Interference control in adult ADHD: No evidence for interference control deficits if response speed is controlled by delta plots

• We examined whether ADHD patients suffer of interference control deficits.
• We compared the Stroop effect between patients and controls by delta plots.
• Delta plots allow controlling for response speed differences between two groups.
• No interference control deficits were found when response speed was controlled.
• We conclude that ADHD patients show no interference control deficits.

Several theoretical accounts assume that interference control deficits belong to the core symptoms of adult ADHD. However, findings of increased interference effects in adult ADHD patients compared with healthy adults may be confounded with the simultaneous finding of generally slower responses in the patient group. The current study compared the magnitude of the interference effect in the Stroop task between a group of adults with ADHD and a healthy adult control group in a procedure that accounted for differences in overall response speed by using delta plots. The amount of interference did not differ between patient and control group at comparable reaction time levels. These results challenge the conclusions of the previous studies, in that they indicate that interference control is not impaired in adult ADHD.