Memory for Action Rules and Reaction Time Variability in Attention-Deficit/Hyperactivity Disorder

Area of Science:

• Cognitive Neuroscience
• Neurodevelopmental Disorders

Background:

• Attention-deficit/hyperactivity disorder (ADHD) is characterized by heightened reaction time (RT) variability.
• This variability is a core phenotype, often attributed to attention lapses.

Purpose of the Study:

• To investigate the specific roles of perceptual processing and working memory (WM) in RT variability in ADHD.
• To differentiate between attention deficits and WM retrieval deficits as causes of RT variability.

Main Methods:

• Manipulated working memory (WM) load in choice reaction time (RT) tasks for college students with and without ADHD.
• Applied Ex-Gaussian distribution fitting and evidence accumulation modeling to analyze RT data.

Main Results:

• Individuals with ADHD exhibited a higher frequency of exceptionally slow RTs across all conditions.
• The most significant group differences in RT variability emerged under high WM load conditions.
• RT variability in ADHD was not linked to perceptual deficits but to a reduced rate of WM retrieval.

Conclusions:

• Increased RT variability in ADHD is primarily associated with difficulties in retrieving action rules from working memory.
• Findings suggest that WM retrieval deficits, rather than attention lapses, are a key factor in ADHD-related RT variability.