Three-trial sequences of reward magnitudes with odor cues maximized

Abstract

Albino rats were trained in a straight runway for three trials on each of 24 days. Five pellets were received on the third trial of each day, whereas the amounts of Trials 1 and 2 were either 20 or 0 pellets. Whether the daily sequence was 20-0-5 or 0-20-5 was determined by pseudorandom orders. To maximize odor cues, animals were run in rotation, with every rat receiving the same reward sequence within a day. The data during asymptotic performance shows stronger evidence of the control of running by nonreward odor when nonreward was the Trial 1 outcome than when nonreward was the Trial 2 outcome. There was no evidence for differential control of performance by odor cues when the trial outcome was 20 pellets as opposed to 5 pellets. The findings are discussed in relation to other sources of mediation of patterned running that were controlled in the present design.