Serial Anticipation and Transfer in Reversed Series with Rats

Rats were trained in a runway with one of two serial patterns of reward. In one series, the five successive runs of the series ended in 14, 9, 1, 1, and 0.045-g pellets of reward respectively (14-9-1-1-0). The other series was 14-5-5-1-0. Intervals between runs within a series were about 20 s, and intervals between the series, which were administered twice each day, were about 20 min. After 12 training days, the series were reversed (0-1-1-9-14 and 0-1-5-5-14), and reversal training continued for 6 days. Rats trained with the 14-9-1-1-0 series quickly developed correct anticipation of the terminal 0-pellet element of the series, but training with the 14-5-5-1-0 series never produced clear anticipation. The initial effect of the reversal was a disruption, evidenced by slow running on the middle run of both series, but that disruption gave way eventually to correct anticipation of the initial 0-pellet element in both series.