*p<.05
DISCUSSION
Previous studies (Toyota, 1989) showed that targets with pleasant or vivid episodes were recalled more often than those with unpleasant or dull epi­sodes. The present study also indicated that the rating scores for pleasantness and vividness with recalled targets were higher than those with non-recalled targets. The nostalgia rating score for recalled targets was higher than that for non-recalled targets. These results show that nostalgia, pleasantness, and vividness determine the effectiveness of autobiographical elaboration.
The primary purpose of the present study was to examine the prediction that positive correlations among rating scores of attributes and higher alpha were observed in recalled targets. Nonetheless, those correlations and alpha were not in non-recalled targets. The results showed a positive correlation be­tween vividness and nostalgia attributes, and a higher alpha was observed in recalled targets. Notwithstanding, no correlations and low alpha were observed in non-recalled targets. These results supported the prediction and indicat­ed that strong relations among attributes in an episode led to effective autobiographical elab­oration. According to Hunt (2006), distinctiveness is a critical memory factor. Thus, the results were interpreted regarding their distinctiveness. Epi­sodes with strongly connected attributes make the targets more distinctive than those with weak attributes. Therefore, the effectiveness of autobiographical elaboration is determined by the strong relations among the attributes of an episode with a target.
Although the present study indicated the importance of relations among attributes in an episode, the most crucial attribute for effective autobiographical elaboration has not been clarified. Toyota (1995) showed that targets with episodes with the high­est vividness ratings were recalled more often than those with the high­est pleasant ratings. This result was interpreted as indicating the superiority of vividness to pleasantness. The present study results indicated that the effect size of vividness was larger than that of the oth­er two attributes, pleasantness and nostalgia. Therefore, it can be inferred that vividness is the most effective attribute. However, the effects of combinations of attributes, such as vivid, pleasant, and nostalgic, on recall were not examined. Further research is required to explore the most effective combination of attributes in an episode.
Finally, the methodological problems should be addressed. This is about the procedure of the rating episode phase. Participants were required to rate the degree of each attribute in an episode associated with a target word in the orienting task phase. However, as a time lag existed between the orienting task phase and the rating episode phase, possibly, each participant could not precisely remember the episode elicited by each target during the orienting task phase. This problem was indicated in a previous study (Toyota, 2012) us­ing the power-point slide presentation procedure. It is difficult for participants to rate in such a presentation because the targets were presented on a screen at the front of the class­room and the rating sheet was close to them.
Further research is necessary to provide a booklet of targets for each participant and rate the degree of attributes in an episode with each target during the orient­ing task phase. Another problem concerns the attributes of the target word it­self. As the present study focused on the episode elicited by each target, the attributes of each target word itself have not been examined precisely. For example, if each target is associated with general episodes, such as a book eliciting an episode of studying hard, it would be difficult to discriminate between general episodes and personal episodes with each target.
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