The role of working memory in syntactic sentence realization: A modeling & simulation approach

This paper examines the effects of working memory size in incremental grammatical encoding during language production. Our experiment tests different variants of a computational-cognitive model that combines an empirically validated framework of general cognition, ACT-R, with a linguistic theory, Combinatory Categorial Grammar. The model is induced from a corpus of spoken dialogue. This methodology facilitates comparison of different strategies and working memory capacities according to the similarity of the model’s produced sentences to the corpus sentences. The experiment presented shows that while having more working memory available improves performance, using less working memory during realization does as well, even after controlling sentence length. Sentences realized with a more incremental strategy also appear to more closely track the naturalistic data. As high incrementality is correlated with low working memory usage, this study offers a possible mechanism by which syntactic incrementality can be explained. Finally, this paper proposes a multi-disciplinary modeling and simulation-based approach to empirical psycholinguistic inquiry.     

Short-term memory impairment in vestibular patients can arise independently of psychiatric impairment,fatigue, and sleeplessness

Vestibular dysfunction is associated with visual short-term memory impairment; however, it remains unclear if this impairment arises as a direct result of the vestibular dysfunction or is a consequence of comorbid changes in mood, affect, fatigue, and/or sleep. To this end, we assessed the concurrence and interdependence of these comorbidities in 101 individuals recruited from a tertiary balance clinic with a neuro-otological diagnosis. Over fifty per cent of the sample showed reduced visuospatial short-term memory, 60% and 37% exceeded cut-off on the Beck Anxiety and Depression Inventories, respectively, 70% exceeded cut-off on the Fatigue Severity Scale, 44% reported daytime sleepiness on the Epworth Sleepiness Scale, and 78% scored above cut-off on the Pittsburgh Sleep Quality Index. The high concurrence of these symptoms gives reason to infer the existence of a vestibular cognitive affective syndrome. Structural equation modelling indicated that the significant statistical association between general unassisted posture (a marker of chronic vestibular dysfunction and strong predictor of falls risk) and short-term memory was not mediated by mood and wakefulness. Instead, the memory impairment related more directly to vestibular dysfunction. From a rehabilitation perspective, the implication is that if the vestibular disorder is treated successfully then the memory problem will likewise improve.     

Deficits in prospective memory following damage to the medial subdivision of the mediodorsal thalamic nucleus

Identifying the neurocognitive mechanisms that lead individuals remembering to execute an intention at the right moment (prospective memory, PM) and how such mechanisms are influenced by the features of that intention is a fundamental theoretical challenge. In particular, the functional contribution of subcortical regions to PM is still unknown. This study was aimed at investigating the role of the medial subdivision of the mediodorsal thalamic nucleus (mMDT) in PM, with particular focus on the processes that are mediated by the projections from/to this structure. We analysed the performance of a patient (OG) with a right-sided lesion involving the mMDT in a series of PM tasks that varied for focality (i.e., overlapping of processes for the PM and ongoing tasks) and emotional valence of the stimuli, comparing the patient's performance with that of a control group. We found that the mMDT damage led to deficits in PM that were modulated by focality and emotional valence. OG indeed showed: a greater cost in the ongoing performance when a non-focal PM task was added; a slowing down in retrieving the intentions, in particular when these were associated with focal PM cues; an abnormal performance in the task with positive PM cues. Our findings provide evidence of a contribution of mMDT to PM and suggest a modulation of prefrontal-dependent strategic monitoring and a possible interaction with the limbic structures in the integration of emotion and PM processes. They also give support to the still controversial idea that connections with the perirhinal cortex mediate familiarity-based recognition.     

Why Higher Working Memory Capacity May Help You Learn: Sampling,Search, and Degrees of Approximation

Algorithms for approximate Bayesian inference, such as those based on sampling (i.e., Monte Carlo methods), provide a natural source of models of how people may deal with uncertainty with limited cognitive resources. Here, we consider the idea that individual differences in working memory capacity (WMC) may be usefully modeled in terms of the number of samples, or “particles,” available to perform inference. To test this idea, we focus on two recent experiments that report positive associations between WMC and two distinct aspects of categorization performance: the ability to learn novel categories, and the ability to switch between different categorization strategies (“knowledge restructuring”). In favor of the idea of modeling WMC as a number of particles, we show that a single model can reproduce both experimental results by varying the number of particles—increasing the number of particles leads to both faster category learning and improved strategy‐switching. Furthermore, when we fit the model to individual participants, we found a positive association between WMC and best‐fit number of particles for strategy switching. However, no association between WMC and best‐fit number of particles was found for category learning. These results are discussed in the context of the general challenge of disentangling the contributions of different potential sources of behavioral variability.     

Keeping the Result in Sight and Mind: General Cognitive Principles and Language‐Specific Influences in the Perception and Memory of Resultative Events

We study how people attend to and memorize endings of events that differ in the degree to which objects in them are affected by an action: Resultative events show objects that undergo a visually salient change in state during the course of the event (peeling a potato), and non‐resultative events involve objects that undergo no, or only partial state change (stirring in a pan). We investigate general cognitive principles, and potential language‐specific influences, in verbal and nonverbal event encoding and memory, across two experiments with Dutch and Estonian participants. Estonian marks a viewer's perspective on an event's result obligatorily via grammatical case on direct object nouns: Objects undergoing a partial/full change in state in an event are marked with partitive/accusative case, respectively. Therefore, we hypothesized increased saliency of object states and event results in Estonian speakers, as compared to speakers of Dutch. Findings show (a) a general cognitive principle of attending carefully to endings of resultative events, implying cognitive saliency of object states in event processing; (b) a language‐specific boost on attention and memory of event results under verbal task demands in Estonian speakers. Results are discussed in relation to theories of event cognition, linguistic relativity, and thinking for speaking.     

Cognitive Offloading: Structuring the Environment to Improve Children's Working Memory Task Performance

Research has shown that adults can engage in cognitive offloading, whereby internal processes are offloaded onto the environment to help task performance. Here, we investigate an application of this approach with children, in particular children with poor working memory. Participants were required to remember and recall sequences of colors by placing colored blocks in the correct serial order. In one condition the blocks were arranged to facilitate cognitive offloading (i.e., grouped by color), whereas in the other condition they were arranged randomly. Across two experiments (total N = 166) the ordered condition improved task performance for children with low working memory ability. In addition, participants in Experiment 2 rated the difficulty of the two arrangements and performed a further condition in which they were given an opportunity to freely arrange the blocks before completing the task. Despite performing better in the ordered condition, children with low working memory ability did not rate the ordered arrangement as easier, nor did they choose an ordered arrangement when given the opportunity to do so. This research shows that cognitive offloading can also be a useful process in populations other than typical adults, and the implications of this work for supporting children with poor working memory are discussed.     

Executive functions predict conceptual learning of science

We examined the relationship between executive functions and both factual and conceptual learning of science, specifically chemistry, in early adolescence. Sixty‐three pupils in their second year of secondary school (aged 12–13 years) participated. Pupils completed tasks of working memory (Spatial Working Memory), inhibition (Stop‐Signal), attention set‐shifting (ID/ED), and planning (Stockings of Cambridge), from the CANTAB. They also participated in a chemistry teaching session, practical, and assessment on the topic of acids and alkalis designed specifically for this study. Executive function data were related to (1) the chemistry assessment which included aspects of factual and conceptual learning and (2) a recent school science exam. Correlational analyses between executive functions and both the chemistry assessment and science grades revealed that science achievements were significantly correlated with working memory. Linear regression analysis revealed that visuospatial working memory ability was predictive of chemistry performance. Interestingly, this relationship was observed solely in relation to the conceptual learning condition of the assessment highlighting the role of executive functions in understanding and applying knowledge about what is learned within science teaching.     

How a high working memory capacity can increase proactive interference

Previous findings suggested that a high working memory capacity (WMC) is potentially associated with a higher susceptibility to proactive interference (PI) if the latter is measured under high cognitive load. To explain such a finding, we propose to consider susceptibility to PI as a net effect of individual executive processes and the intrinsic potential for PI. With the latter, we refer to the amount of information that is activated at a given time and that has the potential to exert PI subsequently. In two studies deploying generalized linear mixed models, susceptibility to PI was modeled as the decline of performance over trials of a complex span task. The results revealed that a higher WMC was associated with a higher susceptibility to PI. Moreover, the number of stimuli recalled in one trial as a proxy variable for the intrinsic potential for PI negatively affected memory performance in the subsequent trial.