Objective: Deficits in the ability to perceive time have been proposed as an etiologic mechanism in the development of the cognitive and behavioral characteristics associated with ADHD. However, previous studies testing the presence of timing deficits have produced idiosyncratic results. This is in large part due to the underutilization of insights from basic timing research, and from the inherent difficulty that arises when a single index of performance (i.e., reaction time [RT] or accuracy) is used to index the health of what is essentially a multiple-component process. The current article utilizes a diffusion model approach to isolate the component processes involved in timing (i.e., internal clock speed, decision-making speed, speed/accuracy trade-off strategies, and nondecision time) using a well-validated timing task. Method: Fifty children with ADHD and 32 non-ADHD controls aged 8-12 completed a temporal bisection procedure. Results: Diffusion model parameters indicated that both the internal clock and decisionmaking speeds were slower among children with ADHD. However, the strength of evidence for slowed decision making far outweighed evidence for a slower internal clock. Conclusions: Slower evidence accumulation during decision making is domain-general deficit in ADHD. Such slowing is consistent with adaptive-gain theories, which posit that a suboptimal ratio of neural signal-to-noise is characteristic of children with ADHD.
All Science Journal Classification (ASJC) codes
- Neuropsychology and Physiological Psychology