Competition between Memory and Perceptual Tasks Involving Physically Similar Stimuli

Background: The model of performance in short-term memory (STM) tasks that has been most influential in cognitive neuropsychological work on deficits of STM is the “working memory” model mainly associated with the work of Alan Baddeley and his colleagues. Aim: This paper reviews the model. We examine the development of this theory in studies that account for STM performances in normal (non-brain-damaged) individuals, and then review the application of this theory to neuropsychological cases and specifications, modifications, and extensions of the theory that have been suggested on the basis of these cases. Our approach is to identify the major phenomena that have been discussed and to examine selected papers dealing with those phenomena in some detail. Main Contribution: The main contribution is a review of the WM model that includes both normative and neuropsychological data. Conclusions: We conclude that the WM model has many inconsistencies and empirical inadequacies, and that cognitive neuropsychologists might benefit from considering other models when they attempt to describe and explain patients' performances on STM tasks.

Contributions of language and memory demands to verbal memory performance in language-learning disabilities

Storage-oriented memory span tasks with no explicit concurrent processing are usually referred as short-term memory (STM) tasks, whereas tasks involving storage plus concurrent processing requirements are designated as working memory (WM) tasks. The present study explores a question that remains unsolved: Do STM and WM tasks clearly tap distinguishable theoretical constructs? For that purpose, a large sample of 403 participants was tested through 12 diverse memory span tasks. Half of those tasks are widely accepted as measures of STM, whereas the other half measure WM. The results show that STM and WM share largely overlapping underlying capacity limitations, suggesting that all memory span tasks tap essentially the same construct. Some implications are discussed.

Use of phonological coding during reading and short-term memory tasks was examined in 12 participants with congenital speech impairments who had reading grade levels of 3.0 or better. Six of the participants had no intelligible speech (anarthria) and six had moderate to severe speech production impairments (dysarthria). All 12 participants were capable of judging the homophony of printed words and nonwords, indicating that accurate phonological coding of text can occur in the absence of speech. Moreover, five participants with dysarthria and two with anarthria appeared to employ phonological coding in short-term memory tasks, as indicated by a phonological similarity effect in serial order memory, and also more weakly by a word length effect in serial order memory. These data indicate that persons with severe congenital speech impairments can learn to use phonological coding during reading and short-term memory tasks; articulatory coding is therefore not a necessary part of the phonological coding process in either word identification or short-term memory. In this study, four of the participants with anarthria did not engage in phonological coding during short-term memory tasks. These participants had more severe deficits in identifying printed words than other participants. Possible explanations of these individual differences are discussed.

Extant research has demonstrated strong contextual dependencies in reproducing magnitudes of perceptual stimuli from short-term memory. Two experiments examined how context as defined by (a) the mean of the distribution, (b) stimulus ranks, (c) values of anchor stimuli used in the reproduction task, and (d) values from the most recent trial operate on estimates of square size. Experiment 1 demonstrated distributional contrast effects on ratings of squares and distributional assimilation effects on reproduction of squares from short-term memory for the same participants. The fit of a modified version of the category adjustment model demonstrated reliable effects of the running mean, start anchors, and previous stimulus on reproduction bias. In Experiment 2, participants first learned to associate labels with squares, then reproduced square sizes based on the label cues, a long-term memory task, followed by a reproduction from short-term memory task as in Experiment 1. Results for the short-term memory task were largely consistent with Experiment 1. Results for the long-term memory task showed a very different pattern of effects, with larger reproduced sizes when squares were drawn from positively skewed rather than negatively skewed distributions. This contrast effect was explained by a modified range-frequency model as the result of rank encoding of square values along with displacement away from the running mean and shifts towards the prior response and start anchors. The combined results identify multiple sources of context effects in estimation that depend critically on memory retrieval factors and show how they can be incorporated into existing models.

A reliable and unobtrusive quantification of changes in cortical activity during short-term memory task can be used to evaluate the efficacy of interfaces and to provide real-time user-state information. In this article, we investigate changes in electroencephalogram signals in short-term memory with respect to the baseline activity. The electroencephalogram signals have been analyzed using 9 linear and nonlinear/dynamic measures. We applied statistical Wilcoxon examination and Davis-Bouldian criterion to select optimal discriminative features. The results show that among the features, the permutation entropy significantly increased in frontal lobe and the occipital second lower alpha band activity decreased during memory task. These 2 features reflect the same mental task; however, their correlation with memory task varies in different intervals. In conclusion, it is suggested that the combination of the 2 features would improve the performance of memory based neurofeedback systems.

Short-term and working memory impairments in aphasia

An experiment is reported in which regional cerebral blood flow (rCBF) as measured using positron emission tomography (PET) as participants performed conceptual and perceptual memory tasks. Blood flow during two conceptual tests of semantic cued recall and semantic association was compared to a control condition in which participants made semantic associations to nonstudied words. Analogously, rCBF during two perceptual tasks of word fragment cued recall and word fragment completion was compared to a word fragment nonstudied control condition. A direct comparison of conceptual and perceptual tasks showed that conceptual tasks activated medial and lateral left hemisphere in frontal and temporal regions as well as the lateral aspect of bilateral inferior parietal lobule. Perceptual tasks, in contrast, produced relatively greater activation in right frontal and temporal cortex as well as bilateral activation in more posterior regions. Comparisons of the memory tasks with their control conditions revealed memory-specific deactivations in left medial and superior temporal cortex as well as left frontal cortex for both conceptual tasks. In contrast, memory-specific deactivations for both perceptual fragment completion tests were localized in posterior regions including occipital cortex. Results from this and other functional imaging experiments provide evidence that conceptual and perceptual memory processes are subserved, at least in part, by different neurological structures in the human brain.

Frequency judgments for distractor items in a short-term memory task: Instructional variation and adult age differences

Cognitive offloading is the process of recording information onto an external source (i.e., a piece of paper) to reduce short-term memory demands. People engage in cognitive offloading to be able to recall more information accurately [1]. The capacity for short-term memory is typically 7+/−2 items [2], but the number of items that can be accurately remembered decreases as the complexity of the information increases. As a result, people are more likely to engage in cognitive offloading when the memory task is difficult. Most cognitive offloading studies have used paper as the External Medium [1, 3]. People, however, may not have a pen and paper readily available to record information. Due to the increase of mobile technology, though, people are more likely to carry around mobile devices such as smartphones and tablets. Mobile devices can be used as a convenient medium to offload information. The present study examined if use of mobile technology would increase participants’ offloading behaviors and recall accuracy compared to using paper for recording information. Results indicated that although all tablet features were available (e.g., swiping, voice recording), participants engaged in less cognitive offloading when using tablets compared to paper, and this resulted in lower recall performance for the tablet condition. Implications of these findings are discussed.

Short term memory and working memory in blind versus sighted children

Associations Between Key Language-Related Measures in Typically Developing School-Age Children

Individual Differences in Short-Term Memory

ABSTRACTThe goal of the current study was to examine bilinguals' phonological short-term and working memory performance in their native/first (L1) and second (L2) languages. Korean–English bilinguals were tested in both Korean (L1) and English (L2). Short-term memory (STM) was measured via a nonword repetition task, where participants repeated nonwords that increased in length. Working memory (WM) was measured via a complex task, where the nonword repetition task was combined with an animacy judgment task. In general, bilinguals performed better on the STM task than on the WM task, and with shorter nonwords than with longer nonwords. Results also revealed that L1 STM performance was superior to L2 STM performance, but only for the longest nonwords, whereas L1 WM performance was superior to L2 WM performance across all length levels. In addition, correlation analyses between bilinguals' L1 and L2 performance revealed stronger cross-linguistic associations for the WM task than for the STM task. Together, the findings suggest that WM tasks may engage domain-general central executive processes in bilinguals, whereas STM skills may depend on language-specific knowledge in the L1 and the L2.

The current study examined the effect of background music and noise on the cognitive task performance and tested the gender difference. Ninety-one participants completed (53 female, 38 male) two kinds of cognitive tasks: one was simple task (perception task), the other was complex task (spatial reasoning task, which had two levels: easy & difficult). Participants were randomly assigned to one of five background sound conditions: country music, jazz music, rock music, traffic noise, and silence. We used both latency and error rate as cognitive performance. A three-way significant interaction among background sound, cognitive task and gender was found. The differential distraction of background sound was significant on performance of perception and spatial reasoning tasks. Participants spent more time completing the cognitive tasks when in the presence of rock, and made more mistakes when in the presence of noise. This distraction pattern was only found in male participants; Female participants were not distracted by background sound. The implication of these findings was discussed.