Competition between two memory traces for long-term recognition memory

Previous studies investigating the processes which underlie memory consolidation focused almost exclusively on isolated learning events. Here I studied the competition of two similar memory traces for consolidation non-conditioned recognition memory in adult male C57BL/6JOlaHsd mice using the olfactory cues based social discrimination procedure. My results show that the interference phenomena that cause forgetting are time-dependent, and that retroactive interference can be discriminated from proactive interference. Furthermore, both types of interference can be suppressed by subcutaneous anisomycin treatment immediately after presentation of the interference stimulus. These findings imply that interference phenomena, which result from the competition of two similar memory traces for long-term recognition memory, are related to the progress of memory consolidation and linked to protein synthesis.     

Is scent‐enhanced memory immune to retroactive interference?

Research shows that scent enhances memory for associated information. Current debate centers around scent's immunity to “retroactive interference,” i.e., reduced memory for earlier-learned information after exposure to additional, subsequently-learned information. This paper demonstrates that scent-enhanced memory is indeed prone to retroactive interference, but that some of the information lost is restored using a scent-based retrieval cue. Two process explanations for interference effects are proposed, with the evidence providing more support for an inhibition rather than a response competition explanation. The results enhance our understanding of the encoding and retrieval of olfactory information from long-term memory, and reasons why interference occurs.     

Retrograde Enhancement of Human Kinesthetic Memory by Alcohol: Consolidation or Protection against Interference?

Alcohol intake is known to impair memory in animals and humans. However, five studies reported that “medium” (0.05 ml/kg body weight) to “high” (1.0 ml/kg body weight) doses of alcohol improved memory when drunk immediately after initial learning of verbal or visual material. It was proposed that alcohol brought about this retroactive facilitation either through enhanced consolidation of memory traces or by protecting against retroactive interference. The present double blind study compared the performances of an alcohol and a placebo group on a kinesthetic memory task before alcohol or placebo intake and at retest 1 h after consumption. A second experiment was identical to the first except that all subjects carried out two trials on a T maze in the hour between testing and retesting. The alcohol group in the first experiment performed significantly better than the placebo group at retest (p< .05) but this was not the case in the second experiment. Alcohol therefore enhanced performance on the kinesthetic memory task in the first experiment but may not have protected against the moderate interference from the T maze in the second. The low levels of alcohol could have had a stimulant effect on trace consolidation, perhaps via raised blood glucose levels.     

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。     

Faster forgetting contributes to impaired spatial memory in the PDAPP mouse: Deficit in memory retrieval associated with increased sensitivity to interference?

Two experiments were conducted to investigate the possibility of faster forgetting by PDAPP mice (a well-established model of Alzheimer's disease as reported by Games and colleagues in an earlier paper). Experiment 1, using mice aged 13-16 mo, confirmed the presence of a deficit in a spatial reference memory task in the water maze by hemizygous PDAPP mice relative to littermate controls. However, after overtraining to a criterion of equivalent navigational performance, a series of memory retention tests revealed faster forgetting in the PDAPP group. Very limited retraining was sufficient to reinstate good memory in both groups, indicating that their faster forgetting may be due to retrieval failure rather than trace decay. In Experiment 2, 6-mo-old PDAPP and controls were required to learn each of a series of spatial locations to criterion with their memory assessed 10 min after learning each location. No memory deficit was apparent in the PDAPP mice initially, but a deficit built up through the series of locations suggestive of increased sensitivity to interference. Faster forgetting and increased interference may each reflect a difficulty in accessing memory traces. This interpretation of one aspect of the cognitive deficit in human mutant APP mice has parallels to deficits observed in patients with Alzheimer's disease, further supporting the validity of transgenic models of the disease.     

The dual effect of context on memory of related and unrelated themes: Discrimination at encoding and cue at retrieval

The influence of contextual factors on encoding and retrieval in recognition memory was investigated using a retroactive interference paradigm. Participants were randomly assigned to four context conditions constructed by manipulating types of presentation modality (pictures vs words) for study, interference, and test stages, respectively (ABA, ABB, AAA, & AAB). In Experiment 1 we presented unrelated items in the study and interference stages, while in Experiment 2 each stage contained items from the same semantic category. The results demonstrate a dual role for context in memory processes-at encoding as well as at retrieval. In Experiment 1 there is a hierarchical order between the four context conditions, depending on both target-test and target-interference contextual similarity. Adding a categorical context in Experiment 2 helped to specify each list and therefore better distinguish between target and interferer information, and in some conditions compensated for their perceptual similarity.     

Encoding strategy and retroactive interference in short-term memory

Abstract.— The effect of encoding strategy upon retroactive interference in STM was studied. The subjects were presented two trigrams for retention with the Brown-Peterson method. In half the cases they were to recall both trigrams, in half to recall only the first. The results showed higher recall with the associative than with the rehearsal strategy. An increase in level of retroactive interference was found to increase number of retroactive interference errors in the rehearsal strategy condition and number of omissions in the associative strategy condition. The results were interpreted in terms of the memory trace integration hypothesis.     

Revisiting an old issue: Retroactive interference as a function of the degree of original and interpolated learning

Prior research has generally shown that the greater the degree of original learning of a list, the greater the amount of retroactive interference that list suffers. In addition, greater learning of interpolated lists produces more retroactive interference. However, in prior research, the degree of learning has typically been confounded with the amount of retrieval practice on the list. Two free-recall experiments are reported in which subjects studied one original list and then 0, 1, 2, 3, or 4 interpolated lists. The degree of original and of interpolated learning was manipulated by varying exposure time. In Experiment 1, where the typical confounding of retrieval practice and degree of interpolated learning was present, greater interpolated learning induced greater retroactive interference, which is consistent with prior research. However, in Experiment 2, where the degree of interpolated learning was manipulated without concomitant variation in retrieval practice, retroactive interference was the same, whether the interpolated lists had been learned well or poorly. Therefore, greater interpolated learning does not increase the amount of retroactive interference. The results also show that the amount of retroactive interference does not depend on the degree of original learning, in agreement with other work on normal forgetting.     

Retrieval‐induced forgetting is inversely relatedto everyday cognitive failures

It has recently been suggested ( Anderson, 2003 ) that forgetting is an adaptive process arising from successful inhibition of unwanted items, rather than arising from a failure of the memory system. This inhibition process is thought to make use of retrieval‐induced forgetting (RIF). In the present study, individual susceptibility to RIF was measured in a group of 40 normal participants, whose RIF scores were then compared with their scores on the Cognitive Failures Questionnaire (CFQ). A significant inverse correlation was found between RIF and CFQ scores, indicating that individuals who show a strong RIF effect tend to suffer a lower rate of cognitive failures and forgetfulness in everyday life. These findings are consistent with the hypothesis that RIF might play a role in facilitating memory function by assisting selective retrieval.     

MINERVA 2: A simulation model of human memory

An overview of a simulation model of human memory is presented. The model assumes: (1) that only episodic traces are stored in memory, (2) that repetition produces multiple traces of an item, (3) that a retrieval cue contacts all memory traces simultaneously, (4) that each trace is activated according to its similarity to the retrieval cue, and (5) that all traces respond in parallel, the retrieved information reflecting their summed output. The model has been applied with success to a variety of phenomena found with human subjects in frequency and recognition judgment tasks, the schema-abstraction task, and paired-associate learning. Application of the model to these tasks is briefly summarized.     

Trace loss and the recognition failure of unrecalled words

This paper addresses the phenomenon of recognition failure from the perspective of a theory in which recognition and recall are assumed to involve independent retrieval processes. However, even given independent retrieval, measures of recognition and recall success will covary if any traces are lost from storage, simply because such traces are unavailable for any memory test. In support of the theory, rote learning produced higher covariation between recognition and recall (i.e., fewer recognition failures) than did meaningful elaboration during study. Further, recognition and recall were approximately independent of each other with meaningful elaboration and imagery encoding, regardless of whether the latter involved interactive or separate images. The results of three experiments are discussed in terms of the present “vandal” theory and other theories of recognition failure.     

Absence of adult age differences in forgetting in the Brown-Peterson Task

Despite some recent evidence to the contrary, no reliable age differences in proactive interference (PI) or retroactive interference (RI) were found in a cross-sectional study of adults aged 18-29 and 63-75. Individual memory span was used as the list length in the Brown-Peterson Task in order to achieve stimulus equivalence of memory loads across individuals and age groups. Data from rehearsers were excluded from the analyses in order to isolate age differences in passive forgetting processes from those in rehearsal. PI was manipulated by presenting categorized or uncategorized memory lists. RI was manipulated, holding distractor task difficulty constant, by using words or tones in a signal detection distractor task. It is concluded that age differences are minimal to nonexistent in passive RI-related processes such as decay and perturbation and in passive PI-related processes such as set effects in semantic encoding.     

Trace susceptibility theory

A new theory for the dynamics of trace susceptibility to storage loss is developed and tested. According to the trace susceptibility theory, storage loss occurs when a critical feature for the support of recall is no longer bound to the other features of the trace. The storage loss occurs because of the retroactive influence of other traces, and the storage retention function is precisely characterized by an underlying Weibull distribution. Predictions of the trace susceptibility theory were tested against predictions of a multistore model. The results support the trace susceptibility theory. Finally, the relation between the trace susceptibility theory and proactive interference effects was developed.     

Dissociation of short-term forgetting from the passage of time

In many theories, forgetting is closely linked to the passage of time. In the present experiments, recall in a short-term memory task was less accurate when the retention interval included a difficult arithmetic addition task, compared with an easy task. In a novel condition, the interfering task was switched from hard to easy partway through the retention interval. Recall accuracy at long retention intervals recovered from the level consistent with the hard interfering task to a more accurate level consistent with an easy interfering task. Such recovery is not in agreement with theories that link forgetting to the passage of time, such as trace decay. The reversed forgetting functions are more consistent with an account in which different levels of nonspecific retroactive interference in the retention interval just before the time of retrieval influence different levels of performance accuracy. With the uncoupling of interference levels from time, forgetting is dissociated from the passage of time.     

Coherence and correspondence criteria for rationality: experts' estimation of risks of sexually transmitted infections

The aim of this study is to examine both coherence and correspondence criteria for rationality in experts' judgments of risk. We investigated biases in risk estimation for sexually transmitted infections (STIs) predicted by fuzzy‐trace theory, i.e., that specific errors would occur despite experts' knowledge of correct responses. One hundred twenty professionals with specific knowledge of STI risks in adolescents were administered a survey questionnaire to test predictions concerning: knowledge deficits (producing underestimation of risks); gist‐based representation of risk categories (producing overestimation of condom effectiveness); retrieval failure for risk knowledge (producing lower risk estimates); and processing interference in combining risk estimates (producing biases in post‐test diagnosis of infection). Retrieval was manipulated by asking estimation questions that “unpacked” the STI category into infection types or did not specify infection types. Other questions differentiated processing biases from knowledge deficits or retrieval failure by directly providing requisite knowledge. Experts' knowledge of STI transmission and infection risks was verified empirically. Nevertheless, under predictable conditions, they misestimated risk, overestimated the effectiveness of condoms, and also suffered from processing biases. When questions provided better retrieval supports (unpacked format), risk estimates improved. Biases were linked to gist representations, retrieval failures, and processing errors, as opposed to knowledge about STIs. Results support fuzzy‐trace theory's dual‐process assumptions that different types of errors are dissociated from one another, and separate failures of coherence and correspondence among the same sample of experts. Copyright © 2005 John Wiley & Sons, Ltd.     

Permanence and change in memory: I. Reproduction and recognition of visual figures

Abstract.— A retroactive interference paradigm was employed for studying qualitative memory changes. The name given to an ambiguous visual figure after presentation influenced reproduction and, to a lesser extent, recognition of the figure, indicating that retroactive definition of meaning may lead to memory changes. The relation between the subject's own conception of the meaning of the figure and the name given by the experimenter involved several types of meaning retroaction, which were related to the results on the remembering tasks. The usual interpretation—in line with the permanent-memory hypothesis—attributing changed reproductions either to perceptual change or to interference with the activity of drawing, is not accepted, and a contextual theory of memory is suggested.     

Optimal testing time for suppression of competitors during interference resolution

Interference between competing memory traces is a common cause of memory failure. Recent research has demonstrated a suppression mechanism that operates at retrieval to resolve interference. Using an adaptation of the suppression paradigm in Healey, Ngo, and Hasher [(2014). Below-baseline suppression of competitors during interference resolution by younger but not older adults. Psychological Science, 25(1), 145–151. doi:10.1177/0956797613501169], we tested whether the ability to suppress competing memory traces varies with the synchrony between optimal arousal period and time of testing. We replicate the below-baseline suppression effect for young adults tested at optimal times of day, and present novel evidence that they do not show competitor suppression during non-optimal times of day. In fact, competitors are actually strengthened at non-optimal times. Our results suggest that the ability to resolve interference by suppression varies with circadian arousal.     

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.     

Dissipation of retroactive interference in human infants

In 3 experiments with 85 human 3-month-olds, the authors asked whether retroactive interference with their memory of the original training stimulus is temporary or permanent. Infants learned to move a mobile by kicking and then were exposed to a different mobile (Experiment 1) or context (Experiment 2) immediately or 3 days afterward (Experiment 3). They were tested after increasing delays with the original stimulus, the exposed stimulus, or a completely novel stimulus. Retroactive interference was temporary and unrelated to the exposure delay. The data are consistent with a retrieval-based account of interference. Memory updating (i.e., responding to the interfering stimulus) was coincident with retroactive interference, suggesting that retroactive interference is an adaptive mechanism that facilitates memory updating within a narrow time window.     

Contributions of source and inhibitory mechanisms to age-related retroactive interference in verbal working memory

Determining contributions of source-monitoring and inhibitory function to age-related forgetting has been an elusive goal for cognitive theorists. Five studies used a verbal working memory paradigm to examine mechanisms accounting for disproportionate retroactive interference (RI) experienced with adult aging. Participants distinguished studied target-word pairs from interfering pairs that were read aloud. Source-monitoring and inhibitory task components varied through manipulations of response requirements. RI effects were primarily due to source-monitoring failures rather than to inhibitory failures. Removing both source and inhibitory components eliminated age differences in RI. When source monitoring was emphasized, RI continued to be observed in all age groups but disproportionately for older adults. Process dissociation analyses of memory found recollection decreases and familiarity increases consistent with source failures.