Inhibition and working memory in young preschool children with symptoms of ADHD and/or oppositional-defiant disorder

Background: Early symptoms of attention deficit/hyperactivity disorder (ADHD) and oppositional-defiant disorder (ODD) are associated with deficits in cognitive self-regulatory processes or executive functions (EF)s. However, the hypothesis that neurocognitive deficits underlying the two disorders are already evident during early preschool years still has limited empirical support. The present study investigated associations between symptoms of ADHD and/or ODD and two core EFs, inhibition and working memory, in a large nonclinical sample of 3-year old children. Method: Participants were 1045 children (554 boys, age 37–47 months), recruited from the population based Norwegian Mother and Child Cohort Study (MoBa). Relations between behavioral symptoms and measures of inhibition and working memory were studied both categorically and dimensionally. Results: Children with co-occurring symptoms of ADHD and ODD performed at a significantly lower level than typically developing children in 4 out of 5 EF measures. Symptoms of ADHD, both alone and in combination with ODD, were associated with reduced performance on tests of inhibition in the group comparisons. Dimensional analyses showed that performance within both EF domains contributed to variance primarily in ADHD symptom load. The associations between test results and behavioral symptoms remained significant after gender and verbal skills had been controlled. Conclusion: Young preschoolers show the same pattern of relations between EF and behavioral symptoms of ADHD and/or ODD as previously described in older children diagnosed with ADHD and/or ODD. Effect sizes were generally small, indicating that measures of EF have limited clinical utility at this stage in development.     

Time keeping and working memory development in early adolescence: A 4-year follow-up

In this longitudinal study, we examined time keeping in relation to working memory (WM) development. School-aged children completed two tasks of WM updating and a time monitoring task in which they indicated the passing of time every 5 min while watching a film. Children completed these tasks first when they were 8 to 12 years old and then 4 years later when they were 12 to 16 years old. Time keeping in early adolescence showed a different pattern of outcome measures than 4 years earlier, with reduced clock checking and increased timing error. However, relative changes in WM development moderated these adverse effects. Adolescents with greater relative gains in WM development were better calibrated than participants with less developing WM functions. We discuss these findings in relation to individual and developmental differences in executive control functions and socioemotionally driven reward seeking.     

Working memory updating and the development of rule-guided behavior

The transition from middle childhood into adolescence is marked by both increasing independence and also extensive change in the daily requirements of familial demands, social pressures, and academic achievement. To manage this increased complexity, children must develop the ability to use abstract rules that guide the choice of behavior across a range of circumstances. Here, we tested children through adults in a task that requires increasing levels of rule abstraction, while separately manipulating competition among alternatives in working memory. We found that age-related differences in rule-guided behavior can be explained in terms of improvement in rule abstraction, which we suggest involves a working memory updating mechanism. Furthermore, family socioeconomic status (SES) predicted change in rule-guided behavior, such that higher SES predicted better performance with development. We discuss these results within a working memory gating framework for abstract rule-guided behavior.     

Variation in verbal fluency: A latent variable analysis of clustering,switching, and overall performance

Verbal fluency tasks have long been used to assess and estimate group and individual differences in executive functioning in both cognitive and neuropsychological research domains. Despite their ubiquity, however, the specific component processes important for success in these tasks have remained elusive. The current work sought to reveal these various components and their respective roles in determining performance in fluency tasks using latent variable analysis. Two types of verbal fluency (semantic and letter) were compared along with several cognitive constructs of interest (working memory capacity, inhibition, vocabulary size, and processing speed) in order to determine which constructs are necessary for performance in these tasks. The results are discussed within the context of a two-stage cyclical search process in which participants first search for higher order categories and then search for specific items within these categories.     

The development of and interaction among alerting,orienting, and executive attention in children

A sex-balanced sample (N = 96) of children from age 6.5 to age 12.5 completed a modified Attention Network Test. Across these ages, we found evidence for developmental changes to alerting and executive control but stable orienting. Additionally, we found that the youngest members of our sample manifested an interaction between alerting and executive control that is opposite to that typically found in adults; a reversal that diminishes with age to achieve the adult pattern by the older end of the age range of our sample.     

Examining methodological variation in response inhibition: The effects of outcome measures and task characteristics on age-related differences

This study addressed methodological issues common to developmental studies on response inhibition. Age-related differences were investigated using two Stroop-like tasks with different levels of complexity and comparing different outcome measures in a sample of 340 children and adolescents aged 7–15 years. First, speed and accuracy of task performance were examined; the results showing that improvement in speed continued until age 13 in both the basic naming task and the two inhibition tasks. Improvement in accuracy was less consistent and continued until age 9 or 13 years. Second, two different algorithms were employed to control for the effects of basic processes in inhibition tasks. The difference algorithm indicated age-related differences similar to those for speed. The ratio algorithm, however, suggested earlier deceleration of development of response inhibition at 9 or 11 years of age. Factors related to the cognitive requirements and presented stimuli also had an effect on the results. The present findings shed light on the inconsistencies in the developmental studies of response inhibition and demonstrated that the selection of outcome measures and task characteristics are critical because they affect the way development is depicted.     

Correlation of motor skill,mental rotation,and working memory in 3- to 6-year-old children

A relationship between motor processes and mental rotation has been suggested by current research; however, the influence of working memory on this relationship has not yet been determined. Therefore, a correlation between motor tests, paper–pencil and chronometric mental rotation tests, and working memory tests were conducted in 3- to 6-year-old children. A stepwise multiple-regression showed that 55.5% of the variance was explained by the working memory tests: digit span forward and Corsi forward. This indicates that working memory and executive functions may play an important role in mental rotation and motor processes.     

Adolescent coping with everyday stressors: A seven-nation study of youth from central,eastern, southern,and northern Europe

The present study compares problem-specific coping strategies and coping styles of European adolescents from seven nations. The sample consisted of 3031 adolescent participants, aged 11 to 20, from Croatia, the Czech Republic, Germany, Italy, Norway, Portugal, and Switzerland. The adolescents completed the Coping Across Situations Questionnaire (CASQ) by indicating which coping strategies (from 20 alternatives) they usually employed in dealing with age-specific problems (covering 8 different domains). The strategies can be collapsed to three coping styles: active coping, internal coping, and withdrawal. Results show that adolescents from all seven nations predominantly employed functional forms of coping, i.e., active coping and internal coping. In addition, the pattern of frequently and rarely applied coping strategies was similar across cultures. Differences in coping style were revealed for some, but not all problem domains, suggesting that cross-cultural similarity in coping exists for specific stressors. Problem-specific analyses helped to clarify where cultural influence is most distinct. Whereas cultural diversity was highest for coping with job-related problems, coping with self- and future-related problems was highly similar among adolescents from all the nations. Despite the considerable traditional, educational, and economic differences among the cultures investigated, the similarities in coping behaviour were impressive. Explanations for cultural universals and differences in adolescent coping are discussed.     

School enrolment and executive functioning: A longitudinal perspective on developmental changes,the influence of learning context,and the prediction of pre-academic skills

The present two-year longitudinal study addressed developmental changes in different aspects of executive functioning (i.e., inhibition, updating, and cognitive flexibility) in a sample of 264 children aged between 5 and 7 years. Of special interest were issues of developmental progression over time, the influence of learning context and the predictive power of executive functions and school context for emerging academic skills. The results revealed pronounced improvements in all executive measures, both over time and as a function of age. For the learning context, small and age-dependent effects on executive skills were found. Inhibition uniquely contributed to the prediction of aspects of emerging academic skills, over and above chronological age and language skills.     

Children's verbal working memory: relative importance of storage, general processing speed, and domain-general controlled attention

This study evaluated multiple constraints of verbal working memory in typically developing 7- to 11-year-olds. Multiple measures of verbal working memory and the predictors-short-term memory storage, general speed, and domain-general controlled attention were used. General linear modeling (GLM) showed that storage and the efficiency of controlled attention (i.e., speed of updating information during attention switching) contributed to significant variance in children's verbal working memory. In a secondary analysis verbal storage and domain-general attention (focus switching accuracy and speed of updating on switch) emerged as significant predictors. Results suggest domain-general attention and verbal storage mechanisms to be independent constraints of verbal working memory.     

A structural equation modeling of executive functions,IQ and mathematical skills in primary students: Differential effects on number production,mental calculus and arithmetical problems

Though the relationship between executive functions (EFs) and mathematical skills has been well documented, little is known about how both EFs and IQ differentially support diverse math domains in primary students. Inconsistency of results may be due to the statistical techniques employed, specifically, if the analysis is conducted with observed variables, i.e., regression analysis, or at the latent level, i.e., structural equation modeling (SEM). The current study explores the contribution of both EFs and IQ in mathematics through an SEM approach. A total of 118 8- to 12-year-olds were administered measures of EFs, crystallized (Gc) and fluid (Gf) intelligence, and math abilities (i.e., number production, mental calculus and arithmetical problem-solving). Confirmatory factor analysis (CFA) offered support for the three-factor solution of EFs: (1) working memory (WM), (2) shifting, and (3) inhibition. Regarding the relationship among EFs, IQ and math abilities, the results of the SEM analysis showed that (i) WM and age predict number production and mental calculus, and (ii) shifting and sex predict arithmetical problem-solving. In all of the SEM models, EFs partially or totally mediated the relationship between IQ, age and math achievement. These results suggest that EFs differentially supports math abilities in primary-school children and is a more significant predictor of math achievement than IQ level.     

A computational model of frontal lobe dysfunction: working memory and the Tower of Hanoi task

A symbolic computer model, employing the perceptual strategy, is presented for solving Tower of Hanoi problems. The model is calibrated—in terms of the number of problems solved, time taken, and number of moves made—to the performance of 20 normal subjects. It is then "lesioned" by increasing the decay rate of elements in working memory to model the performance of 20 patients with lesions to the prefrontal cortex. The model captures both the main effects of subject groups (patients and normal controls) performance, and the subject groups (patients and normal controls) by problem difficulty interactions. This leads us to support the working memory hypothesis of frontal lobe functions, but for a narrow range of problems.     

Variation in working memory capacity,fluid intelligence,and episodic recall: A latent variable examination of differences in the dynamics of free recall

A latent variable analysis was conducted to examine the nature of individual differences in the dynamics of free recall and cognitive abilities. Participants performed multiple measures of free recall, working memory capacity (WMC), and fluid intelligence (gF). For each free recall task, recall accuracy, recall latency, and number of intrusion errors were determined, and latent factors were derived for each. It was found that recall accuracy was negatively related to both recall latency and number of intrusions, and recall latency and number of intrusions were positively related. Furthermore, latent WMC and gF factors were positively related to recall accuracy, but negatively related to recall latency and number of intrusions. Finally, a cluster analysis revealed that subgroups of participants with deficits in focusing the search had deficits in recovering degraded representations or deficits in monitoring the products of retrieval. The results are consistent with the idea that variation in the dynamics of free recall, WMC, and gF are primarily due to differences in search set size, but differences in recovery and monitoring are also important.     

Applying a dual process model of self-regulation: The association between executive working memory capacity,negative urgency,and negative mood induction on pre-potent response inhibition

This study tested a dual-process model of self-control where the combination of high impulsivity (negative urgency – NU), weak reflective/control processes (low executive working memory capacity – E-WMC), and a cognitive load is associated with increased failures to inhibit pre-potent responses on a cued go/no-go task. Using a within-subjects design, a cognitive load with and without negative emotional load was implemented to consider situational factors. Results suggested that: (1) high NU was associated with low E-WMC; (2) low E-WMC significantly predicted more inhibitory control failures across tasks; and (3) there was a significant interaction of E-WMC and NU, revealing those with low E-WMC and high NU had the highest rates of inhibitory control failures on all conditions of the task. In conclusion, results suggest that while E-WMC is a strong independent predictor of inhibitory control, NU provides additional information for vulnerability to problems associated with self-regulation.