Temporal Phrasing and Overshadowing in Rat Serial-Pattern Learning

Abstract

Work on experimental manipulations that affect chunking in sequential learning has shown that cues inserted into a sequence, termed “phrasing cues,” can facilitate learning. Two experiments examined how temporal intervals positioned at chunk boundaries facilitate serial-pattern learning. Experiment 1 showed that rat serial-pattern learning can be facilitated when distinct temporal intervals precede chunk boundaries regardless of whether the intervals are longer or shorter than intervals within chunks. Experiment 2 replicated the acquisition results of Experiment 1 with a different serial pattern. In addition, after both 14 and 35 days of acquisition with phrasing cues, cue removal produced severe deficits in tracking Element 1 of chunks, the element directly after the phrasing cues during acquisition. All in all, the results indicate that rats used both short and long temporal phrasing intervals as discriminative cues and that facilitated learning due to phrasing is not the result of additional processing time provided by longer intertrial intervals at chunk boundaries. Furthermore, many of the finer details of the results could be accounted for by the additional assumption that phrasing cues overshadow interitem associations.