Interference In Short-term Memory Research Articles

Irrelevant changing-state vibrotactile stimuli disrupt verbal serial recall: implications for theories of interference in short-term memory

ABSTRACT What causes interference in short-term memory? We report the novel finding that immediate memory for visually-presented verbal items is sensitive to disruption from task-irrelevant vibrotactile stimuli. Specifically, short-term memory for a visual sequence is disrupted by a concurrently presented sequence of vibrations, but only when the vibrotactile sequence entails change (when the sequence “jumps” between the two hands). The impact on visual-verbal serial recall was similar in magnitude to that for auditory stimuli (Experiment 1). Performance of the missing item task, requiring recall of item-identity rather than item-order, was unaffected by changing-state vibrotactile stimuli (Experiment 2), as with changing-state auditory stimuli. Moreover, the predictability of the changing-state sequence did not modulate the magnitude of the effect, arguing against an attention-capture conceptualisation (Experiment 3). Results support the view that interference in short-term memory is produced by conflict between incompatible, amodal serial-ordering processes (interference-by-process) rather than interference between similar representational codes (interference-by-content).

Phonemic interference in short-term memory contributes to forgetting but is not due to overwriting

Six experiments are reported which examine the pattern of interference created by phonemes being repeated across items in a short-term memory task. Experiments 1 and 2 utilised a serial recall task and demonstrate that when the three phonemes of a target word are distributed across other words in the list, recall of the target word suffers when the distributed phonemes are presented before the target in the list, but not if they occur after the target. Experiment 3 demonstrated that the interference was not a result of rehearsal processes during list presentation, and Experiment 4 replicated the results in a within subject design. Experiments 5 and 6 showed that the interference effect was not due to weaker encoding of the target words when they followed the interfering words by manipulating the order of item recall. It is argued that this phonemic interference occurs at output through a spread of suppression of activation from the recall of earlier list items.

The 'Saw but Forgot' error: A role for short-term memory failures in understanding junction crashes?

Motorcyclists are involved in an exceptionally high number of crashes for the distance they travel, with one of the most common incidents being where another road user pulls out into the path of an oncoming motorcycle frequently resulting in a fatal collision. These instances have previously been interpreted as failures of visual attention, sometimes termed ‘Look but Fail to See’ (LBFTS) crashes, and interventions have focused on improving drivers’ visual scanning and motorcycles’ visibility. Here we show from a series of three experiments in a high-fidelity driving simulator, that when drivers’ visual attention towards and memory for approaching vehicles is experimentally tested, drivers fail to report approaching motorcycles on between 13% and 18% of occasions. This happens even when the driver is pulling out into a safety-critical gap in front of the motorcycle, and often happens despite the driver having directly fixated on the oncoming vehicle. These failures in reporting a critical vehicle were not associated with how long the driver looked at the vehicle for, but were associated with drivers’ subsequent visual search and the time that elapsed between fixating on the oncoming vehicle and pulling out of the junction. Here, we raise the possibility that interference in short-term memory might prevent drivers holding important visual information during these complex manoeuvres. This explanation suggests that some junction crashes on real roads that have been attributed to LBFTS errors may have been misclassified and might instead be the result of ‘Saw but Forgot’ (SBF) errors. We provide a framework for understanding the role of short-term memory in such situations, the Perceive Retain Choose (PRC) model, as well as novel predictions and proposals for practical interventions that may prevent this type of crash in the future.

Serial Dependence across Perception, Attention, and Memory

Information that has been recently perceived or remembered can bias current processing. This has been viewed as both a corrupting (e.g., proactive interference in short-term memory) and stabilizing (e.g., serial dependence in perception) phenomenon. We hypothesize that this bias is a generally adaptive aspect of brain function that leads to occasionally maladaptive outcomes.

Grouping Influences Output Interference in Short-term Memory: A Mixture Modeling Study.

Output interference is a source of forgetting induced by recalling. We investigated how grouping influences output interference in short-term memory. In Experiment 1, the participants were asked to remember four colored items. Those items were grouped by temporal coincidence as well as spatial alignment: two items were presented in the first memory array and two were presented in the second, and the items in both arrays were either vertically or horizontally aligned as well. The participants then performed two recall tasks in sequence by selecting a color presented at a cued location from a color wheel. In the same-group condition, the participants reported both items from the same memory array; however, in the different-group condition, the participants reported one item from each memory array. We analyzed participant responses with a mixture model, which yielded two measures: guess rate and precision of recalled memories. The guess rate in the second recall was higher for the different-group condition than for the same-group condition; however, the memory precisions obtained for both conditions were similarly degraded in the second recall. In Experiment 2, we varied the probability of the same- and different-group conditions with a ratio of 3 to 7. We expected output interference to be higher in the same-group condition than in the different-group condition. This is because items of the other group are more likely to be probed in the second recall phase and, thus, protecting those items during the first recall phase leads to a better performance. Nevertheless, the same pattern of results was robustly reproduced, suggesting grouping shields the grouped items from output interference because of the secured accessibility. We discussed how grouping influences output interference.

Simulating stimulus- and TMS-induced interference in short-term memory using a model of prefrontal cortex

Scalar short-term memory (STM) tasks are those in which the to-be-remembered property of a stimulus can be represented as a scalar quantity – for example, the frequency of a tactile vibration or an auditory pure tone, or the duration or amplitude of a stimulus. Scalar STM tasks have been studied extensively using single-cell methods [1-3], and have proven to be useful model systems for examining behavioural aspects of short-term memory [4-6] and developing computational models [7-10]. In two studies [11,12], we applied a model of prefrontal cortex [9] to experimental datasets [5,13]. In Study 1, we simulated the effects of presenting an irrelevant (distractor) stimulus to experimental subjects during the maintenance period of a vibrotactile scalar STM task by assuming the stimulus was encoded into memory, intruding into the PFC memory store. We were able to replicate previous experimental results [5], and our results also suggested that distractors were only encoded into memory on approximately 50% of trials, consistent with experimental indications that activity in sensory cortex may be inhibited during memory maintenance in order to protect the contents of memory against interference [6,14]. In Study 2, we simulated a previous vibrotactile scalar STM study in which TMS was applied to somatosensory cortex during the maintenance period of the memory task, resulting in decreased performance [13]. We were able to replicate experimental results by assuming that TMS produced increased, noisy neural activity in sensory cortex, which then degraded the contents of the PFC memory store through feedforward interference.

Retroactive interference in short-term memory and the word-length effect

Two experiments investigated the possibility that the word-length effect in short-term memory (STM) is a consequence of long words generating a greater level of retroactive interference than shorter words. In Experiment 1, six-word lists were auditorily presented under articulatory suppression for immediate serial reconstruction of only the first three words. These three words were always drawn from a single set of middle-length words, whereas the last three positions were occupied by either short or long interfering words. The results showed worse memory performance when the to-be-remembered words were followed by long words. In Experiment 2, a recent-probes task was used, in which recent negative probes matched a target word in trial n-2. The results showed lower levels of proactive interference when trial n-1 involved long words instead of short words, suggesting that long words displaced previous STM content to a greater extent. By two different experimental approaches, therefore, this study shows that long words produce more retroactive interference than short words, supporting an interference-based account for the word-length effect.

Neural mechanisms of semantic interference and false recognition in short-term memory

Decades of research using the Deese–Roediger–McDermott (DRM) paradigm have demonstrated that episodic memory is vulnerable to semantic distortion, and neuroimaging investigations of this phenomenon have shown dissociations between the neural mechanisms subserving true and false retrieval from long-term memory. Recently, false short-term memories have also been demonstrated, with false recognition of items related in meaning to memoranda encoded less than 5s earlier. Semantic interference is also evident in short-term memory, such that correct rejection of related lures is slowed relative to correct rejection of unrelated lures. The present research constitutes the first fMRI investigation of false recognition and semantic interference in short-term memory using a short-term DRM paradigm in which participants retained 4 semantic associates over a short 4-s filled retention interval. Results showed increased activation in the left mid-ventrolateral prefrontal cortex (BA45) associated with semantic interference, and significant correlations between these increases and behavioral measures of interference across subjects. Furthermore, increases in dorsolateral PFC occurred when related lures were correctly rejected versus falsely remembered. Compared with false recognition, true recognition was associated with increases in left fusiform gyrus, a finding consistent with the notion that increased perceptual processing may distinguish true from false recognition over both short and long retention intervals. Findings are discussed in relation to current models of interference resolution in short-term memory, and suggest that false short-term recognition occurs as a consequence of the failure of frontally mediated cognitive control processes which adjudicate semantic familiarity in support of accurate mnemonic retrieval.

In search of decay in verbal short-term memory.

Is forgetting in the short term due to decay with the mere passage of time, interference from other memoranda, or both? Past research on short-term memory has revealed some evidence for decay and a plethora of evidence showing that short-term memory is worsened by interference. However, none of these studies has directly contrasted decay and interference in short-term memory in a task that rules out the use of rehearsal processes. In this article the authors present a series of studies using a novel paradigm to address this problem directly, by interrogating the operation of decay and interference in short-term memory without rehearsal confounds. The results of these studies indicate that short-term memories are subject to very small decay effects with the mere passage of time but that interference plays a much larger role in their degradation. The authors discuss the implications of these results for existing models of memory decay and interference.

Interference in short-term memory: the magical number two (or three) in sentence processing.

Many theories have been proposed to explain difficulty with center embedded constructions, most attributing the problem to some kind of limited-capacity short-term memory. However, these theories have developed for the most part independently of more traditional memory research, which has focused on uncovering general principles such as chunking and interference. This article attempts to gain some unification with this research by suggesting that an interesting range of core sentence processing phenomena can be explained as interference effects in a sharply limited syntactic working memory. These include difficult and acceptable embeddings, as well as certain limitations on ambiguity resolution, length effects in garden path structures, and the requirement for locality in syntactic structure. The theory takes the form of an architecture for parsing that can index no more than two constituents under the same syntactic relation. A limitation of two or three items shows up in a variety of other verbal short-term memory tasks as well.

Encoding Processes and Release from Proactive Interference in Short-Term Memory of Preschool Children

Abstract A modified proactive interference paradigm was developed to investigate encoding and memory processes in preschool-age children. The buildup and release from proactive interference in preschool-age children parallels that of adults and of mentally retarded persons, indicating that very young children and older people may use many of the same encoding dimensions.

Amnesic Syndrome: A Lesion-Specific Disorder?

This paper reviews various lines of evidence which suggest that organic amnesia stemming from lesions of the temporal lobe region produce an amnesia that is qualitatively different from that produced by diencephalic lesions. Differences between these two classes of amnesia were found within five dimensions of performance; (a) insight, concern and confabulation, (b) retrograde amnesia, (c) forgetting rate, (d) frontal lobe symptoms, (e) sensitivity to interference in short term memory. The range of differences found suggest that temporal lobe and diencephalic amnesics should not be considered as suffering from the same type of “amnesic syndrome”. It is proposed that future experimental work on amnesia should take full account of neuropathological differences between amnesic patients.

Item similarity and proactive interference in short-term memory

The present paper addresses the question of the nature of interitem similarity effects in short-term retention. An interference theory prediction is pitted against an opposing expectation based on a cognitive strategy subjects could use in the “release-from-PI” paradigm. The experiment consisted of three conditions that differed in the extent of overlap among items in the short-term retention task. Results supported interference theory, in that increasing the interitem similarity of the to-be-recalled items resulted in a substantial decrease in correct recall.

Transfer failure and proactive interference in short-term memory.

Transfer failure and proactive interference in short-term memory.

Transfer failure and proactive interference in short-term memory.

Transfer failure and proactive interference in short-term memory.

Competition processes and proactive interference in short-term memory

A competition model of proactive interference in short-term memory would predict that if subjects are forced to emit low-confidence responses, there will be an increase in both the probability of a correct response and in the number of intrusions. Dillon and Thomas ( Journal of Verbal Learning and Verbal Behavior, 1975 , 14, 603–615) recently performed such an experiment by forcing subjects to guess and found a very modest increase in the probability of a correct response at the cost of a large increase in intrusions. They suggest that these data contradict a competition model. We first argue that their results are not discrepant with the predictions of any realistic competition model and then perform an experiment which tests this same prediction in a slightly different situation. In an experiment using single-word items with conditions arranged so that the probability of a correct response is near one, subjects are run under three different speed-accuracy trade-off conditions: high accuracy, intermediate, and high speed. A competition model would predict that when subjects are forced to respond quickly, there will be an increase in errors, and these errors will tend to be from recent past items. This prediction was confirmed.

Proactive Interference in Short-Term Memory: Recall Probability as a Function of Prior Item Recall

In two different experiments, one with 23 brain surgery patients and one with 39 college students, proactive interference in short-term memory was evaluated as a function of the recall of the just preceding item in a Brown-Peterson distractor technique. In the first experiment, the probability of an error following an error was .25, and the probability of an error following a correct item was .24. In the second experiment, there was also no significant effect ( p > .05) of either prior item repetition or recall upon recall of the subsequent item, except in the case of prior items having a retention interval of 24 sec. In that case, well-remembered items exerted less proactive interference than items on which an error had been made. The results were evaluated in terms of a theory derived from the selector mechanism proposed for long-term memory (Postman, Stark, & Fraser, 1968).

Interference in short-term memory for vocalization: Aural versus visual modality differences.

The Peterson and Peterson short-term memory paradigm involves an interpolated task with several potential dimensions from which interference may orginate: Similarity of items and vocalization. Here we assess the relative interference potency of each on material presented either aurally or visually. Interpolated activity consisting of numbers or words was performed either vocally or silently after either aural or visual presentation of nouns, for which recall was tested after 0, 10, and 30 sec. The magnitude of the vocalization interference effect accounted for 59% and 53% of the total variance at 30 and 10 sec, respectively, whereas the variance associated with similarity was negligible. The effect of similarity emerged dramatically only in the visual presentation condition wherein the silent word task created greater interference than the silent number task. Vocal and silent activity produced differential interference, in partial accord with the dual memory hypothesis.

Interference in short-term memory for vocalization: Aural versus visual modality differences.

Interference in short-term memory for vocalization: Aural versus visual modality differences.

Interpolated task characteristics and interference in short-term memory

The effect of variations in interpolated activity on word recall was examined. Two levels of interpolated task difficulty were factorially combined with three levels of similarity of interpolated items to critical items. The interpolated activities involved either verbal (number or word classification) or nonverbal (tone classification) stimuli. Results indicated that interpolated task difficulty was an important factor influencing word recall at all levels of similarity. In addition, the number and word classification tasks did not differ reliably in their effect on recall, although both resulted in poor recall relative to that following a tone classification task.