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Concept: Interference theory


It is assumed that synaptic strengthening and weakening balance throughout learning to avoid runaway potentiation and memory interference. However, energetic and informational considerations suggest that potentiation should occur primarily during wake, when animals learn, and depression should occur during sleep. We measured 6920 synapses in mouse motor and sensory cortices using three-dimensional electron microscopy. The axon-spine interface (ASI) decreased ~18% after sleep compared with wake. This decrease was proportional to ASI size, which is indicative of scaling. Scaling was selective, sparing synapses that were large and lacked recycling endosomes. Similar scaling occurred for spine head volume, suggesting a distinction between weaker, more plastic synapses (~80%) and stronger, more stable synapses. These results support the hypothesis that a core function of sleep is to renormalize overall synaptic strength increased by wake.

Concepts: Electron, Mass, Learning, Long-term potentiation, Chemical synapse, Similarity, Interference theory


The role of inhibition in the task-switching process has received increased empirical and theoretical attention in the literature on cognitive control. Many accounts have suggested that inhibition occurs when a conflict must be resolved-for example, when a target stimulus contains features of more than one task. In the two experiments reported here, we used variants of backward inhibition, or N - 2 repetition, designs to examine (1) whether inhibition occurs in the absence of conflict at the stimulus or response level, (2) when in the task-switching process such inhibition may occur, and (3) the potential consequences of inhibition. In Experiment 1, we demonstrate that neither stimulus- nor response-level conflict is necessary for inhibition to occur, while the results of Experiment 2 suggest that inhibition may be associated with a reduction of proactive interference (PI) from a previously performed task. Evidence of inhibition and the reduction of PI both occurred at the task-set level. However, inhibition of specific stimulus values can also occur, but this is clearly separable from task-set inhibition. Both experiments also provided evidence that task-set inhibition can be applied at the time of the new task cue, as opposed to at the onset of the target or at the response stage of the trial. Taken together, the results from these experiments provide insight into when and where in the task-switching process inhibition may occur, as well as into the potential functional benefits that inhibition of task sets may provide.

Concepts: Scientific method, Economics, Science, Research, Empiricism, Experiment, Theory, Interference theory


Visuospatial working memory (WM) tasks performed concurrently or after an experimental trauma (traumatic film viewing) have been shown to reduce subsequent intrusive memories (concurrent or retroactive interference, respectively). This effect is thought to arise because, during the time window of memory consolidation, the film memory is labile and vulnerable to interference by the WM task. However, it is not known whether tasks before an experimental trauma (i.e. proactive interference) would also be effective. Therefore, we tested if a visuospatial WM task given before a traumatic film reduced intrusions. Findings are relevant to the development of preventative strategies to reduce intrusive memories of trauma for groups who are routinely exposed to trauma (e.g. emergency services personnel) and for whom tasks prior to trauma exposure might be beneficial.

Concepts: Cognitive psychology, Memory, Memory processes, Episodic memory, Interference theory


In the present study, we examined whether note-taking as a memory aid may provide a naturalistic example of intentional forgetting. In the first experiment, participants played Concentration, a memory card game in which the identity and location of pairs of cards need to be remembered. Before the game started, half of the participants were allowed to study the cards, and the other half made notes that were then unexpectedly taken away. No significant differences emerged between the two groups for remembering identity information, but the study group remembered significantly more location information than did the note-taking group. In a second experiment, we examined whether note-takers would show signs of proactive interference while playing Concentration repeatedly. The results indicated that they did not. The findings suggest that participants adopted an intentional-forgetting strategy when using notes to store certain types of information.

Concepts: Psychology, Concentration, Educational psychology, Memory processes, Playing card, Chess, Game, Interference theory


Despite a substantial amount of animal data linking deficits in memory inhibition to the development of overeating and obesity, few studies have investigated the relevance of memory inhibition to uncontrolled eating in humans. Further, although memory for recent eating has been implicated as an important contributor to satiety and energy intake, the possibility that variations in episodic memory relate to individual differences in food intake control has been largely neglected. To examine these relationships, we recruited ninety-three adult subjects to attend a single lab session where we assessed body composition, dietary intake, memory performance, and eating behaviors (Three Factor Eating Questionnaire). Episodic recall and memory inhibition were assessed using a well-established measure of memory interference (Retrieval Practice Paradigm). Hierarchical regression analyses indicated that memory inhibition was largely unrelated to participants' eating behaviors; however, episodic recall was reliably predicted by restrained vs. uncontrolled eating: recall was positively associated with strategic dieting (β = 2.45, p = 0.02), avoidance of fatty foods (β = 3.41, p = 0.004), and cognitive restraint (β = 1.55, p = 0.04). In contrast, recall was negatively associated with uncontrolled eating (β = -1.15, p = 0.03) and emotional eating (β = -2.46, p = 0.04). These findings suggest that episodic memory processing is related to uncontrolled eating in humans. The possibility that deficits in episodic memory may contribute to uncontrolled eating by disrupting memory for recent eating is discussed.

Concepts: Nutrition, Obesity, Food, Memory, Dieting, Episodic memory, Interference theory


Memory performance exhibits a high level of variability from moment to moment. Much of this variability may reflect inadequately controlled experimental variables, such as word memorability, past practice and subject fatigue. Alternatively, stochastic variability in performance may largely reflect the efficiency of endogenous neural processes that govern memory function. To help adjudicate between these competing views, the authors conducted a multisession study in which subjects completed 552 trials of a delayed free-recall task. Applying a statistical model to predict variability in each subject’s recall performance uncovered modest effects of word memorability, proactive interference, and other variables. In contrast to the limited explanatory power of these experimental variables, performance on the prior list strongly predicted current list recall. These findings suggest that endogenous factors underlying successful encoding and retrieval drive variability in performance. (PsycINFO Database Record

Concepts: Scientific method, Psychology, Future, Neuroscience, Memory, Theory, Storage, Interference theory


Learning and memory impairments are common in multiple sclerosis (MS) and may be related to difficulty acquiring (encoding or consolidating) new information. We evaluate the role of retroactive interference and investigate whether minimizing interference immediately following encoding (early during consolidation) will improve MS participants' ability to remember new verbal information. Additionally, we investigate processing speed differences between memory-impaired and unimpaired participants and present an exploratory analysis of how the dual-components of working memory (capacity vs. processing) relate to memory impairment.

Concepts: Multiple sclerosis, Memory, Memory processes, Interference theory


The current study used event-related brain potentials (ERPs) to explore whether self-reported trait impulsivity in healthy individuals might be differentially related to proactive and reactive interference control. Participants with high and low impulsivity (HI and LI, respectively) performed a modified version of the prime-target interference task. Proactive interference control was induced in the mostly incongruent (MI) context and reactive interference control was induced in the mostly congruent (MC) context. Although the behavioral data revealed no difference between HI and LI individuals in terms of the interference effects (incongruent - congruent) under both contexts, the ERP results showed that impulsivity has a different influence on the interference effects under different task contexts. In the MC context, the interference effects on the medial frontal negativity (MFN) and the negative sustained potential (N-SP) were greater, while that on the positive sustained potential (P-SP) were smaller in the HI compared to those in the LI group. This suggests that high levels of impulsivity might be associated with a reduced efficiency of the processes supporting reactive control to resolve interference when interference is not expected. In contrast, the three ERP indices (MFN, P-SP, and N-SP) of interference processing in the MI context were insensitive to variations in impulsivity. This suggests that HI individuals might be as effective as LI individuals in recruiting proactive control for sustained active maintenance of task goals to anticipate and prevent interference throughout the experimental blocks where interference occurs frequently. In conclusion, these results indicate that impulsivity has a more negative influence on reactive interference control than on proactive interference control.

Concepts: Management, Potential, Event-related potential, ConTeXt, Interference theory


Retrieval of target information can cause forgetting for related, but non-retrieved, information - retrieval-induced forgetting (RIF). The aim of the current studies was to examine a key prediction of the inhibitory account of RIF - interference dependence - whereby ‘strong’ non-retrieved items are more likely to interfere during retrieval and therefore, are more susceptible to RIF. Using visual objects allowed us to examine and contrast one index of item strength -object typicality, that is, how typical of its category an object is. Experiment 1 provided proof of concept for our variant of the recognition practice paradigm. Experiment 2 tested the prediction of the inhibitory account that the magnitude of RIF for natural visual objects would be dependent on item strength. Non-typical objects were more memorable overall than typical objects. We found that object memorability (as determined by typicality) influenced RIF with significant forgetting occurring for the memorable (non-typical), but not non-memorable (typical), objects. The current findings strongly support an inhibitory account of retrieval-induced forgetting.

Concepts: Object, Memory processes, Dependency, Interference, Functor, Proof of concept, Interference theory


Many studies concerned with misinformation correction during learning report that delayed corrective feedback is superior to immediate feedback. However, the mechanism for this effect has not been confirmed. The interference-perseveration theory predicts that immediate feedback following participants' wrong responses elicits proactive interference that deteriorates acquisition of feedback information. In contrast, delayed feedback following errors leads to participants' forgetting these errors during the delay period; consequently, in the latter, interference should decline leading to superior acquisition of corrective information. However, results of these studies have been inconsistent. The present study manipulated whether initial errors were visually cued before feedback (no error-cueing, error-cueing) along with the timing of the feedback (immediate, delayed). The interference-perseveration theory predicts that when errors are not cued, delayed feedback should result in superior acquisition of correct information compared to immediate feedback. When errors are cued, proactive interference should effect a deterioration in acquisition of corrective feedback. Results confirmed neither of these predictions, thus challenging the interference-perseveration hypothesis. Moreover, additional analysis suggested that memory for errors has the ability to enhance the retention of correct answers and it does not hinder recall.

Concepts: Scientific method, Linguistics, Delay, Tom DeLay, Typography, Memory processes, Leading, Interference theory