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Serial position effect is the tendency of a person to recall the first and last items in a series best, and the middle items worst. The term was coined by Hermann Ebbinghaus through studies he performed on himself, and refers to the finding that recall accuracy varies as a function of an item's position within a study list. When asked to recall a list of items in any order (free recall), people tend to begin recall with the end of the list, recalling those items best (the recency effect). Among earlier list items, the first few items are recalled more frequently than the middle items (the primacy effect).〔Deese and Kaufman (1957) ''Serial effects in recall of unorganized and sequentially organized verbal material'', J Exp Psychol. 1957 Sep;54(3):180-7〕〔 One suggested reason for the primacy effect is that the initial items presented are most effectively stored in long-term memory because of the greater amount of processing devoted to them. (The first list item can be rehearsed by itself; the second must be rehearsed along with the first, the third along with the first and second, and so on.) The primacy effect is reduced when items are presented quickly and is enhanced when presented slowly (factors that reduce and enhance processing of each item and thus permanent storage). Longer presentation lists have been found to reduce the primacy effect. One theorized reason for the recency effect is that these items are still present in working memory when recall is solicited. Items that benefit from neither (the middle items) are recalled most poorly. An additional explanation for the recency effect is related to temporal context: if tested immediately after rehearsal, the current temporal context can serve as a retrieval cue, which would predict more recent items to have a higher likelihood of recall than items that were studied in a different temporal context (earlier in the list). The recency effect is reduced when an interfering task is given. Intervening tasks involve working memory, as the distractor activity, if exceeding 15 to 30 seconds in duration, can cancel out the recency effect. Additionally, if recall comes immediately after test, the recency effect is consistent regardless of the length of the studied list,〔 or presentation rate. Amnesiacs with poor ability to form permanent long-term memories do not show a primacy effect, but do show a recency effect if recall comes immediately after study. People with Alzheimer's Disease exhibit a reduced primacy effect but do not produce a recency effect in recall. ==Primacy effect== The primacy effect, in psychology and sociology, is a cognitive bias that results in a subject recalling primary information presented better than information presented later on. For example, a subject who reads a sufficiently long list of words is more likely to remember words toward the beginning than words in the middle. Many researchers tried to explain this phenomenon through free recall tests. In some experiments in the late 20th century, it was noted that participants who knew that they were going to be tested on a list presented to them would rehearse items. Meaning, as items were presented, the participants would repeat those items to themselves and as new items were presented, the participants would continue to rehearse previous items along with the newer items. It was demonstrated that the primacy effect had a greater influence on recall when there was more time between presentation of items so that participants would have a greater chance to rehearse previous (prime) items. Overt-Rehearsal was a technique that was meant to test participants' rehearsal patterns. In an experiment using this technique, participants were asked to recite out loud the items that come to mind. In this way, the experimenter was able to see that participants would repeat earlier items more than items in the middle of the list, thus rehearsing them more frequently and having a better recall of the prime items than the middle items later on. In another experiment, by Brodie and Murdock, the recency effect was found to be partially responsible for the primacy effect. In their experiment, they also used the overt-rehearsal technique and found that in addition to rehearsing earlier items more than later items, participants were rehearsing earlier items later on in the list. In this way, earlier items were closer to the test period by way of rehearsal and could be partially explained by the recency effect. In 2013, a study showed that primacy effect is also prominent in decision making based on experience in a repeated choice paradigm, a learning process also known as operant conditioning. The authors showed that there is a large importance to the value of the first reward on subsequent behaviour, a phenomenon they denoted as outcome primacy. In another study, the subjects received one of two sentences. For example, one may be given "Steve is smart, diligent, critical, impulsive, and jealous." and the other "Steve is jealous, impulsive, critical, diligent, and smart." These two sentences contain the same information. The first one suggests positive trait at the beginning while the second one has negative traits. Researchers found that the subjects evaluated Steve more positive when given the first sentence, compared to the second one.〔Asch, S. (1946). Forming impressions of personality. ''Journal of Abnormal and Social Psychology,41,'' 258–290. 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Serial position effect」の詳細全文を読む スポンサード リンク
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