短时记忆定向遗忘的负荷效应:来自ERP的证据

采用事件相关电位(ERPs)技术,通过一个短时记忆测试,考察记忆/遗忘线索在不同的工作记忆负荷条件下诱发的脑电差异。实验以字母和数字为刺激,要求被试记忆或遗忘不同数量的视觉信息。ERP结果发现:在线索呈现230~430ms的时间窗口,高负荷条件的遗忘线索比低负荷条件的遗忘线索诱发了更正的ERPs。这一结果表明,抑制机制在定向遗忘中有重要作用,抑制不同数量的信息需要不同数量的认知资源。     

定向遗忘的编码加工机制

有目的的遗忘(定向遗忘)需要耗费认知努力吗?有研究发现, 定向遗忘可能是被动衰减的结果, 即F项目(需要遗忘的项目)未获得有效复述是选择性复述了R项目(需要记住的项目)造成的, 这一加工过程不需要认知努力; 但也有研究表明, 定向遗忘过程可能是遗忘线索诱发的对记忆加工的主动抑制, 需要耗费认知努力, 脑认知研究中发现的前额叶ERPs成分为这一机制提供了证据。还有一种观点认为, 定向遗忘编码过程可能同时包含主动抑制与被动衰减, 但是尚不清楚两种加工机制相互作用的方式。为进一步澄清定向遗忘编码阶段的认知机制, 未来研究需要将非认知因素纳入考察, 并关注不同人群的定向遗忘特征, 在此基础上尝试解决理论争议。     

Directed forgetting in direct and indirect tests of memory: Seeking evidence of retrieval inhibition using electrophysiological measures

We investigated whether directed forgetting as elicited by the item-cueing method results solely from differential rehearsal of to-be-remembered vs. to-be-forgotten words or, additionally, from inhibitory processes that actively impair retrieval of to-be-forgotten words. During study, participants (N = 24) were instructed to remember half of a series of presented words (TBR) and to forget the other half (TBF), as indicated by an instruction cue shown shortly after each word. During test, accuracy and reaction time measures from lexical decisions (indirect memory test) followed by recognition-memory judgements (direct memory test) were supplemented with event-related potential (ERP) recordings. Results from the behavioural measures revealed directed forgetting in the recognition-memory test but not the lexical-decision test. ERPs obtained during recognition indicated that TBR words elicited a larger parietal old/new effect than TBF words overall, suggesting that remember/forget instructions impaired conscious recollection processes more severely than familiarity processes. Moreover, TBF words that were successfully forgotten elicited less parietal activity than correctly rejected new words (the reversed old/new effect; Nowicka, A., Jednorórog, K., Wypych, M., & Marchewka, A. (2009). Reversed old/new effect for intentionally forgotten words: An ERP study of directed forgetting. International Journal of Psychophysiology, 71, 97–102). This was taken to implicate that inhibitory processes likely affected these items. Enhanced negativities for successfully forgotten TBF words relative to new words were observed in the lexical-decision task at early (150–250 ms) and late (800–1000 ms) time windows, suggesting that inhibitory influences disrupt more than just conscious recollection when memory retrieval is tested indirectly.     

情绪一致性对有意遗忘的影响

有意遗忘是强调遗忘的有意性和指向性。对负性情绪的有意遗忘有利于个体的身心健康。本研究采用单字范式,实验一以正性、负性和中性情绪词为材料,探讨了情绪材料对有意遗忘的影响。结果发现,三类词语均表现出了显著的有意遗忘效应;实验二在实验一的基础上加入了情绪状态,探讨了情绪状态和情绪材料对有意遗忘的影响,结果发现,在积极情绪状态下,被试更多地遗忘负性情绪词;在消极情绪状态下,被试更多地遗忘中性词。表明个体对情绪信息的有意遗忘既受信息的情绪性影响,又受个体情绪状态的影响。     

The benefit of forgetting

Recent research using change-detection tasks has shown that a directed-forgetting cue, indicating that a subset of the information stored in memory can be forgotten, significantly benefits the other information stored in visual working memory. How do these directed-forgetting cues aid the memory representations that are retained? We addressed this question in the present study by using a recall paradigm to measure the nature of the retained memory representations. Our results demonstrated that a directed-forgetting cue leads to higher-fidelity representations of the remaining items and a lower probability of dropping these representations from memory. Next, we showed that this is made possible by the to-be-forgotten item being expelled from visual working memory following the cue, allowing maintenance mechanisms to be focused on only the items that remain in visual working memory. Thus, the present findings show that cues to forget benefit the remaining information in visual working memory by fundamentally improving their quality relative to conditions in which just as many items are encoded but no cue is provided.     

内容与自我关联性对负性情绪记忆定向遗忘的影响

本研究使用消极情绪视频片段作为实验材料,采用词表法定向遗忘范式,用2个实验分别考察了内容与自我关联性对负性情绪要义和细节记忆的定向遗忘及其权衡的影响。研究结果表明：(1)内容关联性对定向遗忘几乎没有影响,在内容关联条件下,遗忘提示只增加了要义记忆没有增加细节记忆;(2)自我关联性对定向遗忘产生了影响,自我关联条件下出现了定向遗忘,而自我无关条件下定向遗忘消失;(3) 关联性对细节和要义记忆有不同的影响,表现出明显的要义-细节权衡。     

“To‐be‐forgotten” statements become less true: Memory processes involved in selection and forgetting lead to truthfulness changes of ambiguous sentences

What happens when people try to forget something? What are the consequences of instructing people to intentionally forget a sentence? Recent studies employing the item‐method directed forgetting paradigm have shown that to‐be‐forgotten (TBF) items are, in a subsequent task, emotionally devaluated relative to to‐be‐remembered (TBR) items, an aftereffect of memory selection (Vivas, Marful, Panagiotidou & Bajo, 2016). As such, distractor devaluation by attentional selection generalizes to memory selection. In this study, we use the item‐method directed forgetting paradigm to test the effects of memory selection and inhibition on truth judgments of ambiguous sentences. We expected the relative standing of an item in the task (i.e., whether it was instructed to be remembered or forgotten) to affect the truthfulness value of that item, making TBF items less valid/truthful than TBR items. As predicted, ambiguous sentences associated with a “Forget” cue were subsequently judged as less true than sentences associated with a “Remember” cue, suggesting that instructions to intentionally forget a statement can produce changes in the validity/truthfulness of that statement. To our knowledge, this is the first study to show an influence of memory processes involved in selection and forgetting on the perceived truthfulness of sentences.     

Withdrawal of spatial overt attention following intentional forgetting: evidence from eye movements

Eye movements were measured to examine whether item-method directed forgetting involved a spatial overt attention shift. Experiment 1 showed that participants’ eyes were moved away from the study word following the forget and ignore cues, but not the remember cue. Experiment 2 revealed that the eyes were moved away from the area that covered by the study word even when the study word disappeared upon the presentation of the memory cue. Both the study word and memory cue were presented auditorily in Experiment 3. In all experiments, the to-be-remembered words were recalled better than both to-be-forgotten and to-be-ignored words. More importantly, mental effort, as indexed by the pupil size, increased following the remember, as compared with the forget and ignore cues. These findings are discussed in terms of controlling spatial overt attention after encoding to withdraw attention from irrelevant information and to allocate cognitive resources to relevant information for long-term retention.     

负性情绪材料的定向遗忘及心理机制

采用项目法定向遗忘的研究范式,在两个实验中分别采用文字和图片材料考察了情绪性记忆定向遗忘的效果及其心理机制。实验中采用了中性和负性两种实验材料,设置了两种记忆指令出现时间（2秒后提示和5秒后提示）,相对于中性材料,被试更不容易忘记负性材料。记忆指令出现的时间只影响图片材料的定向遗忘。研究表明负性情绪会干扰定向遗忘,选择性编码理论可以解释情绪性文字材料的定向遗忘,而抑制理论更能解释情绪性图片材料的定向遗忘效应。     

两种范式下有意遗忘的实验研究

本文以英语词汇为材料,采用自由回忆和再认测验作为外显记忆测验,词干补笔测验作为内隐记忆测验,探讨小学五年级学生在单字范式与字表范式下的有意遗忘效应及其机制。结果发现:(1)单字范式下,三种测验中都存在有意遗忘效应;而字表范式下,只有词干补笔和自由回忆测验中存在有意遗忘效应;(2)三种测验中,单字范式下记忆项与遗忘项的差异显著高于字表范式下二者的差异。这表明,两种范式下有意遗忘效应产生的机制是不一致的,且相较于字表范式,单字范式下有意遗忘效应更显著。     

Remembering what one intended to forget: the lack of directed forgetting effects in implicit memory

The results of previous studies on directed forgetting effects in implicit memory have led to the conclusion that the underlying mechanism for such effects is an inhibition of retrieval or an encoding difficulty. Differences in procedure and stimuli may contribute to these different conclusions. In 2 studies we standardized the procedure while varying the stimuli. As in previous research, directed forgetting results were obtained for direct memory tasks. However, the magnitude of the directed forgetting effect varied with the stimuli. In Experiments 1 and 2, medium- and low-frequency to-be-remembered (R) and to-be-forgotten (F) words appeared to be equally accessible using the indirect task. In Experiment 3, we devised a procedure in which a single stem could lead to an R-word or F-word, but space was provided for only one word. In that way, we could examine the relative accessibility of R- and F-words. Results are discussed in light of Mandler's (1980) conceptualization of the contributions of identification and familiarity to memory retrieval processes.     

Memory and conceptual learning of relevant and non-relevant items in item-method directed forgetting

The present research investigates the fate of non-target information when people are trying to either intentionally memorise or forget target information. By using an object-based attentional manipulation within a directed forgetting paradigm (item-method), we show a directed forgetting effect (DFE, i.e., better memory for to-be-remembered (TBR) than for to-be-forgotten (TBF) items) for items that participants are explicitly instructed to attend but not for irrelevant items that happen to be part of the context. Alongside the classic DFE, we investigate how the category of the attended and unattended items are learned. The results obtained in three experiments, show that people can successfully learn only the category of the TBR attended items and that the DFE extends to new items that are related to the old TBR and TBF items (an effect that we call conceptual DFE). These results give us new insight about how TBR and TBF items are processed and conceptually learned.     

Ontogeny of early event memory: I. Forgetting and retrieval by 2- and 3-month-olds

In 2 experiments, 2-month-olds, trained in the mobile conjugate reinforcement paradigm for two daily sessions, showed retrieval deficits relative to 3-month-olds. In Experiment 1, tests of simple forgetting administered to 2-month-olds after retention intervals of 1, 3, 6, and 9 days (a period over which 3-month-olds remember the contingency) indicated that their forgetting was complete after delays greater than 1 day. In Experiment 2, reactivation treatments administered to 2- and 3-month-olds alleviated forgetting after a retention interval of 28, but not 35, days in the 3-month-old group only. Previously, alleviated forgetting by a reactivation treatment had been demonstrated in 2-month-olds after a delay of 18 days. In both of the present experiments, performance of the two age groups did not differ during the immediate retention test at the end of training. These results suggest that neither the age of the infant nor the age of the memory determines memory retrieval after long delays; instead, it appears to be determined by the length of time that a memory has been inaccessible (i.e., forgotten). We propose that factors which delay simple forgetting will correspondingly increase the length of the interval over which a retrieval cue can still be effective in a reactivation paradigm, irrespective of the age of the infant or the age of the memory.     

Directed forgetting of complex pictures in an item method paradigm

An item-cued directed forgetting paradigm was used to investigate the ability to control episodic memory and selectively encode complex coloured pictures. A series of photographs was presented to 21 participants who were instructed to either remember or forget each picture after it was presented. Memory performance was later tested with a recognition task where all presented items had to be retrieved, regardless of the initial instructions. A directed forgetting effect—that is, better recognition of “to-be-remembered” than of “to-be-forgotten” pictures—was observed, although its size was smaller than previously reported for words or line drawings. The magnitude of the directed forgetting effect correlated negatively with participants’ depression and dissociation scores. The results indicate that, at least in an item method, directed forgetting occurs for complex pictures as well as words and simple line drawings. Furthermore, people with higher levels of dissociative or depressive symptoms exhibit altered memory encoding patterns.     

情绪性记忆的定向遗忘效应

刺激的情绪性具有增强记忆的效果,那么,带有情绪信息的刺激对遗忘又会产生怎样的影响？已有研究从行为及认知神经机制层面探讨了情绪性刺激对定向遗忘效应的影响,但结果并不一致。总结已有文献发现,以情绪性刺激的材料类型、情绪效价、唤醒度和熟悉度为主的客观因素和以被试的情绪状态为主的主观因素均为影响定向遗忘效应产生及其稳定性的重要原因。这类研究是对有意遗忘研究领域的重要补充,也加深了人们对有意遗忘机制的理解。     

The effect of neutral and negative colour photographs on children's item directed forgetting

Intentional forgetting is an active process relying on cognitive mechanisms (e.g., rehearsal strategies and inhibition) developing during the elementary school years. Colour photographs might be rehearsed differently in memory than words, and therefore result in a different developmental pattern of intentional forgetting than previously acknowledged. Moreover, negative material is thought to be particularly reliant upon inhibitory mechanisms in order not to be encoded in memory. Thus, children's item-directed forgetting (DF) might develop differently both in relation to colour photographs in general and for negative pictorial stimuli in particular. The aim of the present study was to investigate item DF for colour photographs of neutral and negative valence in sixty-five school-aged children (8–12 years of age). In the present study, a DF effect was revealed irrespective of age for neutral images as well as negative images. Results are discussed in relation to potential mechanisms underlying item DF for colour photographs and how these affect development of intentional forgetting.     

Memory awareness following episodic inhibition

Three experiments used directed forgetting (DF) and retrieval practice (RP) to investigate the relation of inhibited items to states of memory awareness occurring at test. In Experiment 1 using list DF robust inhibitory effects were present in cued recall, but in a recognition test these effects were only present in responses accompanied by recollective experience. In Experiments 2 and 3 using RP reliable effects of inhibition were found but these did not relate systematically to states of memory awareness. It is suggested that in DF the to-be-forgotten items are tagged at study as not to be recollectively experienced and so have a specific, inhibitory, relation to states of recollective experience occurring during test. In RP no tagging takes place, and inhibition is automatic or nonintentional and consequently does not have a specific relation to states of memory awareness at test.     

Memory awareness following episodic inhibition

Three experiments used directed forgetting (DF) and retrieval practice (RP) to investigate the relation of inhibited items to states of memory awareness occurring at test. In Experiment 1 using list DF robust inhibitory effects were present in cued recall, but in a recognition test these effects were only present in responses accompanied by recollective experience. In Experiments 2 and 3 using RP reliable effects of inhibition were found but these did not relate systematically to states of memory awareness. It is suggested that in DF the to-be-forgotten items are tagged at study as not to be recollectively experienced and so have a specific, inhibitory, relation to states of recollective experience occurring during test. In RP no tagging takes place, and inhibition is automatic or nonintentional and consequently does not have a specific relation to states of memory awareness at test.     

Directed Forgetting and Aging: The Role of Retrieval Processes,Processing Speed,and Proactive Interference

ABSTRACT

The directed forgetting effect obtained with the item method is supposed to depend on both selective rehearsal of to-be-remembered (TBR) items and attentional inhibition of to-be-forgotten (TBF) items. In this study, we investigated the locus of the directed forgetting deficit in older adults by exploring the influence of recollection and familiarity-based retrieval processes on age-related differences in directed forgetting. Moreover, we explored the influence of processing speed, short-term memory capacity, thought suppression tendencies, and sensitivity to proactive interference on performance. The results indicated that older adults' directed forgetting difficulties are due to decreased recollection of TBR items, associated with increased automatic retrieval of TBF items. Moreover, processing speed and proactive interference appeared to be responsible for the decreased recall of TBR items.     

情绪对连续事件定向遗忘的影响

本研究采用项目法定向遗忘范式以中性和负性连续事件的视频为实验材料, 通过2个实验考察了情绪对连续事件定向遗忘的影响, 并进一步探讨了情绪对细节记忆和要义记忆的定向遗忘的影响。结果发现, 情绪可以消除细节记忆的定向遗忘效应, 而仅有要义记忆的定向遗忘效应则主要受到事件连续性而非情绪的影响。