Working memory, short-term memory, and general fluid intelligence: a latent-variable approach.

A study was conducted in which 133 participants performed 11 memory tasks (some thought to reflect working memory and some thought to reflect short-term memory), 2 tests of general fluid intelligence, and the Verbal and Quantitative Scholastic Aptitude Tests. Structural equation modeling suggested that short-term and working memories reflect separate but highly related constructs and that many of the tasks used in the literature as working memory tasks reflect a common construct. Working memory shows a strong connection to fluid intelligence, but short-term memory does not. A theory of working memory capacity and general fluid intelligence is proposed: The authors argue that working memory capacity and fluid intelligence reflect the ability to keep a representation active, particularly in the face of interference and distraction. The authors also discuss the relationship of this capability to controlled attention, and the functions of the prefrontal cortex.     

Similarities and differences between mind-wandering and external distraction: A latent variable analysis of lapses of attention and their relation to cognitive abilities

The current study examined the extent to which task-unrelated thoughts represent both vulnerability to mind-wandering and susceptibility to external distraction from an individual difference perspective. Participants performed multiple measures of attention control, working memory capacity, and fluid intelligence. Task-unrelated thoughts were assessed using thought probes during the attention control tasks. Using latent variable techniques, the results suggested that mind-wandering and external distraction reflect distinct, yet correlated constructs, both of which are related to working memory capacity and fluid intelligence. Furthermore, the results suggest that the common variance shared by mind-wandering, external distraction, and attention control is what primarily accounts for their relation with working memory capacity and fluid intelligence. These results support the notion that lapses of attention are strongly related to cognitive abilities.     

Suppression of intrusive thoughts and working memory capacity in repressive coping

Previous research using a thought suppression paradigm found that repressors are more skilled in suppressing anxious autobiographical thoughts than low anxious, high anxious, and defensive high anxious people. Another line of research showed that individual differences in working memory capacity are related to the ability to intentionally suppress intrusive thoughts. This study aimed at combining these findings and sought to investigate whether repressors' superior ability to suppress intrusive thoughts is related to a larger working memory capacity. Results indicate that in a thought suppression paradigm, repressors report fewer intrusive thoughts for their most anxious experiences than participants in the 3 other subgroups. Furthermore, the superior ability of repressors to avoid intrusive thoughts can be explained largely by their higher working memory capacity.     

PROCESSING SPEED, WORKING MEMORY, AND FLUID INTELLIGENCE:

Abstract— Processing speed, working memory capacity, and fluid intelligence were assessed in a large sample ( N = 214) of children, adolescents, and young adults (ages 7 to 19 years) Results of path analyses revealed that almost half of the age-related increase in fluid intelligence was mediated by developmental changes in processing speed and marking memory and nearly three fourths of the improvement in working memory was mediated by developmental changes in processing speed Moreover, even when age-related differences in speed, working memory and fluid intelligence were statistically controlled, individual differences in speed had a direct effect on working memory capacity which, in turn was a direct determinant of individual differences in fluid intelligence     

There’s more to the working memory capacity—fluid intelligence relationship than just secondary memory

The present study examined the claim that secondary memory processes account for the correlation between working memory capacity and fluid intelligence via a latent variable analysis. In the present study, participants performed multiple measures of secondary memory, working memory capacity, and fluid intelligence. Structural equation modeling suggested that both secondary memory and working memory capacity account for unique variance in fluid intelligence. These results are inconsistent with recent claims that working memory capacity does not account for variance in fluid intelligence over and above what is accounted for by secondary memory. Rather, the results are consistent with models of working memory capacity that suggest that both maintenance and retrieval processes are needed to account for the substantial relation between working memory capacity and fluid intelligence.     

Ageing and thought suppression performance: Its relationship with working memory capacity,habitual thought suppression and mindfulness

A study investigated how the ability to suppress thoughts in the laboratory was affected by type of thought suppressed (positive, negative, neutral), participants’ age and working memory capacity (WMC). Linked variables (Use of thought suppression, social desirability, and mindfulness) were measured to assess whether they modified susceptibility to thought intrusion.Younger, middle aged and older adults suppressed three different valenced thoughts in a counterbalanced order for 5-min per thought. Participants then completed a WMC task and questionnaire measures of the linked variables.Valence had no effect on intrusions. WMC was positively related to intrusions; higher WMC corresponded to greater intrusions. Age was negatively related to intrusions; with increasing age intrusions decreased. Hierarchical regression showed only age and backward digit span (WMC) significantly predicted intrusions. The relationship between WMC and intrusions was not moderated by age. WMC and age both independently predict level of intrusion, and no synergistic effect was found.     

Fluid intelligence, working memory and executive functioning

The causes underlying the correlation between working memory and fluid intelligence remain unknown. There are some researchers who argue that the answer can be found on the presumed executive component of working memory. However, the available empirical evidence is far from conclusive. The present study tested a sample of 229 participants. Intelligence, working memory, and executive functioning were measured by one analytic reasoning test (TRASI), a dual task combining a primary task of deductive reasoning with a secondary task of counting, and the Tower of Hanoi task, respectively. All the 3 measures were computer administered. The results indicate that the shared variance between executive functioning and working memory do not account for the relationship between intelligence and working memory. Some theoretical implications are discussed.     

Working memory – not processing speed – mediates fluid intelligence deficits associated with attention deficit/hyperactivity disorder symptoms

Attention deficit/hyperactivity disorder (ADHD) is a psychological condition characterized by inattention and hyperactivity. Cognitive deficits are commonly observed in ADHD patients, including impaired working memory, processing speed, and fluid intelligence, the three of which are theorized to be closely associated with one another. In this study, we aimed to determine if decreased fluid intelligence was associated with ADHD, and was mediated by deficits in working memory and processing speed. This study tested 142 young adults from the general population on a range of working memory, processing speed, and fluid intelligence tasks, and an ADHD self‐report symptoms questionnaire. Results showed that total and hyperactive ADHD symptoms correlated significantly and negatively with fluid intelligence, but this association was fully mediated by working memory. However, inattentive symptoms were not associated with fluid intelligence. Additionally, processing speed was not associated with ADHD symptoms at all, and was not uniquely predictive of fluid intelligence. The results provide implications for working memory training programs for ADHD patients, and highlight potential differences between the neuropsychological profiles of ADHD subtypes.     

Why is working memory related to intelligence? Different contributions from storage and processing

Domain-specific contributions of working memory (WM), short-term memory (STM), and executive functioning (EF) to individual differences in intelligence were analysed using a latent variable approach. A sample of 345 participants completed a battery of 24 tests tapping the constructs of interests as comprehensively as possible. Visuospatial and verbal STM and WM tasks were administered along with three subcomponents of EF, namely inhibition, planning, and shifting. Intelligence was assessed by non-verbal/abstract/fluid intelligence (Gf) and verbal/crystallised intelligence (Gc) standardised tests. Structural equation modelling results show that EF is the main predictor of Gf, whereas verbal STM is the main predictor of Gc. Storage and processing providing different contributions to the prediction of Gf and Gc supports the view that both short-term storage and executive functioning account for the relationship between WM and intelligence. This main conclusion stresses the importance of acknowledging core cognitive constructs as being hierarchical systems with general and domain-specific mechanisms.     

Using the process dissociation procedure to estimate recollection and familiarity in working memory: An experimental and individual differences investigation

Numerous studies have found that working memory capacity and perceptual speed predict variation in fluid intelligence. Within the cognitive ageing literature, perceptual speed accounts for substantial ageing variance in working memory capacity and fluid intelligence. However, within young adults, the interrelationships among these three abilities are less clear. The current work investigated these relationships via confirmatory factor analyses and structural equation modelling using tasks with verbal, spatial, and numerical content. The results indicate that working memory capacity and perceptual speed were not related in a large, cognitively diverse sample of young adults. However, both working memory capacity and perceptual speed accounted for unique variance in fluid intelligence. The results are discussed in relation to previous research with young and older adults.     

An account of the relationship between fluid intelligence and complex learning in considering storage capacity and executive attention

Although fluid intelligence and complex learning are conceptualized differently and assessed by apparently different measures, both theoretical accounts and empirical evidence suggest a relationship between the two constructs. In this study, major working memory aspects including the storage capacity and executive attention were proposed to account for the relationship between fluid intelligence and complex learning. A sample of 184 participants completed fluid intelligence and complex learning scales, as well as working memory measures that each included two or three treatment levels differing in the demands on capacity or executive control. The differences among the treatment levels provided a favorable precondition for employing fixed-links models to separate the core processes of storage capacity or executive attention from the auxiliary processes. Results indicated that both storage capacity and executive attention contributed significantly to fluid intelligence and complex learning. A further analysis showed that the two working memory aspects, particularly the storage capacity, accounted for most of the shared variance between fluid intelligence and complex learning.     

Working Memory,Fluid Intelligence,and Attention Are Predictors of Multitasking Performance,but Polychronicity and Extraversion Are Not

This study explored predictors of multitasking performance. Based on cognitive psychology research, attention and working memory were assumed to be predictors. Fluid intelligence, polychronicity (as the preference for multitasking and the belief that their preference is the best way to handle things), and Extraversion were argued to be additional predictors. Multitasking performance was measured with the scenario "Simultaneous capacity/Multi-tasking (SIMKAP)" (n = 122). Hierarchical multiple regression analyses revealed that working memory was the most important predictor in addition to attention and fluid intelligence. The latter two constructs contributed significantly to the explained variance, but to a lesser extent. Polychronicity was not a significant predictor, nor was Extraversion. Implications for personnel selection and for time management are discussed.     

A dissociation between the sense of familiarity and access to semantic information concerning familiar people

In the current study we examined the relationship between working memory capacity, inhibition/susceptibility to interference and fluid intelligence, measured by the Raven's Progressive Matrices (PM38), comparing groups of young (aged 18–35), young-old (aged 65–74), and old-old (aged 75–86) participants. Groups were administered two working memory tasks tapping into different mechanisms involved in working memory. The ability to control for irrelevant information was measured both considering memory errors (intrusion errors) in a working memory task and an index of susceptibility to interference obtained with a variant of the Brown-Peterson task. Regression analyses showed that the classical working memory measure was the most potent predictors of the Raven's score. Susceptibility to interference and intrusions errors contributed, but to a lower extent, to the Raven explained variance. These results confirm that working memory shares cognitive aspects with the fluid intelligence measure considered, whereas the role of inhibition to Raven scores is still in need of better evidence.     

Quantity,not quality: the relationship between fluid intelligence and working memory capacity

A key motivation for understanding capacity in working memory (WM) is its relationship with fluid intelligence. Recent evidence has suggested a two-factor model that distinguishes between the number of representations that can be maintained in WM and the resolution of those representations. To determine how these factors relate to fluid intelligence, we conducted an exploratory factor analysis on multiple number-limited and resolution-limited measures of WM ability. The results strongly supported the two-factor model, with fully orthogonal factors accounting for performance in the number-limited and resolution-limited conditions. Furthermore, the reliable relationship between WM capacity and fluid intelligence was exclusively supported by the number factor (r=.66), whereas the resolution factor made no reliable contribution (r=−.05). Thus, the relationship between WM capacity and standard measures of fluid intelligence is mediated by the number of representations that can be simultaneously maintained in WM, rather than by the precision of those representations.     

Working memory, inhibition, and fluid intelligence as predictors of performance on Tower of Hanoi and London tasks

The contributions of working memory, inhibition, and fluid intelligence to performance on the Tower of Hanoi (TOH) and Tower of London (TOL) were examined in 85 undergraduate participants. All three factors accounted for significant variance on the TOH, but only fluid intelligence accounted for significant variance on the TOL. When the contribution of fluid intelligence was accounted for, working memory and inhibition continued to account for significant variance on the TOH. These findings support argument that fluid intelligence contributes to executive functioning, but also show that the executive processes elicited by tasks vary according to task structure.     

Task rules, working memory, and fluid intelligence

Many varieties of working memory have been linked to fluid intelligence. In Duncan et al. (Journal of Experimental Psychology:General 137:131-148, 2008), we described limited working memory for new task rules: When rules are complex, some may fail in their control of behavior, though they are often still available for explicit recall. Unlike other kinds of working memory, load is determined in this case not by real-time performance demands, but by the total complexity of the task instructions. Here, we show that the correlation with fluid intelligence is stronger for this aspect of working memory than for several other, more traditional varieties-including simple and complex spans and a test of visual short-term memory. Any task, we propose, requires construction of a mental control program that aids in segregating and assembling multiple task parts and their controlling rules. Fluid intelligence is linked closely to the efficiency of constructing such programs, especially when behavior is complex and novel.     

Working memory and fluid intelligence in young children

The present study investigates how working memory and fluid intelligence are related in young children and how these links develop over time. The major aim is to determine which aspect of the working memory system—short-term storage or cognitive control—drives the relationship with fluid intelligence. A sample of 119 children was followed from kindergarten to second grade and completed multiple assessments of working memory, short-term memory, and fluid intelligence. The data showed that working memory, short-term memory, and fluid intelligence were highly related but separate constructs in young children. The results further showed that when the common variance between working memory and short-term memory was controlled, the residual working memory factor manifested significant links with fluid intelligence whereas the residual short-term memory factor did not. These findings suggest that in young children cognitive control mechanisms rather than the storage component of working memory span tasks are the source of their link with fluid intelligence.     

The unique contributions of the facilitation of procedural memory and working memory to individual differences in intelligence

Individual differences in working memory account for a substantial portion of individual differences in complex cognitive processes (e.g., comprehension) and fluid intelligence. However, a large portion of the variance in fluid intelligence and comprehension is unexplained. The current investigation was conducted to evaluate whether individual differences in the facilitation of procedural memory accounts for unique variance in intelligence not accounted for by working memory. To measure variability in the facilitation of procedural memory, we used a task that required participants to first classify exemplars of two categories; facilitation was then operationalized by subsequent improvements in the speed of classifying new exemplars from those categories (i.e., an operation-specific memory procedure). Three measures of each focal construct (facilitation in procedural memory, working memory, comprehension and fluid intelligence) were administered to 256 participants. We used structural equation modeling to examine the relationships among these latent variables. Working memory did account for variance in fluid intelligence and comprehension, but most important, individual differences in facilitation of procedural memory accounted for unique variance in fluid intelligence and comprehension.     

Attention,Memory, Intrusive Thoughts,and Acceptance in PTSD: An Update on the Empirical Literature for Clinicians

Information processing theory suggests that cognitive changes following trauma are common and hypothesized to have an impact on attention, memory, and intrusive thoughts. There is an ever-expanding empirical literature where cognitive features of posttraumatic stress disorder (PTSD) are being explored. However, it can sometimes be difficult for front-line clinicians to stay abreast of this literature and how it impacts the treatment s/he provides. The goal of this paper is to provide an overview of some recent basic and applied research on information processing in PTSD and the implications of these findings for cognitive-behavioral clinicians. In particular, we explore recent findings regarding attention, memory, intrusive thoughts/thought suppression, and acceptance as they relate to clinical work in patients with PTSD.     

Can fluid intelligence be reduced to ‘simple’ short-term storage?

Much is written regarding the associations between human intelligence and cognition. However, it is unusual to find comprehensive studies. Here twenty four measures tapping eight cognitive abilities and skills are considered for assessing a sample of one hundred and eighty five young adults. The simultaneous relationships among fluid, crystallized, and spatial intelligence, along with short-term memory, working memory capacity, executive updating, attention, and processing speed are analyzed using a latent-variable approach. The key findings show that (a) short-term storage, working memory, and updating are hardly distinguishable, and (b) fluid intelligence is near-perfectly correlated with these three cognitive functions. It is concluded that this nuclear intelligence component can be largely identified with basic and general short-term storage processes, namely, encoding, maintenance, and retrieval.