The purpose of this study is to examine the WAIS-III General Ability Index (GAI) in a sample of 33 neuropsychiatry inpatients and 47 forensic psychiatry inpatients. The GAI is comprised of the six subtests that form the Verbal Comprehension and the Perceptual Organization Indexes. The GAI, although highly correlated with the FSIQ, was on average 5.3 points higher in the neuropsychiatry sample and 4.2 points higher in the forensic psychiatry sample. The GAI was significantly higher than the Working Memory and the Processing Speed Indexes in both groups. The GAI, a composite measure of verbal and nonverbal intellect, appears to be an appropriate measure for use in day-to-day clinical practice in neuropsychology. To facilitate clinical use, statistically reliable difference scores between the GAI and the WMI and PSI, for the 95% confidence interval, are presented.

Author notes

Portions of these data were presented at the National Academy of Neuropsychology Annual Conference, Miami, FL, October 2002 and the European Conference on Psychological Assessment, Malaga, Spain, April 2004.