title: Using the Diffusion Model to Explain Cognitive Deficits in Attention Deficit Hyperactivity Disorder.
abstract: Slow, variable, and error-prone performance on speeded reaction time (RT) tasks has been well documented in childhood ADHD, but equally well documented is the context-dependent nature of those deficits, particularly with respect to event rate. As event rates increase (or, as the interstimulus intervals become shorter), RTs decrease, a pattern of performance that has long been interpreted as evidence that cognitive deficits in ADHD are a downstream consequence of a fundamental difficulty in the regulation of arousal to meet task demands. We test the extent to which this is a misinterpretation of the data that occurs when RT and accuracy are considered separately, as is common in neurocognitive research. In two samples of children aged 8-10 with (N = 97; 33 girls) and without (N = 39; 26 girls) ADHD, we used the diffusion model, an influential computational model of RT, to examine the effect of event rate on inhibitory control in a go-no-go task. Contrary to longstanding belief, we found that fast event rates slowed the rate at which children with ADHD accumulated evidence to make a decision to "no-go", as indexed by drift rate. This in turn resulted in a higher proportion of failed inhibits, and occurred despite increased task engagement, as reflected by changes in the starting point of the decision process. Thus, although faster event rates increased task engagement among children with ADHD, the increased engagement was unable to counteract the concurrent slowing of processing speed to "no-go" decisions. Implications for theoretical models of ADHD and treatments are discussed.
authors.affiliation: Department of Psychology, The Pennsylvania State University, Moore Building, University Park, PA, 16802, USA. CLH39@psu.edu.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Huang-Pollock
authors.affiliation: The Department of Psychology, Ohio State University, 291 Psychology Building, Columbus, OH, 43210, USA.
authors.forename: Roger
authors.initials: R
authors.lastname: Ratcliff
authors.affiliation: The Department of Psychology, Ohio State University, 291 Psychology Building, Columbus, OH, 43210, USA.
authors.forename: Gail
authors.initials: G
authors.lastname: McKoon
authors.affiliation: Department of Psychology, The Pennsylvania State University, Moore Building, University Park, PA, 16802, USA.
authors.forename: Zvi
authors.initials: Z
authors.lastname: Shapiro
authors.affiliation: Department of Psychology, The Pennsylvania State University, Moore Building, University Park, PA, 16802, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Weigard
authors.affiliation: Department of Psychology, The Pennsylvania State University, Moore Building, University Park, PA, 16802, USA.
authors.forename: Hilary
authors.initials: H
authors.lastname: Galloway-Long
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000150:complications / Q000503:physiopathology*; D002648:Child; D060825:Cognitive Dysfunction / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008960:Models, Psychological; D011930:Reaction Time / Q000502:physiology*
keywords: ADHD; Arousal; Diffusion model; Drift rate; Event rate; Inhibition