This study investigated the Wechsler Performance IQ (PIQ) or Perceptual Reasoning Index (PRI)/ Perceptual Organization Index (POI) change over time and its relation to ability levels. PIQ or PRI/ POI was analyzed because of the known sensitivity of nonverbal scales to the Flynn effect. Scores were analyzed using two methods. First, analysis of…

Results for 3,340 participants taking a battery of cognitive tests and an analysis of the Spanish standardization of the Wechsler Adult Intelligence Scale-III support the differentiation of intelligence across the range of ability, with WAIS-III results more supportive of the differentiation theory. (SLD)

Examined the assumption that Spearman's law acts unsystematically and approximately uniformly for various subtests of cognitive ability in an IQ test battery when high- and low-ability IQ groups are selected. Data from national standardization samples for Wechsler adult and child IQ tests affirm regularities in Spearman's "Law of Diminishing…

The validity of a technique for estimating premorbid intellectual functioning based on Wechsler Adult Intelligence Scale-Revised (WAIS-R) subtest performance and demographic information used in best-performance fashion was investigated with the 1,880 individuals from the WAIS-R standardization sample. Results support use of the approach. (SLD)

Results from a representative sample of 123 adults in the United Kingdom tested with the Wechsler Adult Intelligence Scale-Revised and a test of word identification time are in line with previous findings that speed of information processing is significantly related to performance IQ but not to verbal IQ. (SLD)