Journal of the International Neuropsychological Society

Research Articles

Inhibitory control and psychopathology: A meta-analysis of studies using the stop signal task


a1 Department of Psychiatry, Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada

a2 Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada


The Stop Signal Task (SST) is a measure that has been used widely to assess response inhibition. We conducted a meta-analysis of studies that examined SST performance in patients with various psychiatric disorders to determine the magnitude and generality of deficient inhibition. A five-item instrument was used to assess the methodological quality of studies. We found medium deficits in stop signal reaction time (SSRT), reflecting the speed of the inhibitory process, for attention-deficit hyperactivity disorder (ADHD) (g = 0.62), obsessive compulsive disorder (OCD) (g = 0.77) and schizophrenia (SCZ) (g = 0.69). SSRT was less impaired or normal for anxiety disorder (ANX), autism, major depressive disorder (MDD), oppositional defiant disorder/conduct disorder (ODD/CD), pathological gambling, reading disability (RD), substance dependence, and Tourette syndrome. We observed a large SSRT deficit for comorbid ADHD + RD (g = 0.82). SSRT was less than moderately impaired for ADHD + ANX and ADHD + ODD/CD. Study quality did not significantly affect SSRT across ADHD studies. This confirms an inhibition deficit in ADHD, and suggests that comorbid ADHD has different effects on inhibition in patients with ANX, ODD/CD, and RD. Further studies are needed to firmly establish an inhibition deficit in OCD and SCZ. (JINS, 2010, 16, 1064–1076.)

(Received March 08 2010)

(Reviewed July 14 2010)

(Accepted July 14 2010)


c1 Correspondence and reprint requests to: Russell Schachar, Toronto Dominion Bank Financial Group Chair in Child and Adolescent Psychiatry, Neurosciences and Mental Health Program, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada, M5G 1X8. E-mail: