More to ADHD than meets the eye: Observable abnormalities in search behaviour do not account for performance deficits on a discrimination task

Abstract

Children with Attention Deficit/Hyperactivity Disorder (ADHD) often perform poorly on tasks requiring sustained and systematic attention to stimuli for extended periods of time. The current paper tested the hypothesis that such deficits are the result of observable abnormalities in search behaviour (e.g., attention-onset, -duration and -sequencing), and therefore can be explained without reference to deficits in non-observable (i.e., cognitive) processes. Forty boys (20 ADHD and 20 controls) performed a computer-based complex discrimination task adapted from the Matching Familiar Figures Task with four different fixed search interval lengths (5-, 10-, 15-and 20-s). Children with ADHD identified fewer targets than controls (p < 0.001), initiated searches later, spent less time attending to stimuli, and searched in a less intensive and less systematic way (p's < 0.05). There were significant univariate associations between ADHD, task performance and search behaviour. However, there was no support for the hypothesis that abnormalities in search carried the effect of ADHD on performance. The pattern of results in fact suggested that abnormal attending during testing is a statistical marker, rather than a mediator, of ADHD performance deficits. The results confirm the importance of examining covert processes, as well as behavioural abnormalities when trying to understand the psychopathophyiology of ADHD.Attention Deficit/Hyperactivity Disorder (ADHD; [1]) is a disorder of childhood and adolescence characterised by a pattern of extreme, pervasive, persistent and debilitating inattention, overactivity and impulsiveness. Children with ADHD are more likely than their peers to experience educational under-achievement, social isolation and antisocial behaviour during the school years and to go on to have significant difficulties in the post-school years. Children with ADHD often perform poorly on tasks requiring the sustained and systematic allocation of attention over periods of extended time [2]. This appears to be true of tasks that require vigilance for rare targets amongst consecutively presented distractors (e.g., Continuous Performance Task; ). It is also true of more complex tasks that require self-directed and controlled search for targets amongst multiple concurrently presented distractors (e.g., Matching Familiar Figures Task; [4]).In trying to explain the causes of this commonly observed pattern of performance deficit a range of different mechanisms operating at different levels of analysis have been invoked. For instance, cognitive accounts link deficits in performance to impairments in covert processes such as information encoding and retrieval as well as the 'holding

The impact of instruction and response cost on the modulation of response-style in children with ADHD

“…The number of errors, in contrast, did not decrease substantially in the Accuracy1 task compared to Baseline in either group, which was unexpected. Similar effects have been described by the Delay Aversion Theory for children with ADHD who do not improve in accuracy when more time is available [13]. In the present case, however, this effect was observed in both groups.…”

“…Another major theory that departed from studies of the MFFT is the Delay Aversion Theory, which claims that behavioural problems of children with ADHD reflect attempts to avoid or escape delay [ 10 - 13 ]. In a self-paced visual search task, the amount of time which a participant will spend on the visual search and the degree of certitude he needs in order to respond are matters of deliberate choice and depend on individual standards.…”

“…to executive function (see [ 22 ]). Visual search abnormalities in ADHD, on the other hand, seem to be strategic rather than cognitive in nature [ 13 , 23 ]: children with ADHD initiate search later, spend less time on the search, and use less systematic scanning strategies. Studies with normal individuals have related atypical speed-accuracy trade-offs in the MFFT to deficiencies in monitoring and metacognitive control [ 24 , 25 ].…”

Adrenoleukodystrophy with Frontal Lobe Involvement and Attention Deficit Hyperactivity Disorder-like Symptoms

“…Recent imaging studies revealed that dysfunction of the front-striatal neuronal networks were associated with ADHD. It is speculated that frontal lobes, caudate nucleus, thalamus, nucleus accumbens, and cerebellum are responsible for both inattention and hyperactivity/impulsivity [11]. It is noteworthy that our variant ALD case had initial involvement of the fronto-striatal neuronal networks, and cerebellum similar to the responsible lesions for ADHD.…”

DRD4 and&nbsp;DAT1 in ADHD: Functional neurobiology to pharmacogenetics

“…ADHD can persist into adulthood, and increases the risk for antisocial personality disorder,4 later criminality,5 as well as drug and alcohol misuse 6. Pharmacologic, neurobiologic, and genetic studies support the notion that ADHD has a neurodevelopmental basis with strong genetic and nongenetic components,7 implicating neurotransmission dysregulation within brain circuits underpinning cognition and motivation 8. Disruption of multiple neurotransmitter systems has been proposed.…”