ラットの報酬系列パタン学習における走行間手がかりの操作による分節化効果

抄録

The present study examines the phrasing effect, without temporal or spatial grouping, in serial pattern learning in rats. Rats were trained with a 14-7-3-1-0-14-7-3-1-0 series per day, consisting of a varying number of 45 mg food pellets, in a straight runway with a 20 s inter-run interval (IRI). Rats were kept in a bright or dark holding cage during the IRI. The Unphrased Group was kept in one of the two cages throughout each presentation series, whereas for the Phrased Group, the holding cage was changed to the alternate cage only during the IRI between the fifth and sixth runs. Thus, this unique cage cue could be a phrasing indication that would divide the subpatterns without any temporal or spatial grouping. The Phrased Group showed better serial learning performance than the Unphrased Group. In the extinction test, the phrasing cue increased running speeds only in the Phrased Group, not in the Unphrased Group. These results show that presentation of a phrasing cue without temporal or spatial grouping can produce a phrasing effect, supporting the prediction of the memory-discrimination learning theory that assumes overshadowing of inter-item association by phrasing cues.