Context-dependent repetition effects on recognition memory

One widely acknowledged way to improve our memory performance is to repeatedly study the to be learned material. One aspect that has received little attention in past research regards the context sensitivity of this repetition effect, that is whether the item is repeated within the same or within different contexts. The predictions of a neuro-computational model (O’Reilly & Norman, 2002) were tested in an experiment requiring participants to study visual objects either once or three times. Crucially, for half of the repeated objects the study context (encoding task, background color and screen position) remained the same (within context repetition) while for the other half the contextual features changed across repetitions (across context repetition). In addition to behavioral measures, event-related potentials (ERP) were recorded that provide complementary information on the underlying neural mechanisms during recognition. Consistent with dual-process models behavioral estimates (remember/know-procedure) demonstrate differential effects of context on memory performance, namely that recognition judgements were more dependent on familiarity when repetition occurs across contexts. In accordance with these behavioral results ERPs showed a larger early frontal old/new effect for across context repetitions as compared to within context repetitions and single presentations, i.e. an increase in familiarity following repetition across study contexts. In contrast, the late parietal old/new effect, indexing recollection did not differ between both repetition conditions. These results suggest that repetition differentially affects familiarity depending on whether it occurs within the same context or across different contexts.     

The effects of age on the neural correlates of successful episodic retrieval: An ERP study

The neural correlates of successful episodic retrieval (recollection), as reflected in event-related potentials (ERPs), were investigated in young (ca. 20 years; n=18) and older (ca. 70 years; n=16) healthy individuals. Subjects classified a series of pictures according to whether each item was new or had been encountered at study in the context of an animacy or a size judgment task. By manipulating the number of times items were presented for study, subsets of test items were formed for which source accuracy did not differ according to age. Relative to ERPs elicited by unstudied pictures, ERPs elicited by items attracting equivalent levels of source accuracy showed marked age-related differences. Those from younger subjects demonstrated the positive-going left parietal and right frontal old/new effects described in several previous studies of source memory. By contrast, analogous ERPs from older subjects contained a large left-lateralized negative effect that overshadowed the positive-going effects evident in the young. No age-related differences in either parietal or frontal ERP old/new effects were detected at electrode sites overlying the right hemisphere. It is possible that the age-related ERP differences observed in this task primarily reflect the use of different kinds of information as a basis for source judgments.     

Age-related differences in brain electrical activity during extended continuous face recognition in younger children, older children and adults

To examine the development of recognition memory in primary-school children, 36 healthy younger children (8-9 years old) and 36 healthy older children (11-12 years old) participated in an ERP study with an extended continuous face recognition task (Study 1). Each face of a series of 30 faces was shown randomly six times interspersed with distracter faces. The children were required to make old vs. new decisions. Older children responded faster than younger children, but younger children exhibited a steeper decrease in latencies across the five repetitions. Older children exhibited better accuracy for new faces, but there were no age differences in recognition accuracy for repeated faces. For the N2, N400 and late positive complex (LPC), we analyzed the old/new effects (repetition 1 vs. new presentation) and the extended repetition effects (repetitions 1 through 5). Compared to older children, younger children exhibited larger frontocentral N2 and N400 old/new effects. For extended face repetitions, negativity of the N2 and N400 decreased in a linear fashion in both age groups. For the LPC, an ERP component thought to reflect recollection, no significant old/new or extended repetition effects were found. Employing the same face recognition paradigm in 20 adults (Study 2), we found a significant N400 old/new effect at lateral frontal sites and a significant LPC repetition effect at parietal sites, with LPC amplitudes increasing linearly with the number of repetitions. This study clearly demonstrates differential developmental courses for the N400 and LPC pertaining to recognition memory for faces. It is concluded that face recognition in children is mediated by early and probably more automatic than conscious recognition processes. In adults, the LPC extended repetition effect indicates that adult face recognition memory is related to a conscious and graded recollection process rather than to an automatic recognition process.     

Age-related differences in familiarity and recollection: ERP evidence from a recognition memory study in children and young adults

Using event-related potentials (ERPs), we examined the relative contributions of familiarity and recollection to recognition memory for items and their study contexts in school-aged children and adults. Whereas adults were able to selectively accept target items and to reject familiar nontarget items in an exclusion task, this discrimination was more difficult for children, as was evident in the high false alarm rates to nontargets even when item memory was controlled for. The analysis of the adults’ ERPs revealed more flexible and task-appropriate retrieval mechanisms, as was evident in the correlates of familiarity, recollection, and nontarget retrieval, as well as in postretrieval evaluation. In contrast, children’s ERPs revealed a parietal old/new effect for targets taken as a putative correlate of recollection. These findings suggest that children rely predominantly on recollection during recognition judgments, even in the absence of efficient memory control processes. The latter processes enable adults to monitor and verify the retrieved information and to control nontarget retrieval in the service of adequate source memory performance.     

An Event-Related Potential Study of Item Recognition Memory in Children and Adults

The purpose of this study was to contrast children's event-related potentials (ERPs) with those of adults in an item recognition memory task. Four-year-old children and adults were presented with pictorial images, one half of which had been previously shown, and were asked to indicate whether each picture had been seen before. In both samples, an old-new effect was found in the ERP, namely that responses to correctly recognized old pictures elicited more positive-going ERPs than responses to correctly rejected new pictures. However, there were differences between adults' and children's ERPs with respect to the asymmetric scalp distribution and the time course of the old-new difference. In adults, the ERP differences between old and new pictures were bilateral, whereas in children the differences had a tendency to be stronger over the right hemisphere. In addition, children's ERP effects for correct discrimination between old and new pictures began around 400 to 500 msec later than it did in adults. The similarities and differences between the child and adult findings are discussed in terms of developmental changes in cognitive abilities that may be mirrored through corresponding changes in ERPs.     

跨领域项目间联结记忆中项目提取和关系提取的分离：一项事件相关电位研究

使用ERPs技术, 探讨跨领域项目间联结记忆中项目提取和关系提取的差异。学习阶段, 系列呈现面孔-事件动词材料, 让被试识记面孔、事件动词以及两者之间的关系; 测验阶段, 要求被试对成对刺激进行“相同”、“重组”或“新”判断。结果发现：提取阶段, 刺激呈现后约200 ms, “相同”、“重组”和“新”3种条件下的ERPs开始出现分离, 存在“相同/新”、“重组/新”和“相同/重组”三类新旧效应。在200~300 ms, “相同/新”和“重组/新”两类新旧效应表现在前额和额区皮层; 在300~500 ms, 这两类新旧效应广泛地分布在从前到后各个脑区皮层; 在500~700 ms, “相同/新”新旧效应出现在额-顶区皮层, 而无“重组/新”新旧效应; 在700~1400 ms, 这两类新旧效应发生在前额和额区皮层; 在上述4个时段, “相同/重组”关系新旧效应都发生在额中-中央-顶区皮层。从这些结果可以推知：跨领域项目间联结再认中, 项目新旧效应和关系新旧效应同时出现, 但是关系提取比项目提取较晚完成; 额中-中央-顶区皮层关系新旧效应反映了对项目间关系的回忆加工; 而700 ms以后, 前额、额区皮层新旧效应可能反映了项目之间关系提取过程的执行加工功能。     

汉词和图画再认的ERP效应及脑机制

目的：比较汉词与图画材料再认过程中的事件相关电位（ERP）表现并探讨其脑机制。方法：使用经典“学习一再认”实验模式对21名大学生进行测验,同时记录EEG,离线处理后对汉词及图画再认诱发的ERP波形主要成分及新旧效应进行比较。结果：两种材料的再认均诱发出了明显的新旧效应。顶区新旧效应头皮分布基本一致,但图画再认该效应波幅大于汉词再认;两种材料诱发的额区新旧效应有所不同,图画再认该效应为正走向,而汉词再认此效应表现为负走向趋势。结论：汉词与图画再认既存在某种共同的神经加工机制,叉分别涉及一些特异性的神经活动模式。     

内隐重复效应影响外显工作记忆的年龄差异

采用延迟样本匹配任务并控制被试对部分项目的有意识学习经验, 当前研究考察了老年被试与青年被试在追逐靶、排除分心物的过程中, 重复启动效应如何受到项目外显学习经验的影响。老年被试和青年被试首先学习一些物体图片, 这些熟悉的图片与一些新图片作为之后工作记忆任务的靶或分心物。结果发现, 老年被试与青年被试在追逐靶和排除分心物的过程中均受到项目之前学习经验的影响。无论是老年被试还是青年被试, 对靶的反应时均快于对分心物的反应时, 对外显学习过的靶(即熟悉靶)的反应时快于对未学习过的靶(即新靶)的反应时, 而拒绝熟悉的分心物需要的时间长于拒绝新分心物的时间。其次, 老年被试与青年被试均表现出对靶的重复效应, 即当靶(无论是熟悉的还是新的)在任务中重复出现时, 对其的反应时加快; 然而, 对分心物的重复效应显著减小。随着项目多次重复, 重复效应整体上减小, 但该效应的变化受到项目属性(靶或分心物)以及项目之前学习经验的影响。重要的是, 当熟悉的分心物反复出现时, 老年被试不但没有出现重复效应, 反而在拒绝该熟悉分心物上表现出困难, 反应时显著延长, 而在青年被试上没有该表现。这些结果说明, 老年被试的工作记忆任务成绩容易受到内隐熟悉性的干扰, 重复出现的干扰项产生的熟悉性使得老年被试难以拒绝。     

语义联系对关联再认神经机制的调节

已有研究显示,关联再认可记录到分别反映双重加工模型的两阶段（即熟悉和回忆）的ERP成分（即FN400和LPC成分）,且具有高语义联系配对的关联再认可通过整合在基于熟悉加工的基础上完成。然而,不同语义联系对关联再认神经机制的影响及单个项目的熟悉和回忆加工的调节作用尚未揭示。为此,本研究比较了主题相关和类别相关图形关联再认的波形波幅异同,并分析了单个项目的熟悉和回忆加工对配对识别的影响。结果显示,主题相关和类别相关条件的旧配对、重组配对和“旧+新”配对均记录到反映熟悉加工的FN400成分,主题相关条件的旧配对、重组配对和“旧+新”配对均记录到反映回忆加工的LPC成分,类别相关条件的旧配对记录到LPC成分。表明关联再认的神经机制受语义联系所调节,单个项目的熟悉程度可影响配对识别时的神经机制,上述结论支持双重加工模型。     

Event-related potential evidence for multiple causes of the revelation effect

Asking people to discover the identity of a recognition test probe immediately before making a recognition judgment increases the probability of an old judgment. To inform theories of this "revelation effect," event-related potentials (ERPs) were recorded for revealed and intact test items across two experiments. In Experiment 1, we used a revelation effect paradigm where half of the test probes were presented as anagrams (i.e., a related task) and the other items were presented intact. The pattern of ERP results from this experiment suggested that revealing an item decreases initial familiarity levels and caused the revealed items to elicit similar levels of activity. In Experiment 2, half of the probes were preceded by an addition task (i.e., an unrelated task). The pattern of ERP effects in this study were distinct from those observed in Experiment 1. More specifically, revealed item ERPs were more negative than intact ERPs at frontal electrodes and more positive at parietal electrodes early in the interval. Later in the epoch, revealed item ERPs were more negative than intact items. These data suggest that related tasks decrease familiarity and alter the signal-to-noise ratio of old and new items, whereas unrelated tasks affect processing in a different way (perhaps by changing decision processes) that also results in the revelation effect. The implications for current theories of the revelation effect are discussed.     

Affective valence and P300 when stimulus arousal level is controlled

Visual stimuli from the International Affective Picture System (IAPS) were employed in a modified oddball paradigm to elicit the P300 event-related brain potential (ERP) in young adult females (N=12). The pictures varied on valence (negative, neutral, positive) ratings but had the same medium arousal level ratings. The images were presented as targets with a standard stimulus composed of red/white triangles designed to mimic the spatial frequency of the pictures. P300 amplitude from negative relative to neutral stimuli was smaller over frontal areas, whereas amplitude from positive relative to neutral stimuli did not differ. P300 amplitude differences among valence categories were consistent across the midline electrodes, and did not change over the parietal area where arousal effects are typically observed. The findings suggest that valence affects P300 frontal amplitude, and arousal level should be controlled when using emotional stimuli to elicit ERPs. Theoretical implications are discussed.     

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。     

Age-related differences in working memory: ERPs reveal age-related delays in selection- and inhibition-related processes

Faulty inhibition is implicated in age-related working memory decline. ERP signs of selection and inhibition of items in working memory (WM) are, respectively, a cue-locked parietal positivity (～350 ms) and a probe-locked frontal negativity (～520 ms). To determine when in the older age range differences in selective and inhibitory processes might occur, ERPs were recorded in a WM task from 20 young (20–28), 20 young–old (60–70), and 20 old–old (71–82) adults. A 4-digit display was followed by a cue indicating which 2 of 4 digits were relevant. Proactive interference (PI), the reaction time difference between a matching and non-matching to-be-ignored digit was larger, relative to the young, in both older groups. Compared to the young, both the cue- and probe-locked activities were prolonged in the older groups. Although there were no topographic differences among the age groups, the prolonged PI and associated ERPs suggest a relative age-related deficit in inhibition.     

Implicit expectations influence target detection in children and adults

When a sound occurs at a predictable time, it gets processed more efficiently. Predictability of the temporal structure of acoustic inflow has been found to influence the P3b of event‐related potentials in young adults, such that highly predictable compared to less predictable input leads to earlier P3b peak latencies. In our study, we wanted to investigate the influence of predictability on target processing indexed by the P3b in children (10–12 years old) and young adults. To do that, we used an oddball paradigm with two conditions of predictability (high and low). In the High‐predictability condition, a high‐pitched target tone occurred most of the time in the fifth position of a five‐tone pattern (after four low‐pitched non‐target sounds), whereas in the Low‐predictability condition, no such rule was implemented. The target tone occurred randomly following 2, 3, 4, 5, or 6 non‐target tones. In both age groups, reaction time to predictable targets was faster than to non‐predictable targets. Remarkably, this effect was largest in children. Consistent with the behavioral responses, the onset latency of the P3b response elicited by targets in both groups was earlier in the predictable than the unpredictable conditions. However, only the children had significantly earlier peak latency responses for predictable targets. Our results demonstrate that target stimulus predictability increases processing speed in children and adults even when predictability was only implicitly derived by the stimulus statistics. Children did have larger effects of predictability, seeming to benefit more from predictability for target detection.     

Recognition memory for emotional faces in amnestic mild cognitive impairment: An event-related potential study

ABSTRACT

This study examined the temporal course of emotional face recognition in amnestic mild cognitive impairment (aMCI). Patients and healthy controls (HC) performed a face recognition task, giving old/new responses to previously studied and novel faces displaying a negative or neutral expression. In aMCI patients, recognition accuracy was preserved for negative faces. Event-related potentials (ERPs) revealed disease-related changes in early perceptual components but not in ERP indices of explicit recognition. Specifically, aMCI patients showed impaired recognition effects for negative faces on the amplitudes of N170 and P2, suggesting deficient memory-related processing of negative faces at the stage of structural encoding and during an early recognition stage at which faces are individuated, respectively. Moreover, while a right-lateralized emotion effect specifically observed for correctly recognized faces on the amplitude of N170 was absent in aMCI, a similar emotion effect for successfully recognized faces on P2 was preserved in the patients, albeit with a different distribution. This suggests that in aMCI facilitated processing of successfully recognized emotional faces starts later in the processing sequence. Nonetheless, an early frontal old/new effect confined to negative faces and a parietal old/new effect unaffected by facial emotion were observed in both groups. This indicates that familiarity and conceptual priming processes may specifically contribute to recognition of negative faces in older adults and that aMCI patients can recruit the same retrieval mechanisms as controls, despite disease-related changes on early perceptual ERP components.     

Brain potentials of recollection and familiarity

It is widely hypothesized that separate recollection and familiarity processes contribute to recognition memory. The present research measured event-related brain potentials (ERPs) from 128 head locations to identify patterns of brain activity related to recollection and familiarity. In two experiments, subjects performed a recognition memory task requiring discrimination between previously studied words, similar words that changed plurality between study and test, and new words (following Hintzman & Curran, 1994). The FN400 ERP component (300-500 msec) varied with the familiarity of words (new > studied = similar). The parietal component (400-800 msec) was associated with the recollection of plurality (studied > similar = new). Differences in the timing and spatial topography of the FN400 and parietal effects support the view that familiarity and recollection arise from distinct neurocognitive processes.     

Enactment supports unitisation of action components and enhances the contribution of familiarity to associative recognition

Memory for actions is usually better following subject-performed tasks (SPT) than verbal tasks (VT). We hypothesised that enactment unitises the components of actions such that familiarity can support associative recognition following SPT. To examine this hypothesis, participants studied verb–object pairs in a SPT or VT condition. During testing, they discriminated between intact, recombined and new items and made Remember/Know judgments; additionally, their EEGs were recorded. Associative recognition was better following SPT than VT. Early frontal event-related potentials (ERPs) were graded according to the item status following SPT, but no such effects were found after VT. Similarly, the late parietal ERPs were graded following SPT, whereas these effects were smaller and did not differ between intact and recombined items following VT. We conclude that enactment unitised the action and object so that familiarity could contribute to associative recognition and that recollection became sensitive to the amount of the matching associative information.     

Understanding age-related reductions in visual working memory capacity: Examining the stages of change detection

Visual working memory (VWM) capacity is reduced in older adults. Research has shown age-related impairments to VWM encoding, but aging is likely to affect multiple stages of VWM. In the present study, we recorded the event-related potentials (ERPs) of younger and older adults during VWM maintenance and retrieval. We measured encoding-stage processing with the P1 component, maintenance-stage processing with the contralateral delay activity (CDA), and retrieval-stage processing by comparing the activity for old and new items (old–new effect). Older adults showed lower behavioral capacity estimates (K) than did younger adults, but surprisingly, their P1 components and CDAs were comparable to those of younger adults. This remarkable dissociation between neural activity and behavior in the older adults indicated that the P1 and CDA did not accurately assess their VWM capacity. However, the neural activity evoked during VWM retrieval yielded results that helped clarify the age-related differences. During retrieval, younger adults showed early old–new effects in frontal and occipital areas and a late central–parietal old–new effect, whereas older adults showed a late right-lateralized parietal old–new effect. The younger adults’ early old–new effects strongly resembled an index of perceptual fluency, suggesting that perceptual implicit memory was activated. The activation of implicit memory could have facilitated the younger adults’ behavior, and the lack of these early effects in older adults may suggest that they have much lower-resolution memory than do younger adults. From these data, we speculated that younger and older adults store the same number of items in VWM, but that younger adults store a higher-resolution representation than do older adults.     

Adults' representations of the Earth: Implications for children's acquisition of scientific concepts

When children are asked to draw the Earth they often produce intriguing pictures in which, for example, people seem to be standing on a flat disc or inside a hollow sphere. These drawings, and children's answers to questions, have been interpreted as indicating that children construct naïve, theory‐like mental models of the Earth (e.g. Vosniadou & Brewer, 1992 ). However, recent studies using different methods have found little or no evidence of these mental models, and report that many young children have some scientific knowledge of the Earth. To examine the reasons for these contrasting findings, adults (N = 350) were given the drawing task previously given to 5‐year‐old children. Fewer than half of the adults' pictures were scientific, and 15% were identical to children's ‘naïve’ drawings. Up to half of the answers to questions (e.g. ‘Where do people live?’) were non‐scientific. Open‐ended questions and follow‐up interviews revealed that non‐scientific responses were given because adults found the apparently simple task confusing and challenging. Since children very probably find it even more difficult, these findings indicate that children's non‐scientific responses, like adults', often result from methodological problems with the task. These results therefore explain the discrepant findings of previous research, and support the studies which indicate that children do not have naïve mental models of the Earth.     

双加工再认提取中的情绪记忆增强效应

根据双加工理论, 再认提取可以划分为两种不同的加工：熟悉性与回想。以往的研究普遍认为情绪对再认提取具有增强效应, 但是情绪对再认记忆中两种不同加工方式(熟悉性与回想)的增强效应的神经机制尚存争议。本研究以ERP作为测量手段, 采用修正的“记得/知道”范式对情绪图片进行再认测验, 旨在探究在学习?测验间隔较长的条件下, 情绪信息如何对熟悉性与回想产生增强效应。在行为结果中, 对于知道判断, 情绪图片的记忆表现显著高于中性图片, 情绪效价间没有差异; 对于记得判断, 负性情绪图片的记忆表现要显著高于正性与中性图片。在ERP数据上, 对于知道判断, 情绪图片的FN400新旧效应有增强作用。对于记得判断, 负性图片的LPC的新旧效应波幅显著高于中性与负性图片; 而正性图片的LPC新旧效应增强作用不显著。以上证据表明：学习?测验间隔较长的情况下, 熟悉性再认提取中, 情绪记忆增强效应主要体现在情绪唤醒对记忆强度的提高, 而不仅仅体现在情绪效价对熟悉判断反应倾向的影响。在回想的再认提取中, 情绪效价的调节占据主导地位, 负性情绪图片有显著的情绪记忆增强效应; 正性情绪图片则不具有增强效应。