Cognitive styles in adolescents previously diagnosed as hyperactive

The North American Perspective On Attention Deficit Hyperactivity Disorder

The purpose of the present paper is to (1) provide an overview of the nature of attention-deficit hyperactivity disorder (ADHD) as it seems to be viewed by North American clinicians and clinical scientists; (2) describe its diagnostic criteria as they are applied in that region; (3) discuss the prevalence of ADHD in the region; and (4) briefly present a new theoretical model of the authors emerging from that North American perspective. Some of the critical issues related to these matters will be raised along the way. Given the thousands of scientific papers on this topic, however, an overview of these various topics is all that space here can afford. Readers wishing a more thorough treatment of these topics as well as those pertaining to history, developmental courses, associated risks, assessment, and treatments for ADHD are directed to other writings by the author (Barkley, 1990).

Performance on Embedded Figures Tests

We examined individual performance on an embedded figures test, in two separate studies. Performance measures were both the number (m) of hits (H) and the number of false alarms (FA), and their respective reaction times (RT). Using these measures, we postulated four templates of performance, indicative of field dependence (mH = low, RTH = long, mFA = high), field independence (mH = high, RTH = short, mFA = low), impulsiveness (mH = low, RTH = short, mFA = high), and reflectiveness (mH = high, RTH = long, mFA = low). In the first study, individual profiles were correlated with these four templates, whose mean values were updated in a stepwise manner, under the constraint that the individual profile had to be substantially correlated with the emerging template (r > 0.9). This procedure resulted in the final placement of a total of 64 individuals (80%) into one of the four templates. In the second study, we could identify 87% of the participants in such a manner. These participants also provided us with performance data on the rod-and-frame test (RFT), and a line-bisection task (whose analysis here is innovative), as well as scores on the sensation-seeking scales. We emphasize the utility of adopting such a finely-tuned approach to the study of the disembedding aspect of the cognitive style, and to the profiling of individual differences in general.

Separable/integral classification by hyperactive and normal children

This research tested the hypothesis that information-processing deficits associated with hyperactivity implicate a self-regulatory dysfunction. Hyperactive and control children were compared on nonspeeded classification tasks. In Studies 1 and 2, children classified sets of either three (triads) or four (tetrads) stimuli. The stimuli varied simultaneously on size and brightness or on length and density. They could be classified analytically (separably) on the basis of identical values for one dimension and holistically (integrally) on the basis of overall similarity. Control children made an equal number of dimensional classifications for triads and for tetrads. As predicted, however, hyperactive children made fewer dimensional classifications for tetrads, suggesting that they apparently resorted to less effortful holistic responding under the increased processing load. In an unexpected finding in Study 1, older hyperactive children appeared to behave like younger controls, making more dimensional classifications when size, rather than brightness, was the shared dimension. Study 3 explored the possibility that hyperactive children lagged behind the controls in their responding to the shared dimensions. Three age groups of normal children (mean ages: 5, 8, and 11 years) and adults were asked to classify stimuli that varied on size and brightness. Consistent with the lag hypothesis, normal preschoolers behaved like the young hyperactive children in Study 1, classifying equally on the basis of size and brightness. The discussion focuses on the contribution of processing load and stimulus salience to the cognitive deficits of hyperactive children.

The Stroop revisited: a meta-analysis of interference control in AD/HD

BACKGROUND

An inhibition deficit, including poor interference control, has been implicated as one of the core deficits in AD/HD. Interference control is clinically measured by the Stroop Colour-Word Task. The aim of this meta-analysis was to investigate the strength of an interference deficit in AD/HD as measured by the Stroop Colour-Word Task and to assess the role of moderating variables that could explain the results. These moderating variables included: methods of calculating the interference score, comorbid reading and psychiatric disorders, AD/HD-subtypes, gender, age, intellectual functioning, medication, and sample size.

METHODS

Seventeen independent studies were located including 1395 children, adolescents, and young adults, in the age range of 6-27 years. A meta-analysis was conducted to assess the effect sizes for the scores on the word and the colour card as well as the interference score.

RESULTS

Children with AD/HD performed more poorly on all three dependent variables. The effect sizes for word reading (d=.49) and colour naming (d=.58) were larger and more homogeneous than the effect size for the interference score (d=.35). The method used to calculate the interference score strongly influenced the findings for this measure. When interference control was calculated as the difference between the score on the colour card minus the score on the colour-word card, no differences were found between AD/HD groups and normal control groups.

DISCUSSION

The Stroop Colour-Word Task, in standard form, does not provide strong evidence for a deficit in interference control in AD/HD. However, the Stroop Colour-Word Task may not be a valid measure of interference control in AD/HD and alternative methodologies may be needed to test this aspect of the inhibitory deficit model in AD/HD.

Executive function profile of children with attention deficit hyperactivity disorder

We explored the neuropsychological profile for executive functions of children with attention deficit hyperactivity disorder (ADHD) to assess whether problems associated with the two most cited relevant processes--inhibition and attentional problems--were the core of any executive function difficulty. A battery of executive function tests was administered to 31 children with a clinical diagnosis of ADHD and to 33 normal control participants, all aged between 7 and 12. The executive function battery encompassed a number of tasks, selected because each had multiple measures: a sustained attention reaction time task, a related vigilance task, an adaptation of the Hayling Sentence Completion Test, an adaptation of the Brixton Spatial Rule Attainment Test, a Letter Fluency task, a number Stroop task, and an "n-back" working memory task. The overall pattern of the results fit well with those obtained in previous studies as far as abnormalities of the ADHD group in the domain of inhibitory processes, attentional functions, and executive functions. The children with ADHD, although performing well on baseline tasks, performed more poorly than the controls on all the experimental tasks with one borderline exception: Letter Fluency, where the children with ADHD showed a very different pattern than most adult frontal lobe subgroups. However, there was no specific impairment on measures of inhibitory processes. In addition, strategy generation and use were severely affected in the ADHD group. Particular findings fitted well with disorders of a high-level effort system and of a monitoring system.

Biological contributions to the presentation and understanding of attention-deficit/hyperactivity disorder: a review

Attention-deficit/hyperactivity disorder (ADHD) is the most commonly diagnosed disorder in children today with estimated prevalence rates falling between 3 and 5% of children (American Psychiatric Association, 1994). From inception, research has focused on studying varying facets of this disorder with initial efforts primarily focusing on treatment outcome. However, prominent efforts have been made in recent research efforts to shed light on the etiology of this disorder. Such research has discovered the contribution of genetic inheritance, as well as environmental factors that lead to the development of this disorder. Furthermore, studies using neurological and neuropsychological assessment measures have implicated the involvement of various Parts of the brain. This article critically reviews this body of research in light of its impact on the current specific neuropsychologically based etiological theories, as well as the most beneficial directions for future research.

Synchronization, anticipation, and consistency in motor timing of children with dimensionally defined attention deficit hyperactivity behaviour

We tested the hypothesis that children with hyperactive behaviour are impaired in the temporal organization of their motor output. The performance of 11 boys, scoring above a cut-off on standard scales of overactivity and inattention, was compared to that of controls in progressively more complex Motor-timing tasks. The tasks administered required self-paced and externally paced Sensorimotor Synchronization and Sensorimotor Anticipation. Deficits at a perceptual level were investigated with a Time-discrimination task. As hypothesized, we found that hyperactive children had no deficits in their perception of time but were impaired in timing their motor output. Hyperactive children were more inconsistent than controls in maintaining a freely chosen tapping rhythm, in synchronizing and in anticipating their motor response to external visual stimulation.

Inhibitory dysfunction in hyperactive boys

Recent evidence suggests that the main deficit in childhood hyperactivity is in frontal lobe-mediated self-regulative functions such as inhibitory control. Hyperactives have consistently been shown to perform poorly on the stop task, which is a laboratory measurement of inhibitory control. This study was aimed at extending knowledge about inhibitory processes involved in the hyperactive's performance on this task. For this purpose, the performance of 11 pervasive hyperactives was compared to the performance of normal children on two stop tasks which differed from each other in the contingency of timing of the stop signal. In Stop1 stop signals were internally related, i.e. presented at time intervals after onset of the response stimulus, whereas in Stop2 stop signals were externally related, i.e. presented at time intervals related to the subject's own go-process. Both tasks were modifications of the classical stop task in modality of the stop signal visual instead of auditory and in event rate, which was half-shortened. The aim of this study was: (a) to replicate the findings of deficient inhibitory functions in hyperactive children in the stop task in spite of modifications in modality and event rate; and (b) to elucidate (dis)similarities of stopping processes or of group differences in these stopping processes triggered by stop delays related either to external or to internal processes. Hyperactive children were less efficient than controls in inhibiting their motor response in both versions of the stop task. independent of whether the stop signals were externally or internally related. Furthermore, the go-process of the hyperactives was more variable and erratic in both tasks. Thus, the results strengthen the effectiveness of stop tasks in distinguishing hyperactive from normal children.

Test of two views of impulsivity in hyperactive and conduct-disordered children

The nature of impulsivity in hyperactive and conduct-disordered children was examined in two experiments, one involving a priming task, the other a delayed reaction time task. Four groups of children, aged 7 to 8 years and with IQs in the normal range, were recruited for study: (1) a pure hyperactive group (HA), (2) a hyperactive/conduct-disordered group (HA+CD), (3) a pure conduct-disordered group (CD), and (4) a normal control group (N). When the stimulus configuration and presentation were simple and well organized, none of the three clinical groups displayed any sign of impulsivity at the input/perceptual stage; there was no tendency to rush responding before adequate consideration of the relevant stimuli, i.e. a trading of accuracy for speed. Instead, the HA children were found to be disinhibited at the output/motor stage, i.e. failing to temporarily withhold activated responses. This deficit was found to be specific to the HA children; it was not observed in the CD and HA+CD children.

Distractibility in hyperactive and conduct-disordered children

Hyperactive children are often said to be inattentive and distractible. However, the results from a number of experimental studies are equivocal. To examine this discrepancy, a Chinese version of the Stroop Test was devised. Four groups of subjects recruited from a community sample of 1479 Chinese boys living in Hong Kong took part in the investigation. These were: (1) a pure hyperactive (HA) group; (2) a mixed hyperactive/conduct-disordered (HA + CD) group; (3) a pure conduct-disordered (CD) group; and (4) a normal (N) control group. The results revealed that HA children were more markedly affected by the introduction of distracting stimuli. This distractibility was probably a function of both stimulus potency and the random order in which stimuli were presented. The specificity of a greater distractibility to HA children indicates its diagnostic value with regard to hyperactivity. The failure to find a similar deficit in HA + CD children raises questions about the clinical identity of this mixed diagnostic group.

Executive functions and developmental psychopathology

In this paper, we consider the domain of executive functions (EFs) and their possible role in developmental psychopathologies. We first consider general theoretical and measurement issues involved in studying EFs and then review studies of EFs in four developmental psychopathologies: attention deficit hyperactivity disorder (ADHD), conduct disorder (CD), autism, and Tourette syndrome (TS). Our review reveals that EF deficits are consistently found in both ADHD and autism but not in CD (without ADHD) or in TS. Moreover, both the severity and profile of EF deficits appears to differ across ADHD and autism. Molar EF deficits are more severe in the latter than the former. In the few studies of more specific EF tasks, there are impairments in motor inhibition in ADHD but not in autism, whereas there are impairments in verbal working memory in autism but not ADHD. We close with a discussion of implications for future research.

The stability of dimensions of behavior in ADHD and normal children over an 8-year followup

The present study reports on standardized behavioral ratings received by a large sample of hyperactive children meeting research diagnostic criteria (n = 108) and a community control sample of normal children (n = 61) who were followed prospectively over 8 years into adolescence. On some parent-report measures both groups declined in the severity of their behavior problems across time, while on other measures only the hyperactive group declined, but the hyperactives always remained more deviant than the controls at followup. The hyperactives and controls also differed on most teacher and self-report ratings at followup. The greatest degree of agreement between raters at adolescence was between parent and youth ratings. These results are consistent with previous research demonstrating more deviant scores for hyperactive children than controls on various rating scales at adolescent followup. They also are consistent with research showing significant longitudinal continuity of both internalizing and externalizing behavioral pathology.

Frontal lobe functions in attention deficit disorder with and without hyperactivity: a review and research report

We review 22 neuropsychological studies of frontal lobe functions in children with attention deficit disorder with and without hyperactivity (ADD/+H, ADD/-H). Some measures presumed to assess frontal lobe dysfunctions were not reliably sensitive to the deficits occurring in either form of ADD. Tests of response inhibition more reliably distinguished ADD/+H from normal children. Where impairments were found on other tests between ADD and normal subjects, they were highly inconsistent across studies and seemed strongly related to age of the subjects and possibly to the version of the test employed. Other methodological differences across studies further contributed to the discrepant (LD) and conduct problems, with ADD may be an additional confounding factor in some, though not all, of these studies. In a separate reports. The co-morbidity of other disorders, such as learning disabilities (LD) and conduct problems, with ADD may be an additional confounding factor in some, though not all, of these studies. In a separate study, children with ADD/+H (n = 12) were then compared on frontal lobe tests to three other groups: ADD/-H (n = 12), LD but no ADD (n = 11), and normal children (n = 12) statistically covarying for differences in conduct problems across groups. Most measures did not distinguish among these groups. Both ADD groups made more omission errors on a Continuous Performance Test (CPT) than the normal group. All three clinical groups performed more poorly on the word and interference portions of the Stroop Test. Thus, while both types of ADD share some apparent similarities in deficits on a few frontal lobe tests in this study, the totality of existing findings suggests an additional problem with perceptual-motor speed and processing in the ADD/-H group.

Methylphenidate speeds evaluation processes of attention deficit disorder adolescents during a continuous performance test

Forty-six Attention Deficit Disorder (ADD) adolescents took a Continuous Performance Test (CPT) under placebo and methylphenidate (35.33 mg/day). The task required pressing one button for targets (p = .133), and another button for nontargets. Subjects displayed a strong bias to make the more frequent negative response before completely evaluating stimuli. Consistent with this assumption, subjects responded faster (by an average of 87 ms) to nontargets than to targets. Methylphenidate increased accuracy and speeded reaction times (RTs) to targets. The drug also increased the amplitude of the P3b component of the event-related potential for nontargets and shortened the latency of P3b for both targets and nontargets. These results suggest increased capacity allocation to and faster evaluation of task stimuli. Finally, the stimulant lengthened relative motor processing time (RT-P3b latency) for nontargets, a finding implying that response processing was accomplished with the benefit of earlier completion of evaluation processes for these stimuli.

Long-term outcome of hyperactive children: a review

Reports of adolescent outcome in attention deficit hyperactivity disorder have uniformly indicated high rates of behavioral problems including cognitive impairment. Dysfunction is markedly reduced in adulthood, but the pattern of outcome remains unchanged except for failure to document cognitive deficits. In adulthood, dysfunction is characterized by antisocial personality and substance (nonalcohol) use disorders. These are in turn associated with criminality. The little existing information on girls with attention deficit hyperactivity disorder does not suggest a worse outcome than for boys. Attempts to identify the children most likely to have a poor outcome have been largely unsuccessful.

What happens after a hyperactive child commits an error?

Children with a diagnosis of attention deficit disorder with hyperactivity can correct errors, just as controls can. They differ from controls in how they adjust the speed of processing on a trial after they have committed an error. Controls are fast in responding after an error when cognitive load is small. When cognitive load is high, however, they take considerable time to ensure, after an error has occurred, that a correct response is given. After an error has been committed, hyperactive children, irrespective of the demands of load, have no response adjustment and maintain a constant rate of processing.

Assessing and treating attention deficit disorder in adolescents. The clinical application of a single-case research design

Psychiatric assessment strategies that integrate research findings with daily practice are necessary and clinically useful. This paper uses the example of an attention deficit disordered adolescent to illustrate how double-blind placebo controlled and multi-dose adjustment designs can be successfully implemented in routine clinical practice. These designs are especially valuable in evaluating the therapeutic effect of methylphenidate because of biases that may lead to clinical misuse of this stimulant medication.

Attention and impulsivity characteristics of the biological and adoptive parents of hyperactive and normal control children

On tests comparing 176 biological and adoptive parents of hyperactive and normal control children, biological parents of hyperactives evidenced more attentional difficulties, slower mean reaction times, and fewer correct recognitions than did the other parents. They showed no significant differences in impulsivity. A familial association between childhood hyperactivity and attentional deficits in the biological parents was suggested, as was the persistence of attentional difficulties as compared to impulse control problems.

On resource strategy limitations in hyperactivity: cognitive impulsivity reconsidered

Overactive and distractible (hyperactives), normoactive and distractible, and normoactive and attentive (controls) children were administered a high-speed visual search task. The display load was manipulated and all subjects were administered the task in three instruction conditions: speed, 'normal' and accuracy. Speed-accuracy trade-off curves indicated that the controls and distractibles conformed to the fast guess model, which relates speed and accuracy. Hyperactives partially conformed to this model. It is concluded that a structural process deficit is not indicated by these data in hyperactivity. Rather, the evidence suggests that a resource strategy defect may be characteristic of hyperactivity.

The relationship of activity level ratings and cognitive impulsivity to task performance and academic achievement

The relationship of activity level ratings and cognitive impulsivity were analyzed in relation to performance of second-graders on several cognitive tasks and standardized achievement tests. Vocabulary was a strong and significant covariate on most dependent measures. In general, impulsivity-reflectivity had a far stronger effect on task performance and academic achievement than did activity level ratings, even when comparisons were made for groups with extremes of activity level ratings. The authors urge further research on the task approaches and compensatory strategies of children who are behaviorally hyperactive but cognitively reflective and academically successful.

Verbal mediation in high-active and cognitively impulsive second graders

Two problems associated with cognitive training programs using verbal mediation strategies are (a) noncomparability of samples and (b) the absence of base-line data documenting mediational deficiencies in target populations. The specific effects of high activity level (as assessed by a teacher's rating scale) and cognitive impulsivity (as assessed by the Matching Familiar Figures Test) on the production of relevant, task-directed verbalizations was examined in a group of 90 second graders. Impulsivity-reflectivity was found to be related to the production of both spontaneous and induced on-task verbalizations, but high activity level ratings were not.

Stimulant medications in adults with attention deficit disorder

The long-term prospective studies done in the last two decades on children suffering from attention deficit disorder with hyperactivity (ADD-H) give evidence of persistent disability in a majority of them when they reach adulthood. The literature on the use of stimulant medication in adults suffering from attention deficit disorder, residual type (ADD-R), is critically reviewed. After optimistic case reports two controlled double-blind studies have recently showed contradictory results. Some adults appear clearly to be helped by stimulant medication, but more investigations, especially with children diagnosed in childhood and followed-up, are needed before any firm conclusion can be made about the usefulness or non-usefulness of stimulants in ADD-R. There, as it is the case in childhood, medication might be insufficient by itself and might have to be associated with other forms of treatment.

Problem solving in hyperactive, normal, and reading-disabled boys

Diagnostic problem solving was examined in groups of hyperactive, normal, and nonhyperactive reading-disabled boys matched on age and verbal IQ. On the matrix solution task employed (a version of the game of 20 Questions) hyperactives used less efficient questions and strategies than the other two groups, in spite of the task being designed to maximize the performance of the hyperactives. Reading-disabled children were not significantly worse than normal children on the task. The results were interpreted as suggesting that the attentional difficulties of hyperactives retard the development of strategies for solving complex problems. Nonhyperactive reading-disabled children may be less affected in this area because of the absence of significant attentional difficulties.

Methylphenidate increases selectivity of visual scanning in children referred for hyperactivity

Visual scanning patterns were investigated in 32 children referred for symptoms of hyperactivity in a double-blind crossover comparison of methylphenidate and placebo treatments. Total errors, response latency, and visual fixations were recorded as the child scanned computer-generated visual matching-to-sample problems. Results indicated that the number of fixations on the standard stimulus in the matching task was significantly larger in the methylphenidate state. Drug treatment also resulted in a significant increase in the number of systematic comparisons between the standard and the variants in the task. However, the increased selectivity of attention to the standard stimulus was not accompanied by a reduction of total errors. It was suggested that the stimulant drug may increase attentional selectivity even when such a shift fails to produce improvement in task performance.

Cognitive styles and learning disabilities

Research is reviewed relating the cognitive style dimensions of field dependence and reflection-impulsivity to underachievement, process deficits (minimal brain dysfunction), and hyperactivity. In general, field independence and a reflective cognitive style are associated with better performance. The importance of modifying the learner's cognitive style and matching the learning environment to the learner's cognitive style also are examined.

The hyperactive child at adolescence: cognitive, emotional, and social functioning

In view of the paucity of detailed follow-up studies on hyperactive children, the performance of 15 adolescents diagnosed hyperactive 5 years previously was compared to that of a control group of equivalent age, sex, intelligence, and social class. Eleven cognitive tests measuring sustained attention, visual-motor and motor skills, abstraction, and reading ability, as well as three self-assessment tests examining self-esteem, activity level, social functioning, academic status, and career aspirations were administered. The hyperactives performed significantly worse than the controls on the sustained attention, visual-motor, and motor tasks, and on two of the four reading tests. They also gave themselves significantly lower ratings on some of the self-esteem and sociability items. It would appear that the hyperactives at adolescence still have attentional and stimulus-processing difficulties, which affect not only their academic performance but also their social functioning.