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Test of two views of impulsivity in hyperactive and conduct-disordered children
1Department of Psychology, The Chinese University of Hong Kong, Shatin, New Territories.
Insights
Hyperactive children, not those with conduct disorder, show impulsivity by failing to withhold responses. This output inhibition deficit is specific to hyperactive children, impacting their motor control.
Area of Science:
- Child Psychology
- Neurodevelopmental Disorders
- Behavioral Science
Background:
- Impulsivity is a key feature in hyperactive and conduct-disordered children.
- Understanding the specific nature of impulsivity is crucial for targeted interventions.
Purpose of the Study:
- To investigate the nature of impulsivity in hyperactive (HA) and conduct-disordered (CD) children.
- To differentiate impulsivity deficits at perceptual versus motor stages.
Main Methods:
- Two experiments were conducted using priming and delayed reaction time tasks.
- Four groups of 7-8 year olds were studied: pure hyperactive (HA), hyperactive/conduct-disordered (HA+CD), pure conduct-disordered (CD), and normal controls (N).
- Participants had normal IQs.
Main Results:
- No group showed perceptual impulsivity under simple, organized conditions.
- Hyperactive (HA) children exhibited disinhibition at the motor output stage, failing to withhold responses.
- This motor output deficit was specific to HA children, not seen in CD or HA+CD groups.
Conclusions:
- Impulsivity in hyperactive children is characterized by a specific deficit in motor response inhibition.
- This finding differentiates hyperactive children from those with conduct disorder regarding impulsivity expression.
- Results suggest distinct neurocognitive profiles for hyperactivity and conduct disorder.
Abstract:
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.