Is working memory capacity a causal factor in fluid intelligence?

Psychonomic Bulletin & Review - It is well established that measures of reasoning ability and of working memory capacity (WMC) correlate positively. However, the question of what explains this...     

Why is working memory related to fluid intelligence?

Nearly 1,000 adults performed a battery of cognitive tests and working memory tasks requiring simultaneous storage and processing of information. Because the amount of to-be-remembered information, or set size, varied randomly across trials, the relation between fluid intelligence and working memory could be examined across different levels of complexity and across successive trials in the working memory tasks. Strong influences of fluid intelligence were apparent in the simplest versions and on the initial trials in the working memory tasks, which suggests that the relation between working memory and fluid intelligence is not dependent on the amount of information that must be maintained, or on processes that occur over the course of performing the tasks.     

The importance of working memory updating in the Prisoner’s dilemma

Successful cooperation requires that humans can flexibly adjust choices to their partner’s behaviour. This, in turn, presupposes a representation of a partner’s past decisions in working memory. The aim of the current study was to investigate the role of working memory processes in cooperation. For that purpose, we tested the effects of working memory updating (Experiment 1) and working memory maintenance demands (Experiments 2 and 3) on cooperative behaviour in the Prisoner’s dilemma game. We found that demands on updating, but not maintenance, of working memory contents impaired strategy use in the Prisoner’s dilemma. Thus, our data show that updating a partner’s past behaviour in working memory represents an important precondition for strategy use in cooperation.     

Does maintaining bindings in visual working memory require more attention than maintaining features?

ABSTRACT

Whether more attention is required for maintaining bindings than maintaining features in visual working memory (VWM) remains an open question. If maintaining bindings in VWM does not require more attention than maintaining features, is it related to the stability of binding representations? In this study, we explored whether maintaining bindings requires more attention than maintaining features for similar and dissimilar objects by inserting a feature report task into the maintenance phase of VWM in Experiments 1 and 2. We also investigated whether the effect of similarity on the attentional requirement for maintaining bindings and features is due to the stability of VWM representations by inserting a suffix during the maintenance phase of VWM in Experiment 3. The results showed that when object-based attention was consumed, bindings were more impaired than features for dissimilar objects but not for similar objects. We also found that the bindings of similar objects were less interfered by the suffix than those of dissimilar objects. Our findings suggest that maintaining bindings does not require more attention than maintaining features when the binding representations are stable in VWM and similarity improves the stability of binding representations.     

Do gains in working memory capacity explain the written self-disclosure effect?

Klein and Boals (2001) concluded that expressive writing about negative life events improves health by reducing intrusive thoughts, as measured by the Impact of Events Scale (IES), and thus freeing working memory (WM) capacity. We replicated their WM gain and rejected the possibility that it reflected task practice alone. We extended their work by showing that such WM effects and reductions in self-reported health symptoms can be observed within a short time frame of a week in a normal population of college students and can occur without reductions in IES scores. Two alternative explanations are discussed of how WM gains can be observed in the written self-disclosure effect without reductions in the frequency of intrusive thoughts and avoidance attempts.     

Children’s higher order cognitive abilities and the development of secondary memory

The relations between higher cognitive abilities and immediate and delayed recall were studied in 57 children (6–16 years of age). The participants were tested repeatedly on free recall of a supraspan list (Children’s Memory Scale), and their fluid ability was also assessed (Woodcock—Johnson III Spatial Relations). Consistent with Unsworth and Engle’s (2007) account of the relation between memory and higher order cognition, the children’s fluid ability was significantly correlated with retrieval from secondary memory, regardless of whether it was measured using immediate or delayed recall. Multiple regression analyses provided further support for this view, revealing that measures of immediate and delayed retrieval from secondary memory accounted for the same variance in the children’s fluid ability.     

Being a good witness: The roles of benevolence and working memory capacity in rapport’s effect on eyewitness memory

Prior studies suggest that building rapport with eyewitnesses can produce measurable recall improvements, but the underlying mechanisms of rapport’s possible effects on recall remain underexplored. The present study investigated two possible mechanisms for rapport’s impact: (1) improved working memory capacity and (2) increased benevolence. Participants (N = 105) viewed a mock theft video, followed by one of two possible pre-interview interactions: rapport-building or a control interaction. Next, participants completed measures of working memory, altruism, and benevolence (pre-interview and post-interview), before recalling details of the theft. Analyses revealed that, when controlling for the effects of the interaction duration and participants’ pre- and post-interview benevolence, rapport did not affect eyewitness recall directly. However, rapport building did increase benevolence measured after and associated with the substantive eyewitness interview, which in turn predicted more accurate and new details reported, and fewer subjective/other details reported. These findings support benevolence toward the interviewer as a mechanism behind rapport’s effect on eyewitness recall. Implications for investigative interviews in relation to benevolence and motivating reciprocation are discussed.     

Individual and age-related differences in children’s working memory

The purpose of this study was to investigate the degree to which age-related and individual differences in children’s working memory (WM) are due to a general or task-specific capacity system. Experiment 1 correlated children’s (N=146; age range 5–19 years) verbal and visual-spatial working memory performance with various intelligence and achievement measures. The results supporting a general system were that (1) visual-spatial and verbal WM measures were significantly intercorrelated with and without age partialed out and (2) both verbal and visual-spatial WM measures were significantly correlated with diverse achievement and intelligence measures. Experiment 2 compared three age groups (N=192; 7-, 10-, and 13-year-olds) on working-memory performance tasks under initial, enhanced (cued), and maintenance conditions. The results supporting a general capacity system were that (1) age-related performance differences in WM were found on all conditions and not isolated to specific processes, (2) the maintenance measures (high-load condition) predicted the variance better in age-related performance than process measures, and (3) although individual differences in WM performance reflected two independent operations, these operations produced similar correlations to achievement within age groups. Overall, the results support a general capacity explanation of age-related and individual differences in children’s WM performance.     

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.     

Can we model organismic causes of working memory,efficiency and fluid intelligence? A meta-subjective perspective

I critically examine the target paper by Demetriou et al. (2013) noticing that their epistemological perspective is meta-empiricist (i.e., taking the viewpoint of an external observer). This viewpoint is contrasted with to a metasubjective perspective (i.e., that of the subject-matter itself — organismic processes). I explain working memory (whose key developmental determinant is mental – M – attention), as well as processing speed, and Gf from a metasubjective perspective; and I emphasize that difficulty of an item/task is relative to the trade-off level between its item/task mental–attentional demand and the participant's mental–attentional capacity. I list principles of measurement for proper assessment of mental/executive/endogenous attention (M-capacity) and explain some of the results of Demetriou et al. as resulting from inadequate control of this M-demand/M-capacity trade off in their tasks. Demetriou et al. have achieved clear demonstration that WM, Gf, and processing speed are distinct latent variables whose inter-relations change with age. To clarify further their organismic causal determinants they should make a “metasubjective turn” in their theorizing.     

How semantic organisation influences primary school children’s working memory

The present study focuses on the semantic organisation of material in working memory. We developed a new measure in which students memorised unrelated words from lists. In our study, we manipulated the association between words in the lists. The material was organised so as to elicit a semantic organisation (categorical and thematic). The task was then administered to a group of 6–10-year-old children. The semantic organisation of the material prompted a better recall, which depended on the type of semantic organisation. In the same vein, the number of intrusion errors was influenced by the semantic links between words and was higher when words in the list were associated categorically. These results seemed to depend partly on the participants’ age, being evident only in the younger children.     

Richard Lynn’s contributions to personality and intelligence

An evaluation is presented of Lynn’s work on national differences in personality, race differences in intelligence, national IQs & economic development, correlates of national IQs, the Flynn effect, sex differences, eugenics and dysgenics, race differences in psychopathic personality, and intelligence of the Jews.     

Lapsed attention to elapsed time? Individual differences in working memory capacity and temporal reproduction

Working memory capacity (WMC) predicts individual differences in a wide range of mental abilities. In three experiments we examined whether WMC would predict temporal judgment. Low-WMC temporal reproductions were consistently too long for the shortest duration and too short for the longest, but were accurate (unbiased) for the intermediate. In contrast, high-WMC temporal reproductions were more accurate (unbiased) across the range. Thus low-WMC showed a classic “migration effect” (Vierordt's Law) to a greater extent than high-WMC. Furthermore reproduction errors depended more on temporal context than the absolute durations of “shortest,” “longest,” and “intermediate.” Low-WMC reproductions were overall more variable than high-WMC. General fluid intelligence (gF) was also related to temporal bias and variability. However, WMC-related timing differences were only attenuated and not eliminated with gF as covariate. Results are discussed in terms of attention, memory, and other psychological constructs.     

What limits working memory capacity? Evidence for modality-specific sources to the simultaneous storage of visual and auditory arrays

There is considerable debate on whether working memory (WM) storage is mediated by distinct subsystems for auditory and visual stimuli (Baddeley, 1986) or whether it is constrained by a single, central capacity-limited system (Cowan, 2006). Recent studies have addressed this issue by measuring the dual-task cost during the concurrent storage of auditory and visual arrays (e.g., Cocchini, Logie, Della Sala, MacPherson, & Baddeley, 2002; Fougnie & Marois, 2006; Saults & Cowan, 2007). However, studies have yielded widely different dual-task costs, which have been taken to support both modality-specific and central capacity-limit accounts of WM storage. Here, we demonstrate that the controversies regarding such costs mostly stem from how these costs are measured. Measures that compare combined dual-task capacity with the higher single-task capacity support a single, central WM store when there is a large disparity between the single-task capacities (Experiment 1) but not when the single-task capacities are well equated (Experiment 2). In contrast, measures of the dual-task cost that normalize for differences in single-task capacity reveal evidence for modality-specific stores, regardless of single-task performance. Moreover, these normalized measures indicate that dual-task cost is much smaller if the tasks do not involve maintaining bound feature representations in WM (Experiment 3). Taken together, these experiments not only resolve a discrepancy in the field and clarify how to assess the dual-task cost but also indicate that WM capacity can be constrained both by modality-specific and modality-independent sources of information processing.     

Decomposing the relationship between cognitive functioning and self-referent memory beliefs in older adulthood: what’s memory got to do with it?

With advancing age, episodic memory performance shows marked declines along with concurrent reports of lower subjective memory beliefs. Given that normative age-related declines in episodic memory co-occur with declines in other cognitive domains, we examined the relationship between memory beliefs and multiple domains of cognitive functioning. Confirmatory bi-factor structural equation models were used to parse the shared and independent variance among factors representing episodic memory, psychomotor speed, and executive reasoning in one large cohort study (Senior Odyssey, N = 462), and replicated using another large cohort of healthy older adults (ACTIVE, N = 2802). Accounting for a general fluid cognitive functioning factor (comprised of the shared variance among measures of episodic memory, speed, and reasoning) attenuated the relationship between objective memory performance and subjective memory beliefs in both samples. Moreover, the general cognitive functioning factor was the strongest predictor of memory beliefs in both samples. These findings are consistent with the notion that dispositional memory beliefs may reflect perceptions of cognition more broadly. This may be one reason why memory beliefs have broad predictive validity for interventions that target fluid cognitive ability.     

There is more than one level in color naming — A reply to Zollinger (1984)

Summary It is argued that the structure of the Munsell solid is not sufficient to explain the evolution of color terms as Zollinger (1984) has argued. A manifold model of color perception is described with a local metric structure of discriminability and a global categorical structure. This model elucidates the interdependency of the different levels of constraints on color naming and permits the integration of experimental results which cannot be explained in the model underlying Zollinger's (1984) color-metric argument for the emergence of turquoise.     

Models of verbal working memory capacity: what does it take to make them work?

Theories of working memory (WM) capacity limits will be more useful when we know what aspects of performance are governed by the limits and what aspects are governed by other memory mechanisms. Whereas considerable progress has been made on models of WM capacity limits for visual arrays of separate objects, less progress has been made in understanding verbal materials, especially when words are mentally combined to form multiword units or chunks. Toward a more comprehensive theory of capacity limits, we examined models of forced-choice recognition of words within printed lists, using materials designed to produce multiword chunks in memory (e.g., leather brief case). Several simple models were tested against data from a variety of list lengths and potential chunk sizes, with test conditions that only imperfectly elicited the interword associations. According to the most successful model, participants retained about 3 chunks on average in a capacity-limited region of WM, with some chunks being only subsets of the presented associative information (e.g., leather brief case retained with leather as one chunk and brief case as another). The addition to the model of an activated long-term memory component unlimited in capacity was needed. A fixed-capacity limit appears critical to account for immediate verbal recognition and other forms of WM. We advance a model-based approach that allows capacity to be assessed despite other important processing contributions. Starting with a psychological-process model of WM capacity developed to understand visual arrays, we arrive at a more unified and complete model.     

The impact of working memory training on near and far transfer measures: Is it all about fluid intelligence?

This randomized control study investigates the effects of working memory (WM) training on near (similar WM memory tasks) and far (math problem-solving processes and accuracy tasks) transfer in children aged 7 to 11 years who vary in fluid intelligence. Participants were randomly assigned to either a control group or one of two WM training conditions (repeated practice vs. cued recall). ?When compared to the control condition, the results show that the cued recall condition yields higher post-test scores for the far transfer measures, whereas the repeated practice condition yields higher scores for the near transfer? measures. However, these finding are qualified by significant treatment × fluid intelligence interactions. Thus, improvements in WM and related measures, as well as the positive transfer in learning outcomes, are moderated by fluid intelligence.     

What’s the object of object working memory in infancy? Unraveling ‘what’ and ‘how many’

Infants have a bandwidth-limited object working memory (WM) that can both individuate and identify objects in a scene, (answering ‘how many?’ or ‘what?’, respectively). Studies of infants’ WM for objects have typically looked for limits on either ‘how many’ or ‘what’, yielding different estimates of infant capacity. Infants can keep track of about three individuals (regardless of identity), but appear to be much more limited in the number of specific identities they can recall. Why are the limits on ‘how many’ and ‘what’ different? Are the limits entirely separate, do they interact, or are they simply two different aspects of the same underlying limit?We sought to unravel these limits in a series of experiments which tested 9- and 12-month-olds’ WM for object identities under varying degrees of difficulty. In a violation-of-expectation looking-time task, we hid objects one at a time behind separate screens, and then probed infants’ WM for the shape identity of the penultimate object in the sequence. We manipulated the difficulty of the task by varying both the number of objects in hiding locations and the number of means by which infants could detect a shape change to the probed object. We found that 9-month-olds’ WM for identities was limited by the number of hiding locations: when the probed object was one of two objects hidden (one in each of two locations), 9-month-olds succeeded, and they did so even though they were given only one means to detect the change. However, when the probed object was one of three objects hidden (one in each of three locations), they failed, even when they were given two means to detect the shape change. Twelve-month-olds, by contrast, succeeded at the most difficult task level.Results show that WM for ‘how many’ and for ‘what’ are not entirely separate. Individuated objects are tracked relatively cheaply. Maintaining bindings between indexed objects and identifying featural information incurs a greater attentional/memory cost. This cost reduces with development. We conclude that infant WM supports a small number of featureless object representations that index the current locations of objects. These can have featural information bound to them, but only at substantial cost.     

Wanting more than you have and it’s Consequences for Well-being

Americans have a lot of stuff, but are not necessarily happier for it. One possibility is that even if we want what we have, we want more. Wanting more may increase have-want discrepancies and reduce well-being. In this paper, we introduce the construct wanting more, and show that it negatively predicts well-being. We then identify materialism as a mediator of this relationship. Wanting more negatively effects well-being at least in part because those who want more are more likely to be materialistic. Finally, we show that wanting more than one has and wanting what one has are distinct constructs, and that wanting what one has moderates the relationship between wanting more and well-being. Those who want more are less happy only if they also do not want what they have. Wanting what one has may reduce attention to have-want discrepancies that result from wanting more.