Wakeful rest alleviates interference-based forgetting

Retroactive interference (RI)—the disruptive influence of events occurring after the formation of a new memory—is one of the primary causes of forgetting. Placing individuals within an environment that postpones interference should, therefore, greatly reduce the likelihood of information being lost from memory. For example, a short period of wakeful rest should diminish interference-based forgetting. To test this hypothesis, participants took part in a foreign language learning activity and were shown English translations of 20 Icelandic words for immediate recall. Half of the participants were then given an 8-min rest before completing a similar or dissimilar interfering distractor task. The other half did not receive a rest until after the distractor task, at which point interference had already taken place. All participants were then asked to translate the Icelandic words for a second time. Results revealed that retention was significantly worse at the second recall test, but being allowed a brief rest before completing the distractor task helped reduce the amount of forgetting. Taking a short, passive break can shield new memories from RI and alleviate forgetting.     

The crucial role of postcue encoding in directed forgetting and context-dependent forgetting

People can intentionally forget previously studied material if, after study, a forget cue is provided and new material is learned. It has recently been suggested that such list-method directed forgetting arises because the forget cue induces a change in internal context and causes context-dependent forgetting of the studied material (L. Sahakyan & C. M. Kelley, 2002). The authors compared directed forgetting and context-dependent forgetting by examining whether, like a forget cue, a change in internal context needs subsequent learning of new material to be effective. Participants studied an item list and, after study, received a remember cue or a forget cue or their internal context was changed through an imagination task. In each condition, half the participants learned a second list, and the other half fulfilled an unrelated distractor task. Both the forget cue and the change in internal context induced forgetting of the first list only when learning of the second list was interpolated. These results suggest that postcue encoding of new material is crucial for both directed forgetting and (some forms of) context-dependent forgetting.     

List-method directed forgetting: The forget cue improves both encoding and retrieval of postcue information

In list-method directed forgetting, people are cued to forget a previously studied item list and to learn a new list instead. Such cuing typically leads to forgetting of the first list and to memory enhancement of the second, referred to as list 1 forgetting and list 2 enhancement. In the present study, two experiments are reported that examined influences of items' serial learning position in a list and the two lists' output order on list-method directed forgetting. The results show that list output order influences list 2 enhancement but not list 1 forgetting. The enhancement was higher when list 2 was recalled first than when list 1 was recalled first and, in both cases, was higher for early list 2 items than for middle and late list 2 items. In contrast, the forgetting was equally present for all list 1 items and did not depend on the two lists' output order. The findings suggest that two separate factors can contribute to list 2 enhancement: one (encoding) factor that is restricted to early list 2 items and does not depend on list output order, and another (retrieval) factor that pertains to all list 2 items and varies with the two lists' output order. A new two-mechanism account of directed forgetting is suggested that reconciles previous (encoding or retrieval) views on list 2 enhancement.     

Short-term temporal changes in free recall

An experimental study of short-term memory for lists of familiar English words is reported. Lists of 10, 20, and 30 unrelated words were presented at a 1-sec. rate. Retention was measured by free recall after intervals of 0, 15 and 30 sec. A counting task was used to prevent rehearsal during the retention interval. The absolute level of recall increased with length of list whereas the percentages retained showed the reverse trend. The recall scores decreased steadily as a function of retention interval, with the rates of forgetting comparable for the three lengths of list. The decline in the amount recalled was due in large measure to the loss of the terminal items in the list. Consequently, the pronounced recency effect present on the immediate test of recall was progressively reduced as a function of time. By contrast retention of the initial part of the list was relatively stable. These variations in rate of forgetting are attributed to differences among serial positions in susceptibility to proactive inhibition.     

Selective cues to forget can fail to cause forgetting

Recent research has found that individuals can selectively forget a subset of items through directed forgetting. The goal of the present study was to replicate this selective directed forgetting effect and elucidate its underlying mechanisms. Unfortunately, results from four experiments failed to find any evidence of selective directed forgetting. Participants failed to forget any items when instructed to forget a subset of items from a first list before learning a second list. Participants were only successful in forgetting items from the first list when they were instructed to forget all items from the first list before learning the second list.     

Directed forgetting in young children: Evidence for a production deficiency

When people are cued to forget a previously studied list of items and to learn a new list instead, such cuing typically leads to forgetting of the first list and to memory enhancement of the second. In two experiments, we examined such listwise directed forgetting in children (and adults), using a forget cue that placed either high emphasis or low emphasis on the need to forget. In the low-emphasis condition, (adult-like) List 1 forgetting was present in fourth graders, but not in first graders (and kindergartners); in contrast, in the high-emphasis condition, (adult-like) List 1 forgetting was present from first grade on. Only fourth graders showed (adult-like) List 2 enhancement, regardless of task instruction. The finding that first graders showed List 1 forgetting only in the high-emphasis condition points to a production deficiency in first graders’ directed forgetting, suggesting that the children are capable of intentional forgetting but fail to do so spontaneously. The finding that first graders showed List 1 forgetting without List 2 enhancement suggests that the two directed-forgetting effects are mediated by different processes with different developmental trajectories.     

COMPARAISON INTERLINGUISTIQUE DE MATÉRIEL VERBAL PROPRE A L'APPRENTISSAGE DE CONCEPT1

Inter-language comparison of verbal material for the study of concept formation. — A list of 215 French words, which were translation equivalents of the words in Underwood and Richardson's (1956) published list, were presented to 119 French students from which single, restricted to sense impression associates were obtained. A systematic inter-language comparison is established and differences between French and English speaking subjects discussed. The piocedure adopted by Mednick and Halpern (1962) to study the ease of concept attainment as a function of Associative Rank has been applied to French subjects. A replication using a direct translation of the English nouns shows no difference between concepts at Associative Rank 1 and 2. It appears indeed from norms of the French group that the concepts selected are balanced not only with respect to Dominance Level but also with respect to Mean Associative Rank. But further experiment, with a material established according to the norms of the French list of associates, shows a very significant difference in the mean number of trials taken to solve each concept. It thus strengthened the assumption of homogeneity of associative response hierarchies in a given language community.     

Very long-term memory for knowledge acquired at school and university

Recent research into the very long-term retention of knowledge originally acquired during the process of formal education at school and university has demonstrated that such knowledge may be retained at high levels over very long retention intervals. The pattern of retention typically takes the form of a comparatively short period marked by forgetting (lasting between 1 and 6 years) followed by a long period of stable retention (usually longer than 30 years). For courses taken at school the level attained over a series of courses (e.g. in learning a foreign language or studying mathematics) is an important determinant of long-term retention. Students who attain moderate or advanced levels of learning show high levels of retention with very little forgetting, whereas students who attain only lower levels of learning show steady forgetting, and after a period of 6 years retain very little knowledge. Similar patterns of retention are present for university students taking single courses in science and literature subjects, and students with higher grades retain more knowledge although the reliable relationship here, between grade obtained and amount remembered, is weak and accounts for only small portions of the variance in retention. Taken together these findings suggest that the retention of knowledge acquired through formal education persists over longer periods of time than popularly believed. Recent theory proposes that these long-lasting effects of education are partly related to the types of learning schedules followed during acquisition and partly related to the nature of the to-be-acquired knowledge, and to whether or not knowledge can be represented schematically.     

Semantic access in number word translation: the role of crosslingual lexical similarity

The revised hierarchical model of bilingualism (e.g., Kroll & Stewart, 1994) assumes that second language (L2) words primarily access semantics through their first language (L1) translation equivalents. Consequently, backward translation from L2 to L1 should not imply semantic access but occurs through lexical wordform associations. However, recent research with Dutch-French bilinguals showed that both backward and forward translation of number words yields a semantic number magnitude effect (Duyck & Brysbaert, 2004), providing evidence for strong form-to-meaning mappings of L2 number words. In two number-word translation experiments with Dutch-English-German trilinguals, the present study investigated whether semantic access in L1-L2 and L1-L3 number-word translation depends on lexical similarity of the languages involved. We found that backward translation from these more similar language pairs to L1 still yields a semantic magnitude effect, whereas forward translation does not, in contrast with the Dutch-French results of Duyck and Brysbaert (2004). We argue against a dual route model of word translation and suggest that the degree of semantic activation in translation depends on lexical form overlap between translation equivalents.     

Effect of the difficulty of prior items on the magnitude of judgments of learning for subsequent items

Research on metacognition often uses various kinds of paired-associate items (e.g., foreign language translation equivalents) to investigate judgments of learning (JOLs) under the assumption that the JOLs are made independently of each other. We tested this assumption by exploring the effect of manipulating the difficulty of prior Swahili-English translation equivalents to determine whether there is a contrasting change in the magnitude of the JOLs assigned to subsequent Swahili-English translation equivalents (e.g., intermediate-difficulty items might receive lower JOLs when following easy items than when following difficult items). The magnitude of JOLs for the subsequent items did not vary as a function of the difficulty of the prior items, even when there were 10 prior items of homogeneous difficulty that differed from the difficulty of the subsequent to-be-judged items.     

Self-evaluation as a moderating factor of strategy change in directed forgetting benefits

In list method directed forgetting, instructing people to forget a studied word list usually results in better recall for a newly studied list. Sahakyan and Delaney (2003) have suggested that these benefits are due to a change in encoding strategy that occurs between the study of the first list and the study of the second list. To investigate what might mediate such strategy change decisions, in two experiments we induced bothforget and remember participants to evaluate their memory performance on the two lists. In Experiment 1, they were asked to explicitly recall the items from the first list before studying the second list. In Experiment 2, after the study of the first list, the participants provided a rapid aggregate judgment of learning. Evaluation eliminated the differences between the forget and remember groups for the second list in both experiments, because the remember group achieved recall levels comparable to those for the forget group. The role of performance evaluation in mediating directed forgetting benefits is discussed.     

Degree of learning,interpolated tests,and rate of forgetting

The purpose of the two experiments reported here was to observe the effects of degree of learning, interpolated tests, and retention interval, primarily on the rate of forgetting of a list of words, and secondarily on hypermnesia for those words. In the first experiment, all the subjects had one study trial on a list of 20 common words, followed by two tests of recall. Half of the subjects had further study and test trials until they had learned the words to a criterion of three correct consecutive recalls. Two days later, half of the subjects under each learning condition returned for four retention tests, and 16 days later, all the subjects returned for four tests. Experiment 2 was similar, except that all the subjects had at least three study trials followed by four recall tests on Day 1, intermediate tests were given 2 or 7 days later, and they all had final tests 14 days later. The results showed that rate of forgetting was attenuated by an additional intermediate set of tests but not by criterion learning. Hypermnesia was generally found over the tests that were given after a retention interval of 2 or more days. The best predictor of the amount of hypermnesia over a set of tests was the difference between overall cumulative recall and net recall on the first test of the set.     

False memories for script actions in a mugging account

Abstract

A number of cross-language priming experiments are reported that evaluate whether word meanings in the first and second language are represented in common or separate systems. A masked priming procedure was used on the assumption that when prime awareness is limited, any priming effects directly reveal the underlying structure of the semantic system. Primes were presented in the subjects' first language, while targets were in their second language. Priming effects were obtained for word pairs that were semantically highly similar but not translation equivalents, for example fence-haie (= hedge in French), suggesting that words in the two languages share common elements of semantic code. Priming was also obtained between translation equivalents which, in conjunction with the results for semantically similar pairs, is most naturally interpreted in terms of partially shared semantic representations. However, no masked priming effects were obtained between associated pairs of relatively low semantic similarity, for example shoe-pied (= foot in French), whereas such pairs did produce an effect when primes were unmasked. The results are discussed in terms of limitations on the semantic activation produced by masked words, and the role of collocational relationships in priming between associated words in the same language.     

Lexical processing in a non-native language: Effects of language proficiency and learning strategy

In three experiments, native Chinese speakers were asked to use their native and non-native languages to read and translate Chinese words and to name pictures. In Experiment 1, four groups of subjects with various degrees of proficiency in their second language, English, participated. In Experiments 2 and 3, subjects were first asked to learn a list of words in a new language, French, using either Chinese words or pictures as media; then they performed the reading, naming, and translation tasks. All subjects performed better in reading words than in naming pictures, when responding in Chinese. When the response was in the non-native language (English or French), high-learning subjects were equally efficient in translation and picture-naming tasks. Low-learning subjects, however, performed better in either the translation or the picture-naming task, depending on their learning strategies. These results are consistent with the idea that both proficiency in a non-native language and the strategy for acquiring the language are main determinants for the pattern of lexical processing in that language.     

Voluntary forgetting before and after learning has been accomplished

Two experiments, in which voluntary forgetting was measured, are reported. In both experiments, lists of randomly mixed syllables and numbers were projected on a screen, and Ss were instructed before projection which part of the lists to remember or to forget. In the first experiment, the syllables were cued as items to be forgotten in one group, and to be remembered in the other one. At the end of the projection, Ss were instructed to recall freely only the syllables. For the former group, this was an unexpected test. The same list was projected for different groups: one, three, five, seven, and fourteen times, with new randomly mixed items each time. Syllable recall increased with an increase of times of projection of the list in the second group, but not in the first one. Recall of syllables in the first group was, however, above the chance level. These results were best interpreted by assuming a voluntary forgetting mechanism, which operates after the verbal items leave the short term store. The second experiment, a variation of the first, was designed to find the locus of voluntary forgetting mechanisms. The question is whether Ss can voluntarily forget syllables only before they are learned, or also after learning has already taken place. Voluntary forgetting after learning has been achieved was found to be ineffective. These results tend to support the hypothesis that voluntary forgetting processes do not operate in the long-term store and that Ss can block the transmission of to be forgotten items from the short-term store to the long-term store.     

Inhibition, Contextual Segregation, and Subject Strategies in List Method Directed Forgetting

This experiment tested alternative explanations of list method directed forgetting effects. Two word lists were studied by 135 subjects. Between lists, subjects were instructed to remember both lists (remember group), remember both lists as well as in which list words were studied (segregate group), or to forget the first list and remember the second (forget group). All subjects took both recall and recognition tests with test order varied between subjects. Among subjects who took the recall test first, the forget group showed a directed forgetting effect (poorer performance on List 1 than List 2) with both recall accuracy, recall typing time, and recognition reaction time measures. Contextual segregation of List 1 words by forget subjects was ruled out as a sufficient cause of the effect. Limited support was obtained for a differential rehearsal explanation of the effect. Within-group comparisons and findings of release from directed forgetting support inhibitory processes as the major cause of the directed forgetting effect.     

Inhibiting retrieval of trauma cues in adults reporting histories of childhood sexual abuse

Are people who report having forgotten their childhood sexual abuse (CSA) characterised by superior ability to inhibit retrieval of disturbing material? To test this hypothesis, we asked adults reporting either repressed, recovered, or continuous memories of CSA or no history of CSA to participate in a directed forgetting experiment (list method). They rated the emotionality of two consecutive lists of trauma‐related and positive words. After the first list, the experimenter instructed participants to forget these words, and to continue rating the remaining words. A surprise recall task revealed robust directed forgetting and valence effects: All groups recalled more words from the second list than from the first list, and recalled more trauma words than positive ones. Participants reporting either repressed or recovered memories of CSA did not exhibit superior forgetting of trauma versus positive words relative to the other two groups. Finally, a subsidiary analysis revealed that participants exhibiting a “repressor” coping style (low self‐reported anxiety plus high defensiveness) did not exhibit superior directed forgetting of trauma words.     

Impaired directed forgetting in abstinent heroin addicts

Drug-related memories persist long into abstinence and are potent elicitors of drug craving and relapse. We report two experiments examining whether heroin-dependent individuals are impaired in intentionally suppressing drug-related memories. Experiment 1 adopted the Item paradigm where addicts and healthy controls were presented with a list of words each followed by a remember or forget cue. Experiment 2 adopted the List paradigm where they studied one list of items and were then split into a remember group and a forget group. Both groups studied a second list, except that the forget group was told to forget the first list. Compared with controls, addicts showed a reduced directed forgetting effect in the Item method and a total absence of one measure of directed forgetting in the List method (List 2 benefits). Results indicate that heroin addicts are impaired in directed forgetting and that the deficits are likely associated with memory encoding as opposed to retrieval. Possible problems include reduced ability in actively suppressing/stopping encoding of irrelevant information into memory or inability in changing/resetting encoding strategies. In neither experiment did the addicts show any differential directed forgetting effects between drug-related words and neutral words, indicating the generic nature of their intentional forgetting deficits.     

延时间隔和线索类型对遗忘学习判断的影响*

主要探讨不同延时间隔和线索类型对遗忘元认知判断的影响。采用传统的学习判断任务,让被试学习40对无意义配对词,并告知随后进行测试,当呈现第一个词时,被试能够回忆与之配对的后一个词。让被试预测当延迟不同时间（5分钟、1天和1周）进行测试时,他们能够记住（学习判断）或者遗忘（遗忘判断）后一词的可能性。最后,要求被试回忆所有词对。结果发现延时间隔对学习判断和遗忘判断有相似的影响;学习判断的等级和相对准确性均高于遗忘判断,说明人们对记住和遗忘的线索很敏感;相比于学习判断,人们监测自己遗忘能力的信心不足。研究结果表明人们能够利用延时间隔和线索类型来预测未来的测验成绩,对遗忘的监测能力低于对记住的监测。     

Time-dependent forgetting in visual short-term memory

ABSTRACT

Whether visual short-term memory can be lost over an unfilled delay, in line with time-dependent forgetting, is controversial and prior work has yielded mixed results. The present study explored time-dependent forgetting in visual short-term memory in relation to other factors. In three experiments, participants compared single target and probe objects over a 2 s or 10 s retention interval. The objects across trials were either similar or dissimilar (Experiment 1) and had to be remembered in the presence of an additional distractor (Experiment 2) or under conditions where the amount of time separating trials varied (Experiment 3). In all experiments, the retention interval manipulation made the biggest contribution to performance, with accuracy decreasing as the retention interval was lengthened from 2 s to 10 s. These results pose problems for interference and temporal distinctiveness models of memory but are compatible with temporal forgetting mechanisms such as decay.