Serial learning in rats: A test of three hypotheses

Findings obtained by providing rats with a single fixed series of events, A-B-C-…, often are equally compatible with three alternative serial learning interpretations: that the signal for items is (A) their position in the series (position view), (B) the prior item of the series (chaining view), and (C) one, two, or more prior items of the series (sequential view). By employing a novel procedure of supplying rats with two different series, rather than a single series, it was possible to choose between the three alternatives. Employing 10 and 0, 0.045 g, Noyes pellets as items, rats in both runway experiments reported here received a three trial series, either a 10-0-10 series or a 0-0-10 series. In Experiment 1, the other series was a single 0 pellet trial (along with 10-0-10) or a single 10 pellet trial (along with 0-0-10). In Experiment 2, the other series was either 0-0 (along with 10-0-10) or 10-0 (along with 0-0-10). Considering both experiments, findings were consistent with the sequential view but not with either the position view or the chaining view. The possibility was suggested that, under some other experimental conditions, particularly those not employing reward events as items, greater control over discriminative responding might be exercised by position cues than by item cues.