Background: Delay aversion, the motivation to escape or avoid delay, results in preference for small immediate over large delayed rewards. Delay aversion has been proposed as one distinctive psychological process that may underlie the behavioural symptoms and cognitive deficits of attention deficit/ hyperactivity disorder (ADHD). Furthermore, the delay aversion hypothesis predicts that ADHD children's preference for immediate small over large delayed rewards will be reduced when stimulation, which makes time appear to pass more quickly, is added to the delay interval. The current paper tests these predictions. Methods: A group of children with a diagnosis of ADHD (with or without oppositional defiant disorder (ODD)), a group with a diagnosis of high-functioning autism (HFA), and a normal control group were compared on an experimental paradigm giving repeated choices between small immediate and large delayed rewards (Maudsley Index of Delay Aversion-MIDA) under two conditions (stimulation and no stimulation). Results: As predicted, ADHD children displayed a stronger preference than the HFA and control children for the small immediate rewards under the no-stimulation condition. The ADHD children preferences were normalised under the stimulation condition with no differences between the groups. This pattern of results was the same whether the ADHD children had comorbid ODD or not. Discussion: The findings from the MIDA are consistent with the delay aversion hypothesis of ADHD in showing that preference for small immediate rewards over large delayed rewards is a specific feature of ADHD and that this preference can be reduced by the addition of stimulation. Further research is required to better understand the emotional and motivational mechanisms underpinning delay aversion.

Thirty hyperactive and 30 non-hyperactive children were confronted with a delay, consisting of a waiting situation of 15 minutes, either with or without extra stimulation provided by the presentation of a videotape. The behaviour of the child during the waiting period was videotaped and later coded by two naive observers. In line with theories that emphasise the stimulation-seeking function of hyperactive behaviours, such as the optimal stimulation account and the delay aversion theory, a group by stimulation effect was hypothesised. For two categories of activity this was found, with ADHD children displaying more activity than non-ADHD children in the no-stimulation but not in the stimulation condition. These data provide support for the stimulation-seeking function of certain features of ADHD hyperactivity.

The state regulation hypothesis postulates that poor task performance of children with ADHD is related to poor energetical state control. The current study aimed to investigate whether such a deficit persists in adult ADHD. Event-related potentials (ERPs) were recorded during administration of a Go/No-Go task that incorporated the stressor presentation rate of stimuli. It was found that males with ADHD responded slower than control males in the slow condition, which was accompanied by smaller parietal P3s, suggesting less effort allocation. No group differences were found with respect to the response inhibition measures (errors of commission and the N2 effect). In conclusion, problems in state regulation seem to persist in male adults with ADHD.

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and (iv) rhythmicity in neuroendocrine and neurophysiological responsiveness. On this basis, we propose a neurobiological framework to guide future study, which sees circadian effects in ADHD, along with other aspects of ADHD arousal-related deficits (e.g., cognitive energetic deficits), as being the result of dysregulated locus coeruleus function. Based on this perspective specific recommendations for future research are presented.