Age-related differences in reaction time task performance in young children

Performance of reaction time (RT) tasks was investigated in young children and adults to test the hypothesis that age-related differences in processing speed supersede a “global” mechanism and are a function of specific differences in task demands and processing requirements. The sample consisted of 54 4-year-olds, 53 5-year-olds, 59 6-year-olds, and 35 adults from Russia. Using the regression approach pioneered by Brinley and the transformation method proposed by Madden and colleagues and Ridderinkhoff and van der Molen, age-related differences in processing speed differed among RT tasks with varying demands. In particular, RTs differed between children and adults on tasks that required response suppression, discrimination of color or spatial orientation, reversal of contingencies of previously learned stimulus–response rules, and greater stimulus–response complexity. Relative costs of these RT task differences were larger than predicted by the global difference hypothesis except for response suppression. Among young children, age-related differences larger than predicted by the global difference hypothesis were evident when tasks required color or spatial orientation discrimination and stimulus–response rule complexity, but not for response suppression or reversal of stimulus–response contingencies. Process-specific, age-related differences in processing speed that support heterochronicity of brain development during childhood were revealed

The temporal dynamic of response inhibition in early childhood: An ERP study of partial and successful inhibition

Event-related potentials were recorded while five-year-old children completed a Go/No-Go task that distinguished between partial inhibition (i.e., response is initiated but cancelled before completion) and successful inhibition (i.e., response is inhibited before it is initiated). Partial inhibition trials were characterized by faster response initiation and later latency of the lateral frontal negativity (LFN) than successful Go and successful inhibition trials. The speed of response initiation was influenced by the response speed on previous trials and influenced the response speed on subsequent trials. Response initiation and action decision dynamically influenced each other, and their temporal interplay determined response inhibition success

Contribution of reactive and proactive control to children's working memory performance:Insight from item recall durations in response sequence planning

The present study addressed whether developmental improvement in working memory span task performance relies upon a growing ability to proactively plan response sequences during childhood. Two hundred thirteen children completed a working memory span task in which they used a touchscreen to reproduce orally presented sequences of animal names. Children were assessed longitudinally at 7 time points between 3 and 10 years of age. Twenty-one young adults also completed the same task. Proactive response sequence planning was assessed by comparing recall durations for the 1st item (preparatory interval) and subsequent items. At preschool age, the preparatory interval was generally shorter than subsequent item recall durations, whereas it was systematically longer during elementary school and in adults. Although children mostly approached the task reactively at preschool, they proactively planned response sequences with increasing efficiency from age 7 on, like adults. These findings clarify the nature of the changes in executive control that support working memory performance with age

Viewing Preschool Disruptive Behavior Disorders and ADHD Through A Developmental Lens: What We Know & What We Need to Know

There is now little doubt that DSM-IV behavior disorders are present and identifiable during the preschool years (1,2). With only minor modifications to DSM-IV Disruptive Behavior Disorders (DBDs) and attention-deficit/hyperactivity disorder (ADHD) nosology, multiple, independent studies have shown similar prevalence rates and correlates as in older children (1). In the preschool age range, these disorders also have modest stability (3-6). It is clear that the behaviors that comprise DBDs and ADHD (e.g., noncompliance, rule-breaking, aggression, destruction of property, hyperactivity, inattention, and impulsivity) impair children’s functioning and that caregivers of young children often experience considerable difficulty in managing those who exhibit high levels of these behaviors. Increasingly, preschoolers are being referred to mental health clinics for DBDS and ADHD (7), with escalating rates of pharmacological treatments (8). Thus, the “real world” consequences of behavior disorders are substantial for young children and their families and often mark the onset of long-term developmental maladaptation that marks psychopathology (9). Concerted effort to characterize the clinical manifestations of these disorders in early childhood more precisely will maximize our ability to intervene effectively in the lives of young children affected with DBDs and ADHD and, ultimately to reduce their long-term health burden. The increasing consensus that these syndromes exist in young children also comes with growing concern that these disorders may be developmentally misspecified, particularly for young children who are not at the extremes (10). In this paper, we review the extant empirical evidence through a “developmental lens,” with an eye to analyzing how the absence of a developmental approach may hinder accurate identification. Further, we show how integrating evidence from developmental science provides useful guideposts for generating and testing a developmentally-specified nosology. Together with the plethora of work on preschool psychopathology over the past decade, this provides a strong foundation for charting a course for the next generation of more refined efforts in early childhood

Changing the rules at the drop of a hat: An ERP study of preschoolers\u27 set-shifting ability

We examined the neural correlates of set-shifting in 5-year-old children and examined whether the ease of switching was affected by varying the number of non-switch trials preceding a switch

Changing the rules at the drop of a hat: An ERP study of preschoolers\u27 set-shifting ability

We examined the neural correlates of set-shifting in 5-year-old children and examined whether the ease of switching was affected by varying the number of non-switch trials preceding a switch

Executive function deficits in preschool children with ADHD and DBD

Background: Impairments in executive functions (EF) are consistently associated with attention deficit hyperactivity disorder (ADHD) and to a lesser extent, with disruptive behavior disorder (DBD), that is, oppositional defiant disorder or conduct disorder, in school-aged children. Recently, larger numbers of children with these disorders are diagnosed earlier in development, yet knowledge about impairments in clinically diagnosed preschool children and the role of comorbidity is limited. Therefore, the aim of the current study was to examine EF in clinically referred preschool children with a clinical diagnosis of ADHD, DBD and ADHD + DBD. Method: Participants were 202 children aged 3.5–5.5 years, 61 with ADHD only, 33 with DBD only, 52 with comorbid ADHD + DBD and 56 typically developing children. Five EF tasks were administered. Results: Confirmatory factor analysis showed that the two-factor model (inhibition and working memory) fit the data better than a one-factor model in this clinical sample. Preschoolers with ADHD displayed inhibition deficits, also after controlling for IQ. Likewise, preschoolers with DBD displayed impaired inhibition, but when IQ was controlled differences were carried mostly by the effect on the task where motivational demands were high (i.e. when tangible rewards were used). This pattern was also found in the interaction between ADHD and DBD; impaired inhibition in the comorbid group, however, was more severe than in the DBD group. Regarding working memory, few group differences were found. Conclusions: Clinically diagnosed preschool children with ADHD showed robust inhibition deficits, whereas preschool children with DBD showed impaired inhibition especially where motivational incentives were prominent. Severity of inhibition impairment in the comorbid group was similar to the ADHD group

Executive function deficits in preschool children with ADHD and DBD

Background: Impairments in executive functions (EF) are consistently associated with attention deficit hyperactivity disorder (ADHD) and to a lesser extent, with disruptive behavior disorder (DBD), that is, oppositional defiant disorder or conduct disorder, in school-aged children. Recently, larger numbers of children with these disorders are diagnosed earlier in development, yet knowledge about impairments in clinically diagnosed preschool children and the role of comorbidity is limited. Therefore, the aim of the current study was to examine EF in clinically referred preschool children with a clinical diagnosis of ADHD, DBD and ADHD + DBD. Method: Participants were 202 children aged 3.5–5.5 years, 61 with ADHD only, 33 with DBD only, 52 with comorbid ADHD + DBD and 56 typically developing children. Five EF tasks were administered. Results: Confirmatory factor analysis showed that the two-factor model (inhibition and working memory) fit the data better than a one-factor model in this clinical sample. Preschoolers with ADHD displayed inhibition deficits, also after controlling for IQ. Likewise, preschoolers with DBD displayed impaired inhibition, but when IQ was controlled differences were carried mostly by the effect on the task where motivational demands were high (i.e. when tangible rewards were used). This pattern was also found in the interaction between ADHD and DBD; impaired inhibition in the comorbid group, however, was more severe than in the DBD group. Regarding working memory, few group differences were found. Conclusions: Clinically diagnosed preschool children with ADHD showed robust inhibition deficits, whereas preschool children with DBD showed impaired inhibition especially where motivational incentives were prominent. Severity of inhibition impairment in the comorbid group was similar to the ADHD group