Memory and consciousness: trace distinctiveness in memory retrievals

The aim of this article was to provide experimental evidence that classical dissociation between levels of consciousness associated with memory retrieval (i.e., implicit or explicit) can be explained in terms of task dependency and distinctiveness of traces. In our study phase, we manipulated the level of isolation (partial vs. global) of the memory trace by means of an isolation paradigm (isolated words among non-isolated words). We then tested these two types of isolation in a series of tasks of increasing complexity: a lexical decision task, a recognition task, and a free recall task. The main result of this study was that distinctiveness effects were observed as a function of the type of isolation (level of isolation) and the nature of the task. We concluded that trace distinctiveness improves subsequent access to the trace, while the level of trace distinctiveness also appears to determine the possibility of conscious or explicit retrieval.     

What causes the isolation effect?

Events that are incongruent with their prevailing context are usually very well remembered. This fact often is described as the distinctiveness effect in memory, an effect that has served as explanation not only of memory phenomena but also of various other phenomena, including social judgment. The core laboratory paradigm for studying distinctiveness in memory research has long been the isolation paradigm. This paradigm, sometimes attributed to H. von Restorff, yields better memory for an item categorically isolated from surrounding items than for the surrounding items and a proper control item. The authors offer an interpretation of the isolation effect based on the analysis of the processing of similarities and differences among the items. Two experiments provide evidence for this interpretation. The results are discussed in the context of current theories of distinctiveness effects in memory. An appeal is made for a different conceptualization of distinctiveness effects, one that treats distinctiveness as a discriminative process in memory that requires processing of both similarities and differences among items.     

Evidence for time-based models of free recall

Is memory temporally organized? According to temporal distinctiveness models of memory, temporally isolated items should be better remembered than temporally crowded items in free recall tasks. Here, we tested this class of model by varying the temporal isolation of items either predictably (Experiment 1) or unpredictably (Experiment 2) in a free recall task. In both experiments, item recall probability increased as a function of the temporal gaps both before and after the item. The results are taken as support for temporal distinctiveness models of memory, in which items are represented and recalled in terms of their positions along a temporal dimension.     

Temporal isolation effects in recognition and serial recall

Recent temporal distinctiveness models of memory predict that temporally isolated items will be recalled better than temporally crowded items. The effect has been found in some tasks (free recall, memory for serial order when report order is unconstrained, running memory span) but not in others (forward serial recall). Such results suggest that the attentional weighting given to a temporal dimension in memory may vary with task demands. Here, we find robust temporal isolation effects in recognition memory (Experiment 1) and a smaller isolation effect in forward serial recall when an open pool of items is used (Experiment 2). Analysis of 26 temporal isolation effects suggests that the phenomenon occurs in a range of tasks but is larger when it is useful to attend to a temporal dimension in memory. The overall pattern of results is taken to favor memory models that rely on multiple weighted dimensions in memory, one of which is temporal.     

提取干扰对不同类型内隐记忆的影响

以往研究关于提取阶段的干扰是否会影响内隐记忆存在着异义, 其中一个重要因素可能源于所采用的内隐记忆测验类型的差异。本研究采用学习-测验范式, 通过4个实验, 分别考察了提取干扰对识别式知觉内隐测验、识别式概念内隐测验、产生式知觉内隐测验和产生式概念内隐测验的影响, 以期对提取干扰和内隐记忆之间的关系有着更全面的了解。结果表明: (1)词汇判断任务(识别式知觉)和语义分类任务(识别式概念)的启动效应在提取干扰下消失了, (2)而产生式词汇判断任务(产生式知觉)和产生式语义分类任务(产生式概念)在提取干扰下仍发现了明显的启动效应, 但与无干扰条件相比, 启动效应量也有着明显的减少。由此可见, 不同类型的内隐记忆都会受到提取干扰的影响, 相比于产生式启动, 识别式启动更容易受到提取干扰的破坏。     

Spatial distinctiveness effect in categorisation

The aim of the present study was to show that the probability of an item being retrieved is proportional to its spatial distinctiveness, and that this distinctiveness effect can be obtained in an implicit memory task. The participants were presented with two phases in which they had to categorise pictures of objects as either “kitchen utensils” or “do-it-yourself tools”. In our encoding phase, the pictures were successively presented in different positions on the screen. The positions were arranged in one of two different configurations: a “distinctive condition” in which the pictures were placed in two circles, one central and one peripheral, such that the distance between the pictures was greater when they were in a peripheral position than in a central position, and a “nondistinctive” condition, in which the distance between the pictures was constant irrespective of their central or peripheral position. In the test phase, the same pictures were presented for categorisation, mixed with new pictures at the centre of the screen. The results clearly confirmed our expectations.     

Combining two separate series into a single ordering: Testing the local and global distinctiveness theories with absolute and relative judgments

This study examined the differential effects of an absolute versus a relative judgment task on the retrieval of the border-position items after the combining of two separate serial lists. Under the absolute judgment condition (Experiment 1), the border-position items showed a local distinctiveness effect (faster judgment on these items than on the neighboring items), consistent with the prediction of the local distinctiveness theory of order memory, but not under the relative judgment condition (Experiment 2). The absence of the local distinctiveness effect under the relative judgment condition was consistent with the prediction of the global distinctiveness theory that a midseries item cannot be remembered better than its neighbors. The causes of the differential effects of the two judgment tasks were discussed.     

Distinctiveness and serial position functions in implicit memory

Serial position functions, with their characteristic primacy and recency effects, are ubiquitous in episodic memory tasks, and have also been observed in tasks tapping semantic memory. However, only one experiment, [Raanaas, R. K., & Magnussen, S. (2006a). Serial position effects in implicit memory. European Journal of Cognitive Psychology, 18, 398–414. doi:10.1080/09541440500162065], has demonstrated primacy and recency effects in implicit memory using an indirect memory test. In Experiment 1, we replicate this finding and in Experiment 2, we confirm a prediction that holds only if the serial position function observed in Experiment 1 was a “real” serial position function. These results confirm the presence of serial position functions in implicit memory and also support a general prediction of the relative distinctiveness principle that serial position functions should obtain whenever a set of items are ordered along a relevant dimension.     

The fate of originally presented surface information following recall errors in sentence memory tasks

Pictures are remembered better than their names. This picture superiority effect in episodic memory has been attributed either to the greater sensory distinctiveness of pictures or to their greater conceptual distinctiveness. Weldon and Coyote (1996) tested the conceptual distinctiveness hypothesis by comparing how well pictures as opposed to words primed in two conceptual implicit memory tasks (category production and word association). They found no picture superiority in priming and concluded that the basis of the picture superiority effect must then be pictures' greater sensory distinctiveness. Using the same logic, we compared how well pictures as opposed to words primed in a perceptual implicit memory task (picture and word fragment identification). The sensory distinctiveness theory would predict that pictures should prime picture fragment identification better than words prime word fragment identification, a result we call the picture superiority in within-form priming. Across three experiments which manipulated the encoding task at study, only one showed picture superiority in within-form priming. In contrast, in all three experiments there was robust picture superiority in recall, and exposure to pictures and words at study and test produced independent effects in which both study and test exposure to pictures was more effective for recall than exposure to words. We consider how these results might be reconciled by differences in retrieval demands between recall and fragment identification.     

Recollective performance advantages for implicit memory tasks

A commonly held assumption is that processes underlying explicit and implicit memory are distinct. Recent evidence, however, suggests that they may interact more than previously believed. Using the remember–know procedure the current study examines the relation between recollection, a process thought to be exclusive to explicit memory, and performance on two implicit memory tasks, lexical decision and word stem completion. We found that, for both implicit tasks, words that were recollected were associated with greater priming effects than were words given a subsequent familiarity rating or words that had been studied but were not recognised (misses). Broadly, our results suggest that non-voluntary processes underlying explicit memory also benefit priming, a measure of implicit memory. More specifically, given that this benefit was due to a particular aspect of explicit memory (recollection), these results are consistent with some strength models of memory and with Moscovitch's (2008) proposal that recollection is a two-stage process, one rapid and unconscious and the other more effortful and conscious.     

言语记忆对视觉选择的影响:基于维度的自动注意引导

两个实验分别考察外显和内隐言语记忆中的特征维度信息对基于维度的视觉选择性注意的自动引导作用。实验一要求被试在言语工作记忆(外显言语记忆)保持阶段完成一个视觉注意任务,结果发现了显著的一致性效应,即记忆任务相关维度和注意任务相关维度不一致条件下的注意任务反应时要显著慢于两者一致条件下的反应时;实验二采用go/no-go任务以考察内隐言语记忆对视觉选择的影响,结果也发现了类似的一致性效应。这些结果表明外显和内隐言语记忆中的抽象维度信息自动引导注意选择视场中与之匹配的视觉维度,而不管该维度是否为当前注意任务的相关维度。     

Long-term effects of testing on the recall of nontested materials

The isolation paradigm is a staple in the study of distinctiveness and memory. Isolated items are better remembered than non-isolated controls, and the standard interpretation of this effect is that subjective experience of salience recruits extraordinary processing to the isolated item. This interpretation is at odds with data showing an isolation effect when the isolate is not perceived as salient (e.g., von Restorff, 1933). All available research on the early isolation effect has tested memory after a relatively short retention interval. Perhaps the effect of salience on memory in the isolation paradigm would be revealed following longer retention intervals. The experiment reported here examines the effect of isolation following a 48-hour retention interval when the isolate evokes an experience of salience compared to when the isolate does not evoke that reaction. The isolation effect was substantial after the 48-hour delay but equally so for early and late isolation. Salience appears to have nothing to do with the memory processes even at the longer retention intervals.     

Age-related differences in memory after attending to distinctiveness or similarity during learning

Episodic memory is vulnerable to age-related change, with older adults demonstrating both impairments in retrieving contextual details and susceptibility to interference among similar events. Such impairments may be due in part to an age-related decline in the ability to encode distinct memory representations. Recent research has examined how manipulating stimulus properties to emphasize distinctiveness can reduce age-related deficits in memory. However, few studies have addressed whether learning strategies that differentially encourage distinctiveness processing attenuate age-related differences in episodic memory. In the present study, participants engaged in two incidental encoding tasks emphasizing either distinctiveness or similarity processing. Results demonstrated higher rates of recollection for stimuli studied under the distinctiveness task than the similarity task in younger but not older adults. These findings suggest a declining capacity for distinctiveness processing to benefit memory in older adults, and raise the possibility that strategies that enhance gist-based encoding may attenuate age-related memory deficits.     

Input- and output-monitoring in implicit and explicit memory

Previous experiments have shown that the procedure of questioning subjects retrospectively about the input and output status of information (input and output monitoring) is a useful method for assessing the awareness states of subjects during implicit and explicit memory tasks. The main purpose of the present study was to investigate whether the previous findings could be extended to other implicit and explicit memory tasks. We were especially interested in whether differences in input- and output-monitoring performance can be observed when both the implicit and explicit memory tasks are conceptual ones. In a final test phase, the target items from the study phase and new distractor items were presented. In a recognition-like situation, subjects had to decide whether an item had been presented in the study phase (input status), as well as whether they had produced the item in the memory-test phase (output status). In all three experiments judgments about the input status - but only for those items that had been produced in the implicit or in the explicit memory test - were more precise after explicit than after implicit memory testings. This finding was not influenced by the distinction between perceptual and conceptual-memory tasks (Exp. 1), and was obtained under conditions in which the implicit and the explicit memory tasks were both conceptual and differed only in test instructions (Exps. 2 and 3). These results suggest that not only subjects performing a perceptual test of implicit memory, but also subjects in a conceptual implicit test were less aware of using information from a previous study episode than subjects who received memory instructions. It is concluded that requiring judgments about the input status of information is a good method for assessing subjects test awareness and is preferable to the use of a questionnaire (Exp. 3). In contrast, in all three experiments no differences were found with the output-monitoring measure between implicit and explicit test conditions.     

Providing support for distinctive processing: the isolation effect in young and older adults

The isolation paradigm is the classic method for studying the effects of distinctiveness on memory (Hunt, 1995). Previous studies using the isolation paradigm with older adults (Bireta, Suprenant, & Neath, 2008; Cimbalo & Brink, 1982; Geraci, McDaniel, Manzano, & Roediger (2009); Vitali et al., 2006) placed the isolated items late in the study list. The current experiments, which are the first to investigate the isolation effect in young and older adults when the isolated item occurs early in the list, were motivated by a new framework for understanding age-related differences in the beneficial effects of distinctive processing. The framework, which is motivated by Hunt's (2006) discussion of distinctiveness and Craik's (1986) environmental support view, proposes that when contextual support is provided for the processing of both the difference and similarity components, older adults are more likely to show beneficial effects of distinctiveness. In Experiment 1, young adults showed both early and late isolation effects, while older adults showed only a late isolation effect. In the first experiment the isolated item was the word "table" in a list of fish names. In Experiment 2, the contrast between the isolated item and background items was increased by isolating numbers in a list of words. In the second experiment older adults, as well as young adults, showed an early isolation effect.     

Local temporal distinctiveness does not benefit auditory verbal and spatial serial recall

In the present study, we examined the role of randomly arranged temporal intervals preceding and following items (pre- and postitem intervals, respectively) in auditory verbal and spatial recall tasks. The duration of the pre- and postitem intervals did not affect serial recall performance. This finding calls into question (1) the suggestion that the interval following an item permits the consolidation of information in memory, even in a relatively demanding spatial task, and (2) the prediction that temporal distinctiveness should improve performance. The latter was explored further by showing that in contrast to our empirical data, a relative temporal distinctiveness model produced significant increases in recall performance when pre- and postitem intervals increased. The results are discussed with regard to recent studies revisiting the role of temporal isolation in short-term serial memory.     

The dissociation of repetition priming and recognition memory in language/learning-disabled children.

Recent research has found that the performance of learning-disabled and non-disabled children is dissociated on explicit and implicit tests of memory (Lorsbach & Worman, 1989). The current study further examined this phenomenon by comparing language/learning-disabled (L/LD) and nondisabled children (NLD) on tasks measuring primed picture-naming and item recognition. Included within the design of the experiment was the manipulation of both presentation format (pictures or words) and retention interval (immediate or 1 day). Children were initially presented with pictures and words. Performance was measured both immediately and following a 1-day retention interval on a picture naming task, an item recognition task, and a supplementary measure of memory for presentation format. The magnitude of facilitation associated with primed picture-naming was found to be independent of item recognition performance. In addition, the effects of population (L/LD and NLD) and retention interval (immediate test or 1 day) each produced dissociations between the magnitude of naming facilitation and item recognition performance. Results were discussed in terms of their implications for our understanding of the nature of memory difficulties in L/LD children.     

非熟练中—英双语者跨语言长时重复启动效应

采用跨语言长时重复启动研究范式进一步探讨非熟练中－英双语者的记忆表征模型。被试为华南师范大学大一本科生共140名。实验自变量是语言条件（同语言和跨语言）和学习状况（学习过的和未学习过的）,实验因变量是单词判断的反应时和正确率。实验1中被试在学习和测验阶段都完成概念任务,结果表明获得了跨语言长时重复启动效应。实验2中被试在学习和测验阶段完成词汇任务,结果表明没有获得跨语言长时重复启动效应。实验3中被试在学习阶段完成概念任务,在测验阶段完成词汇任务,结果表明没有获得跨语言长时重复启动效应。实验4中在学习阶段的概念任务中呈现汉语单字词,在测验阶段的词汇任务中呈现英语翻译对等词,结果表明没有获得跨语言长时重复启动效应。总的实验结果表明,在基于内隐记忆的跨语言重复启动的范式下,非熟练中－英双语者的记忆表征支持概念表征共享、词汇表征分离的观点。更重要的是,非熟练中－英双语者需要经由汉语翻译对等词的词汇表征,才能通达英语单词的概念表征,支持了词汇连接模型的观点     

Memory Without Consolidation: Temporal Distinctiveness Explains Retroactive Interference

Is consolidation needed to account for retroactive interference in free recall? Interfering mental activity during the retention interval of a memory task impairs performance, in particular if the interference occurs in temporal proximity to the encoding of the to‐be‐remembered (TBR) information. There are at least two rival theoretical accounts of this temporal gradient of retroactive interference. The cognitive neuroscience literature has suggested neural consolidation is a pivotal factor determining item recall. According to this account, interfering activity interrupts consolidation processes that would otherwise stabilize the memory representations of TBR items post‐encoding. Temporal distinctiveness theory, by contrast, proposes that the retrievability of items depends on their isolation in psychological time. According to this theory, information processed after the encoding of TBR material will reduce the temporal distinctiveness of the TBR information. To test between these accounts, implementations of consolidation were added to the SIMPLE model of memory and learning. We report data from two experiments utilizing a two‐list free recall paradigm. Modeling results imply that SIMPLE was able to model the data and did not benefit from the addition of consolidation. It is concluded that the temporal gradient of retroactive interference cannot be taken as evidence for memory consolidation.