Evidence for the contribution of a threshold retrieval process to semantic memory

It is widely held that episodic retrieval can recruit two processes: a threshold context retrieval process (recollection) and a continuous signal strength process (familiarity). Conversely the processes recruited during semantic retrieval are less well specified. We developed a semantic task analogous to single-item episodic recognition to interrogate semantic recognition receiver-operating characteristics (ROCs) for a marker of a threshold retrieval process. We fitted observed ROC points to three signal detection models: two models typically used in episodic recognition (unequal variance and dual-process signal detection models) and a novel dual-process recollect-to-reject (DP-RR) signal detection model that allows a threshold recollection process to aid both target identification and lure rejection. Given the nature of most semantic questions, we anticipated the DP-RR model would best fit the semantic task data. Experiment 1 (506 participants) provided evidence for a threshold retrieval process in semantic memory, with overall best fits to the DP-RR model. Experiment 2 (316 participants) found within-subjects estimates of episodic and semantic threshold retrieval to be uncorrelated. Our findings add weight to the proposal that semantic and episodic memory are served by similar dual-process retrieval systems, though the relationship between the two threshold processes needs to be more fully elucidated.     

Encoding modality can affect memory accuracy via retrieval orientation

Research indicates that false memory is lower following visual than auditory study, potentially because visual information is more distinctive. In the present study we tested the extent to which retrieval orientation can cause a modality effect on memory accuracy. Participants studied unrelated words in different modalities, followed by criterial recollection tests that selectively oriented retrieval toward one study modality at a time. Memory errors were lower when oriented toward visual than toward auditory information, thereby generalizing the modality effect to an explicit source memory task. Moreover, these effects persisted independent of the test presentation modality, indicating that retrieval orientation overrode the potential cuing properties of the test stimulus. An independent manipulation check confirmed that visual recollections were subjectively experienced as more distinctive than auditory recollections. These results suggest that retrieval orientation is sufficient to cause a modality effect on memory accuracy by focusing monitoring processes on the recollection of studied features that are diagnostic of prior presentation.     

Recognition memory ROCs for item and associative information: The contribution of recollection and familiarity

Receiver-operating characteristics (ROCs) were examined in three recognition memory experiments. ROCs for item information (i.e., was this word presented?) were found to be curvilinear. However, ROCs for associative information (i.e., were these two words presented together?) were found to be linear. The results are in agreement with the predictions of a dual-process model that assumes that recognition judgments are -based on familiarity and recollection. Familiarity reflects the assessment of a continuous strength dimension and is well described as a signal detection process, whereas recollection reflects the retrieval of qualitative information about the study episode and behaves like a discrete threshold process. The results showed that memory judgments about items relied on a combination of recollection and familiarity, but that judgments about associations relied primarily on recollection. Further examination of the associative ROCs suggested that subjects were able to recollect that old pairs of items were in the study list, and, under some conditions, that new pairs were not in the study list.     

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。     

语义相似性下回忆和熟悉性的分离

该研究利用事件相关电位技术（ERPs）,采用以汉字为实验材料的学习-再认范式,考察了语义相似性下回忆和熟悉性的分离。本实验结果表明：熟悉性效应主要体现在330-430ms的额区,而回忆效应主要体现在430-600ms的中央区和顶区。本实验在以汉字为实验材料的情况下证明了,早期额区的N400新旧效应反映了熟悉性,晚期顶区LPC新旧效应反映了回忆,从汉语材料的角度,为双加工过程假说提供了新的证据。     

Examining the basis for illusory recollection: The role of remember/know instructions

Curiously, studies using the remember/know paradigm to measure recollective experience show that people often vividly remember events that never occurred, a phenomenon referred to asillusory recollection. Two experiments tested the hypothesis that false remember responses in the converging associates, or Deese/Roediger-McDermott (DRM) paradigm, reflect accurate memory for the study episode, rather than false recollection of critical lures. To test this hypothesis, we used standard remember instructions that emphasized recollection of the study context by allowing participants to use memory of surrounding list items as evidence for recollection, or we used modified instructions that did not include memory for surrounding list items as a basis for recollection. Results showed that, as compared with the standard instruction condition, the modified instructions selectively reduced reports of false remember responses to critical lures, but did not affect remember responses to studied items. By contrast, remember responses to critical lures were unaffected by an instruction condition that excluded the use of voice information as evidence for remembering. These results suggest that remember responses to falsely recognized items are driven partly by retrieval of studied items, rather than illusory recollection of the critical lures themselves. They further point to the importance of instructions in influencing subjective reports.     

Aging, spaced retrieval, and inflexible memory performance

Spaced retrieval is a memory-training technique whereby information is tested at progressively longer delays. Two experiments were conducted in order to examine the effects of spaced retrieval on controlled recollection and automatic influences of memory. In Experiment 1, word pairs were read once, three times, or once and retrieved twice by young and older adults. Retrieval practice improved performance on a later test for both age groups. Experiment 2 was arranged so that recollection opposed automatic influences of retrieval practice. Retrieval practice increased intrusions on a later test only for older adults. Results suggest that because of a deficit in recollection, older adults were less able to oppose the automatic influence of spaced retrieval and thus exhibited less flexible memory performance.     

Support for a continuous (single-process) model of recognition memory and source memory

Does memory retrieval occur in a continuous or an all-or-none manner? The shape of the receiver operating characteristic (ROC) has been used to answer this question, with curvilinear and linear memory ROCs indicating continuous and all-or-none retrieval processes, respectively. Signal detection models (e.g., the unequal variance model) correspond to a continuous retrieval process, whereas threshold models (including the multinomial model and the recollection component of the dual-process model) correspond to an all-or-none process. In studies of source memory, Slotnick et al. (2000) and others have observed curvilinear ROCs (supporting the unequal variance model), whereas Yonelinas (1999) observed linear ROCs (supporting the dual-process model). We resolve these seemingly inconsistent results, showing that source memory ROCs are naturally curvilinear but can appear linear when nondiagnostic source information is included in the analysis. Furthermore, the unequal variance model accounted for both recognition memory and source memory ROCs, supporting a continuous process of memory retrieval.     

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.     

Recollection is a continuous process: Evidence from plurality memory receiver operating characteristics

Is recollection a continuous/graded process or a threshold/all-or-none process? Receiver operating characteristic (ROC) analysis can answer this question as the continuous model and the threshold model predict curved and linear recollection ROCs, respectively. As memory for plurality, an item's previous singular or plural form, is assumed to rely on recollection, the nature of recollection can be investigated by evaluating plurality memory ROCs. The present study consisted of four experiments. During encoding, words (singular or plural) or objects (single/singular or duplicate/plural) were presented. During retrieval, old items with the same plurality or different plurality were presented. For each item, participants made a confidence rating ranging from “very sure old”, which was correct for same plurality items, to “very sure new”, which was correct for different plurality items. Each plurality memory ROC was the proportion of same versus different plurality items classified as “old” (i.e., hits versus false alarms). Chi-squared analysis revealed that all of the plurality memory ROCs were adequately fit by the continuous unequal variance model, whereas none of the ROCs were adequately fit by the two-high threshold model. These plurality memory ROC results indicate recollection is a continuous process, which complements previous source memory and associative memory ROC findings.     

一体化促进联结记忆的作用机制：熟悉性和回想加工

当两个或两个以上项目进行一体化编码时, 熟悉性也能够支持联结再认, 这一观点已经得到大量研究证据的支持。然而, 关于一体化如何影响联结再认和构成联结的单个项目再认仍存在分歧。通过回顾现有研究发现：(1)一体化一致性是调节一体化与联结再认关系的重要因素; (2)认知资源有限和新/旧词语义相关性是影响一体化对项目再认作用的重要因素; (3)一体化的发生机制存在“项目假说”、“图式假说”以及“精细加工假说”三种可能的理论解释。未来研究不仅需要控制一体化一致性, 还可以比较不同一体化方式的作用大小以及探索一体化效应的毕生发展规律。     

FN400和LPC对熟悉性和回想的特异性指向分析

双加工理论认为熟悉性和回想是情景记忆的两个独立过程,其重要证据是ERP研究中FN400和LPC可以分别指示熟悉性和回想。但也有研究证明FN400是概念启动和熟悉性共同作用的结果,而LPC也不能准确的反映回想加工,因此,将其作为双加工理论证据的可靠性需进一步讨论。未来需进一步明确概念启动和熟悉性影响FN400的前提条件,并在提高生态效度和控制额外变量的同时明晰LPC的指向性,同时探究熟悉性和回想在再认过程中的具体作用方式。     

The episodic nature of episodic-like memories

Studying episodic memory in nonhuman animals has proved difficult because definitions in humans require conscious recollection. Here, we assessed humans' experience of episodic-like recognition memory tasks that have been used with animals. It was found that tasks using contextual information to discriminate events could only be accurately performed using recollection, not familiarity. However, tasks using temporal information to discriminate events could be accurately performed using either recollection or familiarity. The results strengthen the position that some episodic-like recognition memory tasks are a valid model of episodic memory. However, tasks that rely on temporal information may be susceptible to nonepisodic strategies.     

Identifying the Basis for the Word Frequency Effect in Recognition Memory

Abstract

Recent theories of recognition memory have identified two bases on which recognition-memory judgments may be made: recollection, which involves retrieval of contextual information from an earlier episode of stimulus presentation; and familiarity, which is distinguished by a general sense of familiarity in the absence of recollection. Four experiments were conducted to test whether the word frequency effect (WFE) in recognition memory (superior performance with low- in comparison with high-frequency targets) results from recollection-based processes, familiarity-based processes, or both. In two of the experiments, superior memory for aspects of the study context was found for low-frequency in comparison with high-frequency words, suggesting frequency-related differences in recollection. The other two experiments used Jacoby's (1991) inclusion/exclusion paradigm to provide estimates of the contribution of recollection and familiarity to recognition. In both experiments the data suggested that the WFE is primarily a recollection-based phenomenon. These findings suggest that the recognition memory WFE for old items results primarily from the effects of word frequency on recollection. The implications of these findings for theories of recognition memory 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。     

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。     

Age-related deficits in associative memory: the influence of impaired strategic retrieval

In 2 experiments, the authors investigated whether impaired strategic retrieval processes contribute to the age-related deficit in associative memory. To do so, they compared older and younger adults on measures of associative memory that place high demands on retrieval processes (associative identification and recall-to-reject) to measures that place low demands on such processes (associative reinstatement and recall-to-accept). Results showed that older adults were severely impaired on associative identification and recall-to-reject measures; relatively intact on recall-to-accept measures, unless recollection was prominent; and intact on associative reinstatement measures. Together, these findings suggest that impairment in strategic retrieval accounts for older adults' deficits in memory for associative information and that this deficit, above and beyond poor binding of items, leads to and amplifies an impairment in overall recollection.     

Episodic recollection in animals: “If it walks like a duck and quacks like a duck…”

In humans, episodic memory is most commonly defined as the subjective experience of recollection, presenting a major challenge to the identification of episodic memory in animals. Here we take the position that episodic memory also has several other distinctive qualities that can be assessed objectively in animals, as well as humans, and the examination of these properties provides insights into underlying mechanisms of episodic memory. We focus on recent evidence accumulated in this laboratory indicating that recognition in rats involves a threshold retrieval process, similar to that observed in human episodic recall. Also, rats can remember the temporal order of unique events, characteristic of the replay of vivid episodic memories in humans. Furthermore, rats combine elements of “when” and “where” events occur, as well as the flow of events within a memory, to distinguish memories that share overlapping features, also characteristic of human episodic memory. Finally, all of these capacities are dependent on the hippocampus, which also plays a critical role in human episodic memory. This combination of findings strongly suggests that animals have the same fundamental information processing functions that underlie episodic recall in humans.     

Distinguishing between the success and precision of recollection

Recollection reflects the retrieval of complex qualitative information about prior events. Recently, Harlow and Donaldson developed a method for separating the probability of recollection success from the precision of the mnemonic information retrieved. In the current study, we ask if these properties are separable on the basis of subjective reports—are participants aware of these two aspects of recollection and can they reliably report on them? Participants studied words paired with a location on a circle outline, and at test recalled the location for a given word as accurately as possible. Additionally, participants provided separate subjective ratings of recollection confidence and recollection precision. The results indicated that participants either recollected the target location with considerable (but variable) precision or retrieved no accurate location information at all. Importantly, recollection confidence reliably predicted whether locations were recollected, while precision ratings instead reflected the precision of the locations retrieved. The results demonstrate the experimental separability of recollection success and precision, and highlight the importance of disentangling these two different aspects of recollection when examining episodic memory.     

How does encoding context affect memory in younger and older adults?

How does encoding context affect memory? Participants studied visually presented words viewed concurrently with a rich (intact face) or weak (scrambled face) image as context and subsequently made "Remember", "Know", or "New" judgements to words presented alone. In Experiment 1a, younger, but not older, adults showed higher recollection accuracy to words from rich- than from weak-context encoding trials. The age-related deficit in recollection occurred, in Experiment 1b, even when encoding and retrieval time was doubled in older adults, suggesting that insufficient processing time cannot account for this age-related deficit. In Experiment 1c, dividing attention in young, during encoding, reduced overall memory, though the recollection boost from rich encoding contexts remained, suggesting that reduced attention resources cannot explain this age-related deficit. Experiment 2 showed that an own-age bias, to face images as context, could not explain the age-related differences either. Results suggest that age deficits in recollection stem from a lack of spontaneous binding, or elaboration, of context to target information during encoding.