This post isn't about indexes... Have you guys noticed that the coding subtest score is consistently very low in ASD test takers? I scored 7 on coding and 14 on symbol search iirc. Reading these IQ threads over the last years the most consistent thing I see is low coding score. If anyone was bored enough to look through the IQ threads on WP I think they would find the coding scores almost 1SD below the population mean.
Anyway here is an interesting read for you guys. I'll paste a piece of it and the link. It's a long read but it's pretty interesting.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3093048/
Quote:
The Wechsler intelligence scales (Wechsler, 1974; 1981; 1991) have had widespread application in the assessment of children and adults with autism. Aside from the traditional role of these procedures in educational, vocational, and clinical diagnostic applications, they have been used in autism research to separate high functioning from low functioning autism, for differential diagnostic purposes within the autism spectrum and, perhaps most significantly, for delineating the pattern of cognitive function in autism. The Wechsler contains 11 or more subtests depending upon the version used, making it possible to obtain a cognitive profile of diverse abilities in addition to the Verbal, Performance, and Full Scale IQ scores. A profile apparently unique to high functioning autism has been identified in numerous studies, characterized by relatively high scores on the Block Design subtest and relatively low scores on Comprehension (Rumsey, 1992; Siegel, Minshew & Goldstein, 1996; Yirmiya & Sigman, 1991). In fact, in a review of 14 studies reporting Wechsler IQ subtest scores in autism conducted since 1965, Siegel et al. (1996) observed that all fourteen reported the Block Design subtest to be the highest Performance subtest, while Comprehension was the lowest Verbal subtest in thirteen of the studies. The consistency of these findings across studies is quite remarkable, given the differences in data analytic and research design methodologies across studies and sites, as well as the various versions of the Wechsler scales used. The Block Design subtest was of particular interest because, often enough, it was not only normal but in the superior range, suggesting the presence of an exceptional spatial constructional ability in some individuals with high functioning autism.
In addition to the subtest profile and IQ scores, the Wechsler scales have been repeatedly factor analyzed in both normal and clinical populations. Exploratory factor analysis has generally demonstrated that when the 11 subtest versions of these scales are studied, a three-factor solution is consistently found. The factors are called Verbal Comprehension (VC), Perceptual Organization (PO) and Attention/Concentration or Freedom from Distractibility (FFD). The VC factor receives high loadings from Information, Comprehension, Similarities, and Vocabulary subtests. The PO factor receives high loadings from Picture Completion, Picture Arrangement, Block Design, and Object Assembly subtests. The Digit Span, Arithmetic and, at times, Digit Symbol or Coding subtests, constitute the FFD factor.
More recent applications of factor analysis have employed confirmatory approaches, made possible by advances in structural equation modeling (Jorskog, 1979). Confirmatory factor analysis (CFA) is designed to evaluate specific hypotheses about the number of factors that make up a particular test battery and the pattern of factor loadings. Thompson, in his text on these two methods (2004), indicates that most investigators now find CFA more useful than exploratory approaches, particularly if they have specific expectations about the factor structure of the test. CFA studies of both the WISC-R and WAIS-R in normal and clinical samples have typically confirmed the three-factor model described here. More recently, the addition of several subtests to the WAIS-III and WISC-III allowed for testing of four- and five-factor models. The addition of these subtests made a four-factor solution more optimal than the previously reported three-factor model. In this four-factor solution, the VC, PO and FFD factors are retained. However, an additional subtest, Letter-Number Sequencing, is added to the FFD factor, which is renamed Working Memory (WM). Also, the Digit Symbol subtest is paired with the Symbol Search subtest to form a Processing Speed factor (PS). Thus, even for these newer versions of the Wechsler scales, the three-factor model identified in their predecessors continues to provide a meaningful organization of the major subtests of the Wechsler scales.
For autism, the factor structure of the Wechsler scales is of clinical interest because it has been shown that using the same tests, the factor structure, or loading pattern, may differ in different clinical groups so that there may be a group that does not show the pattern of VC, PO, and FFD factors found on the Wechsler scales produced by normally developing individuals. The implication of different loading patterns is that the organization of cognitive abilities may differ among these groups. Such an occurrence would bespeak a different organization of cognitive processing or intelligence from what is found in normal individuals. And in fact, in a study done some time ago with a small sample (n = 33), it was found that individuals with autism had a different factor structure on the Wechsler scales from normal controls suggesting the possibility of a “social intelligence” factor (Lincoln, Courchesne, Kilman, Elmasian, & Allen, 1988). Using principal components the investigators identified three factors in their autism sample. The first was the traditional verbal factor, but the second factor only received high loadings from Block Design, Object Assembly and Digit Symbol/Coding. The third factor only received high loadings from Picture Arrangement and Picture Completion. Thus, while the small sample size precluded any definitive conclusions, the findings were suggestive of a dissociation between performance tests that the authors described as nonverbal, social, and context-relevant and performance tests that do not involve these abilities but assess visual analysis and integration. Lincoln et al. did not specifically characterize this third factor as a “social intelligence” factor, but rather described the pattern found in high functioning autism as a mismatch between verbal reasoning and context recognition with more well developed perceptual-motor organization abilities. They also suggested that factors may be representative of various aspects of brain function. We would suggest that the identification of such a dissociation may underlie a deficit in social intelligence in autism, but since the Wechsler scales assess cognitive processes and not social functioning the identification of a “social intelligence” factor using CFA is primarily of interest because of the insights it may provide relating to social cognition. Relevant aspects of such cognition would be appreciation of context and inference making.
The unusual subtest profile of those with high functioning autism is also suggestive of a factor structure that would substantially vary from that identified in normal populations. In autism, on the Verbal Comprehension Tests the Comprehension subtest is typically substantially lower than Information, Vocabulary and Similarities. On the Perceptual Organization subtests, Block Design is substantially higher than Picture Completion and Picture Arrangement. Digit Symbol may also be depressed. These profile differences would suggest that when a factor analysis is performed, while three or four factors may be extracted they will have different loading patterns from the national normative samples, and goodness-of-fit may not be as adequate as is found in the standardization samples.
In the current study we investigate these possibilities using CFA to evaluate a number of a priori models in children and adults with high functioning autism, and in the national samples. Using the traditional 11 subtest version of the Wechsler scales we tested the traditional one, two and three factor models, as well as two different four factor models based on profiles commonly associated with autism as reviewed in Siegel, Minshew and Goldstein (1996). The general hypothesis was that the autism groups would demonstrate a different factor structure than was found for the Wechsler scale national standardization samples.
20 Dec 2010, 11:37 pm
) on the last
You and I haven't been posting much lately. I have hardly posted at all in General Autism Discussion since October.
) to meet folks of the opposite sex for the things that those of the opposite sex often do when they get together 
