Systematic Review: Attention-Deficit/Hyperactivity Disorder and Instrumental Learning

Area of Science:

• Neuroscience
• Developmental Psychology
• Child Psychiatry

Background:

• Instrumental learning deficits are hypothesized to contribute to attention-deficit/hyperactivity disorder (ADHD).
• A comprehensive systematic review on instrumental learning in ADHD was lacking.
• This review aimed to synthesize existing research on instrumental learning in children with ADHD compared to typically developing (TD) peers.

Purpose of the Study:

• To examine differences in basic instrumental learning between children with ADHD and TD children.
• To investigate the impact of reinforcement characteristics (form, magnitude, schedule, complexity) on instrumental learning in ADHD.
• To assess the effects of medication on instrumental learning in children with ADHD.

Main Methods:

• A systematic literature search was conducted across multiple databases (PubMed, PsyINFO, CINAHL, EMBASE, ERIC, Web of Science) up to March 2020.
• Included were experimental studies comparing instrumental learning in ADHD vs. TD groups or examining reinforcement/medication effects within ADHD samples.
• Study quality was assessed using adapted Hombrados and Waddington criteria to evaluate risk of bias.

Main Results:

• No significant differences in basic instrumental learning or effects of reinforcement form/magnitude were found between ADHD and TD children.
• Findings for reinforcement schedule and reversal learning were mixed.
• Children with ADHD demonstrated deficits in conditional discrimination learning compared to TD children, and methylphenidate improved instrumental learning.
• The included studies were of generally poor quality, with small sample sizes and inconsistent reporting.

Conclusions:

• No clear instrumental learning deficits were identified in children with ADHD under controlled laboratory conditions.
• Deficits are apparent in more complex learning tasks, specifically conditional discrimination.
• Further research with standardized methodologies is required to clarify instrumental learning in ADHD.