The Perceptual Organization Index is part of the Performance Scale of the Wechsler cognitive assessment measures, the Wechsler Intelligence Scale for Children, 3rd edition (WISC-III, 1991), and the Wechsler Adult Intelligent Scale, 3rd edition (WAIS-III, 1997). The POI measures visual-spatial organization and visual-motor skills within a time limit. For the WISC-III, the subtests Picture Completion, Picture Concepts, Block Design, and Object Assembly load onto the POI. For the WAIS-III, the subtests Picture Completion, Block Design, and Matrix Reasoning load onto the POI.
The WISC-III and WAIS-III are older versions of the Wechsler cognitive assessment measures, and have since been replaced by the WISC-IV (2003) and WAIS-IV (2008). For both the WISC-IV and the WAIS-IV, the Perceptual Organization Index has been renamed the Perceptual Reasoning Index (PRI). The PRI measures fluid reasoning (use of sequential, inductive, and deductive reasoning) and visual processing (the ability to synthesize and process visual stimuli). Unlike the POI, scores on the PRI are less influenced by speed and the ability to work quickly.
Research has shown that performance on the Block Design task, which loads onto the POI for both the WISC-III and the WAIS-III, is often an area of strength for children with ASD.