Competition accumulates in successive retrieval of proper names

Proper names are especially prone to retrieval failures and tip-of-the-tongue states (TOTs)-a phenomenon wherein a person has a strong feeling of knowing a word but cannot retrieve it. Current research provides mixed evidence regarding whether related names facilitate or compete with target-name retrieval. We examined this question in two experiments using a novel paradigm where participants either read a prime name aloud (Experiment 1) or classified a written prime name as famous or non-famous (Experiment 2) prior to naming a celebrity picture. Successful retrievals decreased with increasing trial number (and was dependent on the number of previously presented similar famous people) in both experiments, revealing a form of accumulating interference between multiple famous names. However, trial number had no effect on TOTs, and within each trial famous prime names increased TOTs only in Experiment 2. These results can be explained within a framework that assumes competition for selection at the point of lexical retrieval, such that successful retrievals decrease after successive retrievals of proper names of depicted faces of semantically similar people. By contrast, the effects of written prime words only occur when prime names are sufficiently processed, and do not provide evidence for competition but may reflect improved retrieval relative to a "don't know" response.

The Mechanisms Underlying Interference and Inhibition: A Review of Current Behavioral and Neuroimaging Research

The memory literature has identified interference and inhibition as two major sources of forgetting. While interference is generally considered to be a passive cause of forgetting arising from exposure to additional information that impedes subsequent recall of target information, inhibition concerns a more active and goal-directed cause of forgetting that can be achieved intentionally. Over the past 25 years, our knowledge of the neural mechanisms underlying both interference-induced and inhibition-induced forgetting has expanded substantially. The present paper gives a critical overview of this research, pointing out empirical gaps in the current work and providing suggestions for future studies.

Oscillatory Correlates of Selective Restudy

Prior behavioral work has shown that selective restudy of some studied items leaves recall of the other studied items unaffected when lag between study and restudy is short, but improves recall of the other items when lag is prolonged. The beneficial effect has been attributed to context retrieval, assuming that selective restudy reactivates the context at study and thus provides a retrieval cue for the other items (Bäuml, 2019). Here the results of two experiments are reported, in each of which subjects studied a list of items and then, after a short 2-min or a prolonged 10-min lag, restudied some of the list items. Participants' electroencephalography (EEG) was recorded during both the study and restudy phases. In Experiment 2, but not in Experiment 1, subjects engaged in a mental context reinstatement task immediately before the restudy phase started, trying to mentally reinstate the study context. Results of Experiment 1 revealed a theta/alpha power increase from study to restudy after short lag and an alpha/beta power decrease after long lag. Engagement in the mental context reinstatement task in Experiment 2 eliminated the decrease in alpha/beta power. The results are consistent with the view that the observed alpha/beta decrease reflects context retrieval, which became obsolete when there was preceding mental context reinstatement.

Buildup and release from proactive interference - Cognitive and neural mechanisms

Interference from related memories is generally considered one of the major causes of forgetting in human memory. The most prevalent form of interference may be proactive interference (PI), which refers to the finding that memory of more recently studied information can be impaired by the previous study of other information. PI is a fairly persistent effect, but numerous studies have shown that there can also be release from PI. PI buildup and release have primarily been studied using paired-associate learning, the Brown-Peterson task, or multiple-list learning. The review first introduces the three experimental tasks and, for each task, summarizes critical findings on PI buildup and release, from both behavioral and imaging work. Then, an overview is provided of suggested cognitive mechanisms operating on the encoding and retrieval stages as well as of neural correlates of these mechanisms. The results indicate that, in general, both encoding and retrieval processes contribute to PI buildup and release. Finally, empirical gaps in the current work are emphasized and suggestions for future studies are provided.

Electrophysiological evidence that release from proactive inhibition reflects late semantic processing

While proactive inhibition (PI) frequently occurs in response to novel stimuli due to interference from previously learned information, shifts in semantic category on a preceding trial lead to the attenuation of learning interference effects such as PI, resulting in significantly improved performance on short-term memory tasks. This study examined how the release from PI also leads to a reduction in semantic inhibition, as measured primarily through an event-related potential (ERP) electroencephalography (EEG) design. The study used Chinese characters denoting different categories (word nouns for categories such as plants, clothes, and flowers) to test short-term memory recall in a control group (same category/no PI release) and experimental group (different category/PI release). Both behavioral data (recall accuracy) and ERP responses for the N400 and Late Positive Component (LPC) at frontal, central, and parietal electrode sites were collected. Behaviorally, recall accuracy declined continuously on the initial three consecutive trials, regardless of group, while recall increased significantly on the last trial specifically for the experimental group, due to the shift in semantic category. We reported a significant interaction between group and electrode site for the LPC component, indicating that inhibition effects were still active for both groups at the initial memory encoding stage (corresponding to N400), with inhibition release in the experimental group occurring through later LPC processing. These results provide electrophysiological evidence that release from PI can be distinguished from semantic forms of processing through changes in amplitude over the course of learning.

Mindfulness improves verbal learning and memory through enhanced encoding

Recent research has begun to demonstrate the effectiveness of mindfulness in improving certain cognitive abilities, including verbal learning and memory. However, no research has investigated the potential mechanism by which mindfulness may improve verbal learning and memory. We examined encoding, consolidation, and retrieval as potential mechanisms by which learning and memory may be increased on a list learning test (Rey Auditory Verbal Learning Task; RAVLT). After dividing participants into either a mindfulness or a control condition, in which they listened to a 10-min audio tape, results found that the mindfulness condition significantly outperformed the control condition on every RAVLT trial. Using the Item-Specific Deficit Approach, we discovered that this enhanced verbal learning and memory was specifically due to a significantly enhanced encoding process for the mindfulness group, which fully mediated the relationship between the mindfulness condition and performance on the RAVLT. There were no differences between the conditions on consolidation or retrieval. Furthermore, these improvements were not accompanied by improvements in verbal fluency or attention. In a second study, we presented a mindfulness or control audio before the first RAVLT delayed free-recall trial and another one before the second RAVLT delayed free-recall trial in order to better determine the effect of mindfulness on consolidation and retrieval. The results replicated Study 1, in that neither consolidation nor retrieval were significantly affected by mindfulness. This research indicates that mindfulness may primarily improve verbal learning and memory through improved encoding processes.

Individual differences in working memory capacity and search efficiency

In two experiments, we examined how various learning conditions impact the relation between working memory capacity (WMC) and memory search abilities. Experiment 1 employed a delayed free recall task with semantically related words to induce the buildup of proactive interference (PI) and revealed that the buildup of PI differentially impacted recall accuracy and recall latency for low-WMC and high-WMC individuals. Namely, the buildup of PI impaired recall accuracy and slowed recall latency for low-WMC individuals to a greater extent than what was observed for high-WMC individuals. To provide a circumstance in which previously learned information remains relevant over the course of learning, Experiment 2 required participants to complete a multitrial delayed free recall task with unrelated words. Results revealed that with increased practice with the same word list, WMC-related differences were eventually eliminated in interresponse times (IRTs) and recall accuracy, but not recall latency. Thus, despite still accumulating larger search sets, low-WMC individuals searched LTM as efficiently as high-WMC individuals. Collectively, these results are consistent with the notion that under normal free recall conditions, low-WMC individuals search LTM less efficiently than do high-WMC individuals because of their reliance on noisy temporal-contextual cues at retrieval. However, it appears that under conditions in which previously learned items remain relevant at recall, this tendency to rely on vague self-generated retrieval cues can actually facilitate the ability to accurately and quickly recall information.

Changes in alpha activity reveal that social opinion modulates attention allocation during face processing

Participants' performance differs when conducting a task in the presence of a secondary individual, moreover the opinion the participant has of this individual also plays a role. Using EEG, we investigated how previous interactions with, and evaluations of, an avatar in virtual reality subsequently influenced attentional allocation to the face of that avatar. We focused on changes in the alpha activity as an index of attentional allocation. We found that the onset of an avatar's face whom the participant had developed a rapport with induced greater alpha suppression. This suggests greater attentional resources are allocated to the interacted-with avatars. The evaluative ratings of the avatar induced a U-shaped change in alpha suppression, such that participants paid most attention when the avatar was rated as average. These results suggest that attentional allocation is an important element of how behaviour is altered in the presence of a secondary individual and is modulated by our opinion of that individual.

Pupil dilation tracks the dynamics of mnemonic interference resolution

Mnemonic interference refers to the inability to retrieve a goal-relevant memory due to interference from goal-irrelevant memories. Understanding the causes of such interference and how it is overcome has been a central goal in the science of memory for more than a century. Here, we shed new light on this fundamental issue by tracking participants' pupil response when they encode and retrieve memories in the face of competing goal-irrelevant memories. We show that pupil dilation systematically increased in accordance with interference from competing memory traces when participants retrieved previously learned information. Moreover, our results dissociate two main components in the pupillary response signal: an early component, which peaked in a time window where the pupillary waveform on average had its maximum peak, and a late component, which peaked towards the end of the retrieval task. We provide evidence that the early component is specifically modulated by the cognitive effort needed to handle interference from competing memory traces whereas the late component reflects general task engagement. This is the first demonstration that mnemonic interference resolution can be tracked online in the pupil signal and offers novel insight into the underlying dynamics.

Working Memory Capacity as a Determinant of Proactive Interference and Auditory Distraction

Individual differences in working memory capacity are related to performance on a range of elemental and higher order cognitive tasks. The current experiment tests the assumptions of two theoretical approaches to working memory capacity: working memory as executive attention and working memory as temporary binding. These approaches are examined using a short-term updating task where proactive interference is manipulated, such that old responses have to be suppressed in favour of new responses. A second source of distraction is introduced by way of irrelevant, to-be-ignored background speech that accompanies presentation of the list items. This speech reinforces either the to-be-remembered item on the current list, or the to-be-suppressed item. Working memory capacity was significantly related to overall level of correct performance on the short-term task, and to the degree of proactive interference experienced. However, there was no evidence for individual differences in the ability to suppress the interfering foil, nor in priming effects associated with the irrelevant speech. The results provided little support for the working memory capacity as executive attention perspective, some evidence for the binding perspective, but also evidence supporting the fact that some effects of distraction are not under voluntary control.

Blocked vs. interleaved presentation and proactive interference in episodic memory

Although a number of theoretical accounts of proactive interference (PI) in episodic memory have been proposed, existing empirical evidence does not support conclusively a single view yet. In two experiments we tested the predictions of the temporal discrimination theory of PI against alternative accounts by manipulating the presentation schedule of study materials (lists blocked by category vs. interleaved). In line with the temporal discrimination theory, we observed a clear buildup of (and release from) PI in the blocked condition, in which all the lists of the same category were presented sequentially. In the interleaved condition, with alternating lists of different categories, a more gradual and smoother buildup of PI was observed. When participants were left free to choose their presentation schedule, they spontaneously adopted an interleaved schedule, resulting again in more gradual PI. After longer delays, we observed recency effects at the list level in overall recall and, in the blocked condition, PI-related effects. The overall pattern of findings agrees with the predictions of the temporal discrimination theory of PI, complemented with categorical processing of list items, but not with alternative accounts, shedding light on the dynamics and underpinnings of PI under diverse presentation schedules and over different time scales.