IRI. It was found that anticipation of the 0-pellet developed more rapidly in the group receiving a monotonic sequence with a 30 s IRI than that with a 30.min IRI in acquisition phase. The 0-pellet was not anticipated by either of the two nonmonotonic groups. Anticipation was eliminated by the increase in IRI, whereas it was developed by the decrease in IRI in the monotonic sequence. These results suggest that time-related factors such as the decay of the memory of numbers of pellets are needed for Capaldi's memory discrimination theory.