THE SIMILARITY OF BRAIN ACTIVITY ASSOCIATED WITH TRUE AND FALSE RECOGNITION MEMORY DEPENDS ON TEST FORMAT

Abstract— Event-related potentials (ERPs) were compared for correct recognitions of previously presented words and false recognitions of associatively related, nonpresented words (lures). When the test items were presented blocked by test type (old, new, lure), waveforms for old and lure items were different, especially at frontal and left parietal electrode sites, consistent with previous positron emission tomography (PET) data (Schacter, Reiman, et. al., 1996). When the test format randomly intermixed the types of items, waveforms for old and lure items were more similar. We suggest that test format affects the type of processing subjects engage in, consistent with expectations from the source-monitoring framework (Johnson, Hashtroudi, & Lindsay, 1993). These results also indicate that brain activity as assessed by neuroimaging designs requiring blocked presentation of trials (e g, PET) do not necessarily reflect the brain activity that occurs in cognitive-behavioral paradigms, in which types of test trials are typically intermixed.     

Emotional valence influences the neural correlates associated with remembering and knowing

In the present study, we examined whether emotional valence modulates the neural processes that are engaged during the encoding of information that is later vividly remembered versus that which is only known to be familiar. Participants underwent an fMRI scan while viewing positive, negative, and neutral stimuli. Later, recognized items were labeled as either remembered or known. Negative items that were later vividly remembered recruited temporo-occipital regions associated with sensory processing more than did positive or neutral items that were vividly remembered. The encoding of positive information later known recruited the cingulate gyrus and bilateral frontal and parietal areas—regions associated with episodic and semantic retrieval and self-referential processing—more than did the encoding of negative or neutral items that were later known. These results suggest that memories for negative items may be vividly recollected due to increased sensory processing during encoding, whereas enhanced gist-based processing of positive information may lead to increased feelings of familiarity.     

Reduced effects of pictorial distinctiveness on false memory following dynamic visual noise

High levels of false recognition for non-presented items typically occur following exposure to lists of associated words. These false recognition effects can be reduced by making the studied items more distinctive by the presentation of pictures during encoding. One explanation of this is that during recognition, participants expect or attempt to retrieve distinctive pictorial information in order to evaluate the study status of the test item. If this involves the retrieval and use of visual imagery, then interfering with imagery processing should reduce the effectiveness of pictorial information in false memory reduction. In the current experiment, visual-imagery processing was disrupted at retrieval by the use of dynamic visual noise (DVN). It was found that effects of DVN dissociated true from false memory. Memory for studied words was not influenced by the presence of an interfering noise field. However, false memory was increased and the effects of picture-induced distinctiveness was eliminated. DVN also increased false recollection and remember responses to unstudied items.     

Memory encoding of stimulus features in human perceptual learning

Two experiments analysed memory encoding in human perceptual learning. Both experiments started with preexposure without feedback to four checkerboards composed by a unique feature each and sharing a common feature (AX, BX, CX, and DX). Elements of one pair were presented intermixed and elements of the other pair were presented in separate blocks. Immediately after preexposure participants completed a memory recognition task in which the characteristics of the distractors were manipulated. Experiment 1 showed that only intermixed presentation results in good encoding of the unique features of the stimuli. Experiment 2 demonstrated that intermixed preexposure results in different encoding of unique versus common features of the stimuli: Participants are able to remember A and B better than they remember X, whereas for the blocked condition memory for C, D, and X does not differ. Overall, the results presented here support the proposal that intermixing stimuli results in differential memory traces for unique versus common features and that this contributes to the intermixed/blocked effect.     

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.     

Episodic encoding and recognition of pictures and words: role of the human medial temporal lobes

In the present PET study, we examined brain activity related to processing of pictures and printed words in episodic memory. Our goal was to determine how the perceptual format of objects (verbal versus pictorial) is reflected in the neural organization of episodic memory for common objects. We investigated this issue in relation to encoding and recognition with a particular focus on medial temporal-lobe (MTL) structures. At encoding, participants saw pictures of objects or their written names and were asked to make semantic judgments. At recognition, participants made yes-no recognition judgments in four different conditions. In two conditions, target items were pictures of objects; these objects had originally been encoded either in picture or in word format. In two other conditions, target items were words; they also denoted objects originally encoded either as pictures or as words. Our data show that right MTL structures are differentially involved in picture processing during encoding and recognition. A posterior MTL region showed higher activation in response to the presentation of pictures than of words across all conditions. During encoding, this region may be involved in setting up a representation of the perceptual information that comprises the picture. At recognition, it may play a role in guiding retrieval processes based on the perceptual input, i.e. the retrieval cue. Another more anterior right MTL region was found to be differentially involved in recognition of objects that had been encoded as pictures, irrespective of whether the retrieval cue provided was pictorial or verbal in nature; this region may be involved in accessing stored pictorial representations. Our results suggest that left MTL structures contribute to picture processing only during encoding. Some regions in the left MTL showed an involvement in semantic encoding that was picture specific; others showed a task-specific involvement across pictures and words. Together, our results provide evidence that the involvement of some but not all MTL regions in episodic encoding and recognition is format specific.     

The role of exemplar typicality and encoding strategies in category retrieval-induced forgetting

Selective retrieval practice of category exemplars often impairs the recall of related items, a phenomenon known as retrieval-induced forgetting (RIF). In Experiment 1 the role of item typicality (high, low) and presentation format of category exemplars (random, grouped) were analysed, while in Experiment 2 two encoding strategies (inter and intracategory) to modulate RIF were tested. Exemplar typicality was the critical factor underlying RIF. Competition during retrieval practice rendered RIF in the typical exemplars, but RIF did not appear when the exemplars were low typicality. The greater impairment of strong exemplars is in line with the inhibitory account of RIF and the notion of interference dependence. Inhibition appeared with random and grouped presentations suggesting that presentation format of the exemplars is not a critical factor in modulating RIF in a category-cued recall task. Distinctive processing instructions using sentences that connected items from different categories (intercategory strategy) and integration instructions by using size to organise the exemplars within categories (intracategory strategy) easily avoided competition and the need of inhibition processes in recall.     

Two bs or not two Bs? A signal detection theory analysis of repetition blindness in a counting task

Stimulus repetition usually benefits performance. A notable exception is repetition blindness (RB), in which subjects fail to report a repeated stimulus in a rapid serial visual presentation. Theories differ in attributing RB to either perceptual encoding or memory retrieval and to impaired discrimination versus response bias. In the present study, subjects judged whether one or two letters were imbedded in sequences of digits. Unlike previous studies, false guesses of two unrepeated letters were distinguished from false guesses of two repeated letters. When repeated- and unrepeated-letter trials were randomly intermixed (Experiment 1), RB was entirely attributable to response bias. However, when they were separately blocked (Experiments 2 and 3), RB was manifested in discriminability (d'). The results support perceptual-encoding accounts of RB but indicate that effects on discriminability depend on subjects' processing strategies.     

合体字与复合词中联结编码和项目编码的关系

本研究通过考察合体字和复合词加工过程中联结记忆和项目记忆的变化,探究了在将不同项目绑定为整体的过程中联结编码和项目编码间的关系,并结合脑电技术比较了合体字和复合词的加工过程在神经机制上的差异。行为结果显示:与不能组成字或词的编码条件相比,合体字和复合词编码条件下的联结记忆成绩有显著提升,且项目记忆成绩没有下降;与复合词编码相比,合体字编码条件下的联结记忆和项目记忆成绩都显著更好。脑电结果显示:复合词编码时晚期负成分(LNC)主要位于额区且发生较早,而合体字编码时的LNC主要位于枕区且发生更晚;合体字编码比复合词编码在α/β频段的神经振荡去同步化更强。这些结果表明,将不同项目绑定为整体的操作可以强化大脑对联结信息的加工,同时不会损害对项目的加工,支持了“只有收益”的观点。本研究也从实证的角度为汉语学习材料的编排提供了参考。     

The role of attention in remembering important item-location associations

When encountering an excess of information, people are able to selectively remember high-value information by strategically allocating attention during the encoding period, termed value-directed remembering. This has been demonstrated in both the episodic verbal and visuospatial memory domains. Importantly, the allocation of attention also plays a crucial role in the binding of identity and location information in visuospatial memory. We examined how taxing attentional resources to various degrees during encoding might affect visuospatial memory and selectivity. Participants studied items paired with point values indicating their value in a grid display and were asked to maximize their point score (a summation of the points associated with correctly remembered information). Participants viewed items under either a sequential or simultaneous presentation format and in either the presence or absence of a secondary tone discrimination task. While participants in the divided attention conditions recalled fewer item-location associations overall, participants in all encoding conditions prioritized high-value information in memory, providing further evidence that selectivity can be maintained even when attentional resources are taxed. However, differences between presentation formats emerged when conducting spatial resolution analyses examining errors. Errors in the simultaneous conditions were only influenced by item value when attention was full during encoding, while errors in the sequential conditions were not influenced by item value, regardless of available attentional resources. The results suggest participants can strategically allocate attention during encoding even under cognitively-demanding conditions and that gist-based visuospatial memory may only be influenced by information importance when adequate attentional resources are available.     

跨视听通道的相继错误记忆效应

本研究以12名大学生为被试采用DRM范式,考察了视觉与听觉通道在编码阶段的错误记忆ERP效应,以从更深层面认识错误记忆的内在加工机制。研究结果表明,在编码阶段,在300-500ms及500-700ms的时间窗视觉通道均存在相继错误记忆效应（DIM）,比听觉通道表现出较强的DIM效应,这不仅说明视觉通道与听觉通道在编码阶段具有不同的脑机制,而且表明DIM效应与学习项目的语义加工有着密切的关系。     

The neural regions sustaining episodic encoding and recognition of objects

In this functional MRI experiment, encoding of objects was associated with activation in left ventrolateral prefrontal/insular and right dorsolateral prefrontal and fusiform regions as well as in the left putamen. By contrast, correct recognition of previously learned objects (R judgments) produced activation in left superior frontal, bilateral inferior frontal, and right cerebellar regions, whereas correct rejection of distractor objects (N judgments) was associated with activation in bilateral prefrontal and anterior cingulate cortices, in right parietal and cerebellar regions, in the left putamen, and in the right caudate nucleus. The R minus N comparison showed activation in the left lateral prefrontal cortex and in bilateral cingulate cortices and precunei, while the N minus R comparison did not reveal any positive signal change. These results support the view that similar regions of the frontal lobe are involved in episodic encoding and retrieval processes, and that the successful episodic retrieval of newly learned objects is mainly based on a frontoparietal network.     

有意遗忘的脑机制

有意遗忘是指个体主动忘记无用和过时的信息,本质是记忆的主动抑制,包括定向遗忘和压抑遗忘。在定向遗忘中,记忆抑制既发生在编码阶段也发生在提取阶段,脑机制研究支持编码抑制理论和提取抑制理论;在压抑遗忘中,think和No-think所激活的脑区不同,No-think引起前额区域的激活增强和海马的激活减弱。未来应开展定向遗忘和压抑遗忘的脑机制差异研究,注重记忆抑制和其他心理活动抑制之间的差异研究,关注创伤个体的有意遗忘研究,拓展记忆控制神经网络的可塑性研究。     

In Search of the Self: A Positron Emission Tomography Study

Abstract—Previous work using positron emission tomography (PET) has shown that memory encoding processes are associated with preferential activation of left frontal regions of the brain, whereas retrieval processes are associated predominantly with right frontal activations. One possible reason for the asymmetry is that episodic retrieval necessarily involves reference to the self, and the self-concept may be represented (at least partially) in right frontal regions. Accordingly, the present study investigated the possibility that encoding of self-related material might also activate right frontal areas. Eight right-handed volunteers judged trait adjectives under four separate PET scan conditions: (a) relevance to self, (b) relevance to a well-known public figure, (c) social desirability, and (d) number of syllables. The results showed that self-related encoding yielded left frontal activations similar to those associated with other types of semantic encoding, but also specific activations in the right frontal lobe. It is concluded that the concept of self involves both general schematic structures and further specific components involved in episodic memory retrieval.     

Cognitive psychometrics: assessing storage and retrieval deficits in special populations with multinomial processing tree models

This article demonstrates how multinomial processing tree models can be used as assessment tools to measure cognitive deficits in clinical populations. This is illustrated with a model developed by W. H. Batchelder and D. M. Riefer (1980) that separately measures storage and retrieval processes in memory. The validity of the model is tested in 2 experiments, which show that presentation rate affects the storage of items (Experiment 1) and part-list cuing hurts item retrieval (Experiment 2). Experiments 3 and 4 examine 2 clinical populations: schizophrenics and alcoholics with organic brain damage. The model reveals that each group exhibits deficits in storage and retrieval, with the retrieval deficits being stronger and occurring more consistently over trials. Also, the alcoholics with organic brain damage show no improvement in retrieval over trials, although their storage improves at the same rate as a control group.     

Variation in working memory capacity and episodic recall: The contributions of strategic encoding and contextual retrieval

The present study examined the extent to which differences in strategic encoding and contextual retrieval account for the relation between individual differences in working memory capacity (WMC) and variation in episodic recall. Participants performed a continual distractor task under either incidental- or intentional-encoding conditions. High-WMC individuals outperformed low-WMC individuals across both encoding conditions and, notably, to a greater degree in the intentional-encoding condition. These results suggest that WMC differences in episodic recall are likely due to a combination of differences in both contextual-retrieval and strategic-encoding processes. These findings are consistent with prior work showing that high-WMC individuals are better at engaging in strategic-encoding processes during the presentation of items than are low-WMC individuals and are better at using contextual cues to focus the search on correct items during retrieval.     

编码与提取方式对生成效应的影响

实验采用两种编码方式和测验类型考查了编码与提取方式的一致性对生成效应的影响。结果显示：(1)在进行字形加工的知觉辨认测验中,生成过程主要依据字形编码的形近字出现了生成效应;主要依据字义编码的反义字没有出现此效应。(2)在依赖字义提取的自由回忆中,形近字和反义字都出现了生成效应。因而编码与提取方式的一致性可能对生成效应有影响。     

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.     

编码如何预测提取?以相继记忆效应为证

在记忆领域, 编码与提取之间的关系始终备受关注。近37年(1980至今)的研究显示, 随后记住信息与随后遗忘信息在编码阶段关联的神经机制明显不同(该差异被称为相继记忆效应), 表明编码能够从神经机制角度预测提取。过去10年间(2008~2017), 研究者在顺承先前研究的基础上另辟蹊径, 重点从编码任务中加工水平及目标导向对相继记忆效应的影响、提取任务对相继记忆效应的影响、不同年龄群体之间的相继记忆效应异同、情绪项目和情绪背景对相继记忆效应的影响等角度展开研究。本文从上述四方面对相关研究进行了详细梳理, 并从整合研究成果、完善理论模型、挖掘潜在社会因素、探究个体差异和群体差异以及加强应用推广等方面对今后研究进行展望。     

编码与提取干扰对内隐和外显记忆的非对称性影响

以往研究表明在外显记忆中,编码与提取加工存在着非对称性,但在内隐记忆中,二者的关系并不明确,因此实验采用“学习-再认”范式,考察在编码或提取中分别附加的干扰任务对词汇判断或再认产生的影响。结果证实编码与提取干扰对内隐或外显记忆都具有非对称性的影响,但又存在着差异,即编码干扰会导致随后外显记忆成绩显著减少,而提取干扰对其影响较小,相反,编码干扰对随后内隐测验中启动效应的影响较小,但提取干扰会破坏启动效应,从而为内隐记忆和外显记忆的分离提供了进一步的证据