Is memory for plans unique? a study using common nouns as stimuli

The present study explored the question of whether the U-shape effect, which was observed in previous experiments on memory for fictitious plans is unique to the memory for plans or not, i.e., are plans for the morning and for the evening recalled better than those for the afternoon. To investigate we used a "common noun" as the material to be memorized instead of the "action phrase" as used in Watanabe and Kawaguchi's earlier experiments. Free recall tasks were performed in two experiments: in Exp. 1, a sample of 15 undergraduates memorized "hour" and "common noun" pairs, while in Exp. 2 another 15 undergraduates memorized "number" and "common noun" pairs. The results of these experiments indicated no significant effect for time of day. This suggests that the U-shape effect observed in Watanabe and Kawaguchi's experiments, in which participants were asked to memorize a combination of an "hour" and an "action phrase" is unique to memory for plans.