Modulation of retrieval processing reflects accuracy of emotional source memory

There is considerable evidence that encoding and consolidation of memory are modulated by emotion, but the retrieval of emotional memories is not well characterized. Here we manipulated the emotional context with which affectively neutral stimuli were associated during encoding, allowing us to examine neural activity associated with retrieval of emotional memories without confounding the emotional attributes of cue items and the retrieved context. Using a source memory procedure we were also able to compare how retrieval processing was modulated when the emotional encoding context was recollected or not. An interaction between emotional encoding context and accuracy of source memory revealed that successful retrieval of emotional context was associated with activity in left amygdala, and a left frontotemporal network including anterior insula, prefrontal cortex and cingulate. In contrast, when contextual retrieval was unsuccessful, items encoded in emotional contexts elicited enhanced activity in right amygdala and a right-lateralized network that included extrastriate visual areas. These findings indicate distinct effects of emotion on successful and unsuccessful retrieval of source information, including lateralization of amygdala responses.     

Angry expressions strengthen the encoding and maintenance of face identity representations in visual working memory

Visual working memory (WM) for face identities is enhanced when faces express negative versus positive emotion. To determine the stage at which emotion exerts its influence on memory for person information, we isolated expression (angry/happy) to the encoding phase (Experiment 1; neutral test faces) or retrieval phase (Experiment 2; neutral study faces). WM was only enhanced by anger when expression was present at encoding, suggesting that retrieval mechanisms are not influenced by emotional expression. To examine whether emotional information is discarded on completion of encoding or sustained in WM, in Experiment 3 an emotional word categorisation task was inserted into the maintenance interval. Emotional congruence between word and face supported memory for angry but not for happy faces, suggesting that negative emotional information is preferentially sustained during WM maintenance. Our findings demonstrate that negative expressions exert sustained and beneficial effects on WM for faces that extend beyond encoding.     

记忆编码中目标与背景的情绪一致性对记忆提取的影响

摘 要 本研究将经典情绪启动范式和学习-再认范式相结合,探讨学习时启动与目标的情绪一致性对目标再认的影响。在记忆编码阶段,以情绪面孔图片为启动刺激、一般情绪图片为目标刺激,要求被试对目标图片的效价进行判断;在提取阶段向被试呈现一般情绪图片,要求被试判断是否在前一阶段见过。结果表明,编码阶段的加工背景对记忆提取产生了显著影响。一致启动促进了认知加工与记忆编码,提高了再认正确率。ERP结果也表明,在目标刺激呈现后300-500ms,编码时的情绪一致性对再认阶段消极目标诱发的ERP产生了显著影响。     

Positive emotion can protect against source memory impairment

Despite widespread belief that memory is enhanced by emotion, evidence also suggests that emotion can impair memory. Here we test predictions inspired by object-based binding theory, which states that memory enhancement or impairment depends on the nature of the information to be retrieved. We investigated emotional memory in the context of source retrieval, using images of scenes that were negative, neutral or positive in valence. At study each scene was paired with a colour and during retrieval participants reported the source colour for recognised scenes. Critically, we isolated effects of valence by equating stimulus arousal across conditions. In Experiment 1 colour borders surrounded scenes at study: memory impairment was found for both negative and positive scenes. Experiment 2 used colours superimposed over scenes at study: valence affected source retrieval, with memory impairment for negative scenes only. These findings challenge current theories of emotional memory by showing that emotion can impair memory for both intrinsic and extrinsic source information, even when arousal is equated between emotional and neutral stimuli, and by dissociating the effects of positive and negative emotion on episodic memory retrieval.     

Residual effects of emotion are reflected in enhanced visual activity after sleep

Research has investigated how sleep affects emotional memory and how emotion enhances visual processing, but these questions are typically asked by re-presenting an emotional stimulus at retrieval. For the first time, we investigate whether sleep affects neural activity during retrieval when the memory cue is a neutral context that was previously presented with either emotional or nonemotional content during encoding. Participants encoded scenes composed of a negative or neutral object on a neutral background either in the morning (preceding 12 hours awake; wake group) or evening (preceding 12 hours including a night of sleep; sleep group). At retrieval, participants viewed the backgrounds without their objects, distinguishing new backgrounds from those previously studied. Occipital activity was greater within the sleep group than the wake group specifically during the successful retrieval of neutral backgrounds that had been studied with negative (but not neutral) objects. Moreover, there was enhanced connectivity between the middle occipital gyrus and hippocampus following sleep. Within the sleep group, the percentage of REM sleep obtained correlated with activity in the middle occipital gyrus, lingual gyrus, and cuneus during the successful retrieval of neutral backgrounds previously paired with negative objects. These results confirm that emotion affects neural activity during retrieval even when the cues themselves are neutral, and demonstrate, for the first time, that this residual effect of emotion on visual activity is greater after sleep and may be maximized by REM sleep.     

回忆任务对合作抑制和错误修剪的调节——情绪效价和编码水平的影响

前人在项目回忆条件的合作记忆研究中记录到明显的合作抑制和错误修剪,背景提取条件的相关研究尤显不足;同时,情绪效价和编码水平对两类现象调节的研究尚未涉及。为此,本文在两个实验中采用经典合作记忆研究范式,以不同情绪效价的词汇为实验材料并以词汇在学习阶段的呈现颜色为背景展开研究。实验1和实验2分别在学习阶段采用了深编码和浅编码任务,回忆阶段则均含项目回忆(回忆已学词汇)和背景提取(回忆词汇在学习阶段的呈现颜色)两种任务。采用深编码条件的实验1的结果显示,项目回忆比背景提取条件的合作抑制更强、错误修剪更弱,回忆任务与词汇情绪效价交互影响合作抑制强度;采用浅编码条件的实验2则发现错误修剪在两种任务间的差异不显著。两实验的联合分析显示,回忆任务与编码水平交互影响合作抑制和错误修剪强度。上述结果表明:回忆任务对合作抑制和错误修剪的调节支持双重加工模型;回忆任务与情绪效价对合作抑制强度的交互影响支持权衡说,且与双重加工模型相吻合;回忆任务与编码水平交互影响合作抑制和错误修剪强度。     

Emotional enhancement of immediate memory: Positive pictorial stimuli are better recognized than neutral or negative pictorial stimuli

We examined emotional memory enhancement (EEM) for negative and positive pictures while manipulating encoding and retrieval conditions. Two groups of 40 participants took part in this study. Both groups performed immediate implicit (categorization task) and explicit (recognition task) retrieval, but for one group the tasks were preceded by incidental encoding and for the other group by intentional encoding. As indicated by the sensitivity index (d'), after incidental encoding positive stimuli were easier to recognize than negative and neutral stimuli. Participants' response criterion was more liberal for negative stimuli than for both positive and neutral ones, independent of encoding condition. In the implicit retrieval task, participants were slower in categorizing positive than negative and neutral stimuli. However, the priming effect was larger for emotional than for neutral stimuli. These results are discussed in the context of the idea that the effect of emotion on immediate memory enhancement may depend on the intentionality to encode and retrieve information.     

Variations in constrained retrieval

Mentally reinstating encoding operations at retrieval might improve access to memories; however, such constrained retrieval is an effortful process that may not always be used. The memory-for-foils procedure (Jacoby, Shimizu, Daniels, & Rhodes, Psychonomic Bulletin & Review 12, 852-857, 2005) infers participant-initiated mental reinstatement of encoding operations during attempts at recognition from the differential memory that accrues to foils during a test of deeply processed items versus during a test of shallowly processed items, as indicated by performance on a final recognition memory test for the foils. Experiment 1 tested whether differential memory for foils is due to the evocation of task context during recollection of neighboring old items. Experiment 2 tested whether inducing a set to respond without much effort on a prior recognition test affects the likelihood of constrained retrieval on later tests. Experiment 3 tested whether constrained retrieval is less likely to occur when the deep versus shallow source of test items is intermixed, rather than blocked in separate tests. These experiments provide evidence that people query memory by mentally reinstating encoding operations and identify conditions that affect the probability of constrained retrieval.     

不同情绪背景下来源记忆的ERPs研究*

使用事件相关电位(ERP)技术和测试来源记忆的多键范式,探讨不同情绪效价背景下来源提取的认知神经机制。学习阶段,同时呈现汉字和3种效价情绪图片(重叠);测验阶段,只呈现汉字,要求被试进行四键判断：旧字且背景为中性,旧字且背景为正性,旧字且背景为负性,新字。结果发现：在提取阶段,刺激呈现后300~500 ms,3种情绪背景下来源判断正确项目和来源判断错误项目都比新项目诱发了更正的ERPs(即都存在新旧效应),这一结果反映出刺激呈现后300~500 ms 是一个早期的项目提取阶段,它独立于来源提取。并且,在中性背景下,两种新旧效应没有差别;而在正性和负性背景下,来源判断正确项目的新旧效应显著大于来源判断错误项目。说明相比于中性背景,情绪背景下被试可能更早对来源信息产生熟悉感。在500~650 ms,3种情绪背景下都存在来源判断正确项目的新旧效应,在来源判断错误项目和新项目之间没有显著差异,来源正确与来源错误有显著的新旧效应差异,但二者在头皮分布上是类似的,这反映了晚期的来源提取过程。同时来源正确的新旧效应在这两个时段有显著不同的头皮分布,表明这两个时段有不同加工过程。另外,在500~650 ms,存在显著的情绪效应,正性背景下正确判断来源诱发的ERPs比中性和负性背景下的更正,而且来源判断错误条件下没有情绪效应。综上所述,来源正确和来源错误可能仅仅反映了大脑激活在量上的不同,并不能推断两者存在质的差异;大脑神经活动的早期不仅反映了对记忆项目的熟悉性,而且也受情绪效应的影响,500 ms之后大脑神经活动反映的是对记忆项目回想的过程,这一回想过程也与情绪效应有关,受到情绪效应的调节。     

自传体记忆的情绪对其相关信息内隐提取的影响

本研究主要考察自传体记忆本身的情绪是否影响该记忆相关信息的内隐提取过程。取大学生15人完成实验, 实验分为两部分：记忆提取和词汇判断。首先在记忆提取阶段, 要求被试根据词对(形容词-中性名词)提取积极、消极和中性情绪色彩的自传体记忆事件。接着在词汇判断任务中, 要求被试对包含提取过记忆的中性名词的词语进行词和非词的判断, 并且记录相应的脑电波。结果发现：(1)被试按要求成功提取了积极、消极和中性三类自传体记忆事件。词汇判断任务中, 内隐提取三类自传体记忆信息的反应时和正确率均无显著差异。(2)相比于积极、中性自传体记忆信息, 消极自传体记忆信息提取的过程中的ERP波幅更大, 更偏向于正向。这表明自传体记忆信息的内隐提取受到记忆本身情绪的影响, 消极自传体记忆信息提取需要付出更多资源。     

Binding neutral information to emotional contexts: Brain dynamics of long-term recognition memory

There is abundant evidence in memory research that emotional stimuli are better remembered than neutral stimuli. However, effects of an emotionally charged context on memory for associated neutral elements is also important, particularly in trauma and stress-related disorders, where strong memories are often activated by neutral cues due to their emotional associations. In the present study, we used event-related potentials (ERPs) to investigate long-term recognition memory (1-week delay) for neutral objects that had been paired with emotionally arousing or neutral scenes during encoding. Context effects were clearly evident in the ERPs: An early frontal ERP old/new difference (300–500 ms) was enhanced for objects encoded in unpleasant compared to pleasant and neutral contexts; and a late central-parietal old/new difference (400–700 ms) was observed for objects paired with both pleasant and unpleasant contexts but not for items paired with neutral backgrounds. Interestingly, objects encoded in emotional contexts (and novel objects) also prompted an enhanced frontal early (180–220 ms) positivity compared to objects paired with neutral scenes indicating early perceptual significance. The present data suggest that emotional—particularly unpleasant—backgrounds strengthen memory for items encountered within these contexts and engage automatic and explicit recognition processes. These results could help in understanding binding mechanisms involved in the activation of trauma-related memories by neutral cues.     

Working memory affects false memory production for emotional events

Whereas a link between working memory (WM) and memory distortions has been demonstrated, its influence on emotional false memories is unclear. In two experiments, a verbal WM task and a false memory paradigm for negative, positive or neutral events were employed. In Experiment 1, we investigated individual differences in verbal WM and found that the interaction between valence and WM predicted false recognition, with negative and positive material protecting high WM individuals against false remembering; the beneficial effect of negative material disappeared in low WM participants. In Experiment 2, we lowered the WM capacity of half of the participants with a double task request, which led to an overall increase in false memories; furthermore, consistent with Experiment 1, the increase in negative false memories was larger than that of neutral or positive ones. It is concluded that WM plays a critical role in determining false memory production, specifically influencing the processing of negative material.     

Retrieval‐induced forgetting of emotional and unemotional autobiographical memories

This experiment extended the retrieval‐induced forgetting (RIF) procedure from simple, episodic information to emotional and unemotional autobiographical memories. In the elicitation phase, participants generated specific memories from their past in response to negative, neutral, or positive category cues. In the retrieval‐practice phase, they practised retrieving (and elaborated further on) some of the memories for some of the categories. In the final test phase, they tried to recall all memories. Memories that received retrieval practice were recalled more often on final test than baseline memories, whereas memories that were not practised, yet competed with practised memories via a shared category cue, were recalled less often than baseline memories. We discuss the roles of inhibition, competition, emotion, and self‐relevance, and consider what laboratory manipulations of memory might reveal about everyday and pathological personal memory.     

情绪效价的记忆增强效应:存储或提取优势?

情绪效价和情绪唤醒是描述情绪的两个维度。情绪增强记忆效应表明情绪唤醒事件的记忆往往优于非情绪唤醒事件的记忆,但关于积极情绪记忆和消极情绪记忆哪个在记忆中处于优势仍存在争论。实验以情绪词对和中性词对为实验材料。实验一探讨积极情绪词语或消极情绪词语的记忆优势; 实验二探讨积极情绪环境或消极情绪环境中中性词语的记忆优势。在两种实验条件下,积极情绪下的自由回忆都优于消极情绪下的自由回忆; 多项加工树的存储—提取模型使用实验自由回忆和线索回忆的结果将记忆的存储和提取优势分离开来,结果表明:积极情绪事件记忆优势发生在存储阶段,而积极情绪环境记忆优势发生在存储和提取阶段; 积极情绪事件记忆偏向支持“刺激后编码增强假设”,积极情绪环境记忆偏向支持“唤醒—偏向竞争假设”。     

词语后情绪环境对语义和感知加工的影响

词语后情绪环境对其中的事件记忆产生影响,但是事件后情绪环境如何影响记忆加工仍不清楚。不同的情绪环境理论—“唤醒偏向竞争理论”,“拓宽-建构理论”,“记忆中心的积极情绪促进理论”支持情绪促进的不同本质。已有的研究表明,注意在情绪记忆中有重要作用。实验一、实验二分别探讨词语后情绪环境对其语义加工与内源源加工和外源源加工的影响。与中性环境相比,积极与消极情绪环境阻碍了外源源特征的加工; 与中性环境和积极情绪环境相比,消极情绪环境阻碍了内源源特征的加工。实验结果支持“唤醒偏向竞争理论”,同时表明“评估”和“注意放置”在情绪环境影响中的重要作用。     

Lateral and medial prefrontal contributions to emotion generation by semantic elaboration during episodic encoding

Memories for emotion-laden stimuli are remembered more accurately than those for neutral stimuli. Although this enhancement reflects stimulus-driven modulation of memory by emotions, functional neuroimaging evidence of the interacting mechanisms between emotions generated by intentional processes, such as semantic elaboration, and memory is scarce. The present fMRI study investigated how encoding-related activation is modulated by emotions generated during the process of semantic elaboration. During encoding with fMRI, healthy young adults viewed neutral (target) pictures either passively or with semantic elaboration. In semantic elaboration, participants imagined background stories related to the pictures. Encoding trials with semantic elaboration were subdivided into conditions in which participants imagined negative, positive, or neutral stories. One week later, memories for target pictures were tested. In behavioral results, memories for target pictures were significantly enhanced by semantic elaboration, compared to passive viewing, and the memory enhancement was more remarkable when negative or positive stories were imagined. fMRI results demonstrated that activations in the left inferior frontal gyrus and dorsal medial prefrontal cortex (dmPFC) were greater during the encoding of target pictures with semantic elaboration than those with passive viewing, and that these activations further increased during encoding with semantic elaboration of emotional stories than of neutral stories. Functional connectivity between the left inferior frontal gyrus and dmPFC/hippocampus during encoding significantly predicted retrieval accuracies of memories encoded with self-generated emotional stories. These findings suggest that networks including the left inferior frontal region, dmPFC, and hippocampus could contribute to the modulation of memories encoded with the emotion generation.     

Motor action and emotional memory

Can simple motor actions affect how efficiently people retrieve emotional memories, and influence what they choose to remember? In Experiment 1, participants were prompted to retell autobiographical memories with either positive or negative valence, while moving marbles either upward or downward. They retrieved memories faster when the direction of movement was congruent with the valence of the memory (upward for positive, downward for negative memories). Given neutral-valence prompts in Experiment 2, participants retrieved more positive memories when instructed to move marbles up, and more negative memories when instructed to move them down, demonstrating a causal link from motion to emotion. Results suggest that positive and negative life experiences are implicitly associated with schematic representations of upward and downward motion, consistent with theories of metaphorical mental representation. Beyond influencing the efficiency of memory retrieval, the direction of irrelevant, repetitive motor actions can also partly determine the emotional content of the memories people retrieve: moving marbles upward (an ostensibly meaningless action) can cause people to think more positive thoughts.     

Post-encoding emotional arousal enhances consolidation of item memory,but not reality-monitoring source memory

The current study examined whether the effect of post-encoding emotional arousal on item memory extends to reality-monitoring source memory and, if so, whether the effect depends on emotionality of learning stimuli and testing format. In Experiment 1, participants encoded neutral words and imagined or viewed their corresponding object pictures. Then they watched a neutral, positive, or negative video. The 24-hour delayed test showed that emotional arousal had little effect on both item memory and reality-monitoring source memory. Experiment 2 was similar except that participants encoded neutral, positive, and negative words and imagined or viewed their corresponding object pictures. The results showed that positive and negative emotional arousal induced after encoding enhanced consolidation of item memory, but not reality-monitoring source memory, regardless of emotionality of learning stimuli. Experiment 3, identical to Experiment 2 except that participants were tested only on source memory for all the encoded items, still showed that post-encoding emotional arousal had little effect on consolidation of reality-monitoring source memory. Taken together, regardless of emotionality of learning stimuli and regardless of testing format of source memory (conjunction test vs. independent test), the facilitatory effect of post-encoding emotional arousal on item memory does not generalize to reality-monitoring source memory.     

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。