Positive Transfer across Grouping Cue Modalities in Rat Serial Learning

Abstract

In Experiment 1, three groups of rats ( n = 4) received four successive repetitions daily of the three-trial series of reinforced (R) and nonreinforced (N) trials RNR. In Group B, a change in runway brightness (/) served as a grouping cue to signal the start of each series repetition, e.g., RNR/RNR/RNR/RNR. In Group T, a relatively long intertrial interval served as a grouping cue, e.g., RNR–––RNR–––RNR–––RNR. Group C was trained in Phase 1 with no grouping cue, e.g., RNRRNRRNRRNR. Groups B and T were superior to Group C in learning to anticipate the events of the RNR series, a result consistent with the hypothesis that those groups would organize the 12-item list into groups of three trials presented recursively. Following Phase 1, groups were shifted from temporal grouping to brightness grouping and vice-versa and to a tactile grouping cue condition. Except for shifts from temporal to brightness grouping, correct responding survived cross-modal shifts in grouping cues. Experiment 2 employed a subtly modified series of reinforcement events and showed that positive transfer could also be obtained in subjects shifted from temporal to brightness grouping. The results support the view that grouping cues employed in rat serial learning investigations are not discriminative cues for particular groupings of reinforcement events.