Visuospatial Processing Bias in ADHD: A Potential Artifact in the Wechsler Adult Intelligence Scale and the Rorschach Inkblots Test

Global processing bias is the automatic tendency to process the global picture before processing the local details. Recent studies suggest that individuals with attention-deficit/hyperactivity disorder (ADHD) show a lack of global processing bias. In the current study, we examined whether lack of global processing bias affects performance on 2 psychological tests, Wechsler Adult Intelligence Scale IV (WAIS-IV) and the Rorschach inkblots test, which require the use of visuospatial processing while measuring different psychological constructs. Adult participants (30 ADHD and 30 typically developing controls) completed the subtests of the WAIS-IV, which rely on visuospatial components, and the Rorschach inkblots test. We found no indication of differences in general fluid intelligence between the groups. On the WAIS-IV test, ADHD participants consistently exhibited superior performance on tasks that relied on local processing and inferior performance on tasks that relied on global processing when compared with healthy controls. On the Rorschach inkblots test, ADHD participants exhibited more responses that referred to local aspects (part/s) of the stimulus and fewer responses that referred to global aspects (whole) of the stimulus. These findings imply that when patients with ADHD are given psychological tests that require visuospatial processing, a potential confound of visuospatial processing style needs to be considered. Public Significance Statement Individuals with attention-deficit/hyperactivity disorder show increased visuospatial processing of details and reduced processing of the global picture. This unique visuospatial processing style affects performance on psychological tests, such as the Wechsler intelligence quotient test and the Rorschach test and thus indicates a potential confound of visuospatial processing style.