abstract: The Wechsler Intelligence Scale for Children – ; Fourth Edition (WISC – IV) is one of the most popular intelligence tests used for special education eligibility purposes in the United States. Despite the large prevalence of children and adolescents with Attention Deficit Hyperactivity Disorder (ADHD), the factor structure of the WISC – IV among this population has not been explored. Thus, the factor structure of WISC – IV scores among students with ADHD was investigated via replicatory factor analysis followed by a comparison with the factorial structure of the normative sample using the coefficient of congruence. The four factor model proposed by Wechsler was consistent with the factor structure found in the sample of students with ADHD for all subtests except Picture Concepts and Matrix Reasoning. The Verbal Comprehension and Processing Speed factors appeared to measure the same construct in the study sample as in the normative sample, while the Perceptual Reasoning and Working Memory factors were only fairly similar to the normative sample. It is recommended that clinicians interpret Perceptual Reasoning and Working Memory index scores of students with ADHD cautiously. Limitations of the study, future directions for research, and implications for practitioners are discussed. / Dissertation/Thesis / M.A. Educational Psychology 2011

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This study compares the role of cognitive processes in children diagnosed with learning disabilities (LD) through the traditional aptitude-achievement discrepancy model with students diagnosed on the basis of their low achievement alone. Historically, in North American settings, LD has been diagnosed when an individual’s achievement on standardized tests in reading, mathematics, or written expression is substantially lower than the expected level for age, schooling, and level of intelligence (American Psychiatric Association, 2000). As this conceptualization has come under increasing scrutiny, alternate identification methods such as the low achievement/non-discrepant method have been gaining support in the literature (e.g. Siegel, 1999; Stanovich, 2005). A secondary objective of this study is to determine whether identifiable differences exist between the cognitive profiles (WISC-IV) of students diagnosed with reading disability (RD) and mathematics disability (MD). This study also addresses whether the WISC-IV Working Memory Index can be used to differentiate between various categories of students with LD. The findings of this study indicate that the discrepant (DLD) and non-discrepant (NDLD) learning disability (LD) groups could not be distinguished by the WISC-IV Working Memory Index (WMI). Amongst the overall sample of students with LD, those with average or above working memory scores (high) could be differentiated from those with below average working memory scores (low) on the WISC-IV Perceptual Reasoning Index (PRI). Students with LD who had low WMI scores could also be differentiated from those with high WMI scores on four WIAT-II subtests. WMI scores could not be used to differentiate students with Reading Disability (RD), Mathematics Disability (MD) or Generalized Learning Disability (GLD). However, differences between these three LD groups were found on the WISC-IV Verbal Comprehension Index (VCI), Perceptual Reasoning Index (PRI), and marginally on the Processing Speed Index (PSI). Finally, the four WISC-IV Index scores were able to correctly predict group membership in the RD, MD, and GLD groups approximately 70% of the time. / Psychological Studies in Education

abstract: The Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) General Abilities Index (GAI) and Cognitive Proficiency Index (CPI) have been advanced as possible diagnostic markers of Attention-Deficit Hyperactivity Disorder (ADHD). Diagnostic utility statistics were used to test the ability of GAI-CPI difference scores to identify children with ADHD. Participants included an ADHD sample (n = 78), a referred but non-diagnosed hospital sample (n = 66), and a simulated sample with virtually identical psychometric characteristics as the WISC-IV 2,200 child standardization sample. Receiver Operating Characteristic (ROC) analyses were computed to determine the utility of GAI-CPI difference scores to identify children with ADHD. The GAI-CPI discrepancy method had an AUC of .64, 95% CI [0.58, 0.71] for the ADHD sample compared to the simulated normative sample and an AUC of .46, 95% CI [0.37, 0.56] for the ADHD sample compared to the referred but non-diagnosed hospital sample. These AUC scores indicate that the GAI-CPI discrepancy method has low accuracy. / Dissertation/Thesis / M.A. Educational Psychology 2010

abstract: The Native American population is severely underrepresented in empirical test validity research despite being overrepresented in special education programs and at an increased risk for special educational evaluation. This study is the first to investigate the structural validity of the Wechsler Intelligence Scale for Children - Fourth Edition (WISC-IV) with a Native American sample. The structural validity of the WISC-IV was investigated using the core subtest scores of 176, six-to-sixteen-year-old Native American children referred for a psychoeducational evaluation. The exploratory factor analysis procedures reported in the WISC-IV technical manual were replicated with the current sample. Congruence coefficients were used to measure the similarity between the derived factor structure and the normative factor structure. The Schmid-Leiman orthogonalization procedure was used to study the role of the higher-order general ability factor. Results support the structural validity of the first-order and higher-order factors of the WISC-IV within this sample. The normative first-order factor structure was replicated in this sample, and the Schmid-Leiman procedure identified a higher-order general ability factor that accounted for the greatest amount of common variance (70%) and total variance (37%). The results support the structural validity of the WISC-IV within a referred Native American sample. The outcome also suggests that interpretation of the WISC-IV scores should focus on the global ability factor. / Dissertation/Thesis / Ph.D. Educational Psychology 2011

Attention Deficit Hyperactivity Disorder (ADHD) is one of the most prominent neurobehavioral disorders of childhood that is heavily researched and often revised. Deficits in attention/concentration, impulsivity, inhibition, information processing speed, working memory and executive functioning manifest differently according to subtype diagnosis for both children and adults. As a result, previous attempts to construct a unifying theory of ADHD with neural correlates and quantifiable performance discrepancies have resulted in a proliferation of literature reviews citing both significant and insignificant research findings. The purpose of the current study was to construct a homogenous sample of children diagnosed with ADHD and examine purported subtype differences in working memory and information processing speed using the Wechsler Intelligence Scales for Children - Forth Edition (WISC-IV). Sixty participants were selected from archival data from two clinical sites and separated into three groups according to the current DSM-IV-TR ADHD subtype criteria: ADHD Predominately Inattentive type (ADHD-IN), ADHD Predominately Hyperactive/Impulsive type (ADHD-HY), and ADHD Combined type (ADHD-C). Significant differences within groups were revealed on the Coding subtest and Processing Speed Index (PSI) relative to performance on the Perceptual Reasoning Index (PRI). No significant between groups or interaction effects were revealed. While the goal of the current study was aimed at discovering evidence of greater deficits in processing speed by the ADHD-IN group compared to the other two groups, processing speed was reduced for the entire sample providing more evidence of a possible neurological deficit/basis inherent to ADHD. The results of the current study provided minimal evidence of differences on WISC-IV measures of working memory within the current sample. The current study was successful in correcting previous methodological flaws inherent in the relevant literature by constructing a truly homogenous sample of ADHD and provided strong evidence for the necessity of an accurate diagnosis of ADHD subtypes.

Förbättring av den perinatala vården har lett till att fler barn födda för tidigt (FT) idag överlever. Tidigare forskning har visat att den prematura populationen utgör en riskgrupp för neurologiska och fysiska nedsättningar samt negativa hälsopåverkan, bland annat genom en ökad risk för skolrelaterade problem och mobbning. Syftet med denna studie var att undersöka hälsa och behov av stöd hos 6-8 åriga barn (n = 130) födda FT med avseende på fysiska och kognitiva begränsningar, skolrelaterade svårigheter och mobbning. Föräldrarapporterade fysiska begränsningar, skolrelaterade svårigheter och förekomst av mobbning undersöktes genom skattningsformulären Nordiska hälso och familjeformuläret och Child Behavior Checklist (CBCL). Kognitiv förmåga bedömdes genom Wechsler Intelligence Scale for Children – Fourth edition (WISC-IV). Resultatet visade att synskada, trög mage, aptitlöshet och användande av glasögon förekom i större utsträckning hos barn födda mycket för tidigt (MFT) än hos barn födda fullgånget (FG). Resultatet visade även en skillnad i kognitiv förmåga, där barn födda MFT erhöll ett lägre resultat än barn födda FG, bägge grupper låg dock inom normalspannet.  Till skillnad från tidigare forskning visade resultatet inte att barn födda FT skiljde sig åt från barn födda FG avseende skolrelaterade svårigheter eller förekomsten av mobbning. Sammantaget pekar resultaten på att en MFT födsel inte behöver innebära avsevärt större besvär gällande hälsa, skolrelaterade svårigheter eller mobbning hos barn i tidig skolålder, trots en något sänkt generell kognitiv nivå. Möjliga anledningar till detta kan vara få deltagande barn födda extremt för tidigt (EFT) och/eller en effektiv neonatalvård i Sverige. / Recent improvements in perinatal care have led to increased survival of children born premature. Previous research has shown that the premature population constitutes a risk group for neurological and physical impairments and adverse health effects, including an increased risk of school-related difficulties and bullying. The purpose of this study was to investigate the health and support needs of 6-8 year old children (n = 130) born premature, in terms of physical and cognitive impairments, school related difficulties and bullying. Parental reported physical impairments, school related difficulties and the occurrence of bullying were investigated by the Nordic health and family questionnaire and Child Behaviour Checklist (CBCL). Cognitive ability was assessed by the Wechsler Intelligence Scale for Children - Fourth Edition (WISC-IV). The results showed that visual impairment, constipation, loss of appetite and the use of glasses were more frequent in children born very premature than in children born full-term. The results also showed a difference in cognitive ability, where children born very premature received lower results than children born full-term, both groups remained at an average level. In contrast to previous studies, the results did not show a difference between children born premature and children born full-term with regards to school related difficulties or the occurrence of bullying. Overall, the results indicate that a very premature birth need not involve considerably more problems concerning health, school-related difficulties or bullying among children in early school age, despite a slightly lower general cognitive level. Possible reasons for this could be few participating children born extremely premature, and/or an effective neonatal care in Sweden. / The relation between sensory-motor, behaviour functioning and brain development in preterm born children

Objective. This thesis examines the extent to which an intelligence test, the Reynolds Intellectual Assessment Scales (RIAS), aligned with the Carroll-Horn-Cattell theory of intelligence in children ages 4-18 who are either typically-developing or who have a variety of clinical impairments. Other aspects of the RIAS’s construct validity were also evaluated, including its relationship with the Wechsler Intelligence Scales for Children – Fourth Edition (WISC-IV) and whether the RIAS measures intelligence in the same way in typically-developing children as in children with traumatic brain injury (TBI). Methods. Confirmatory factor analysis was used to evaluate the fit of one-factor (g) and two-factor (Verbal Ability and Non-Verbal ability) models in each sample. Configural and measurement invariance of each model were evaluated across the typically-developing group and a group of children with TBI. Correlations between scores on the RIAS and WISC-IV were examined in a group of children with clinical disorders. Results. The two-factor model fit the data of both groups while the one-factor model provided good fit to only the typically-developing group`s data. Both models showed configural invariance across groups, measurement invariance of the two-factor model, and partial measurement invariance of the one-factor model (What`s Missing subtest unconstrained), but scalar invariance was not established for either model. RIAS’s verbal subtests and indexes correlated with theoretically consistent WISC-IV indexes but the RIAS’s nonverbal subtests and indexes did not correlate highly with WISC-IV performance subtests. All RIAS index scores were higher than WISC-IV index scores. Conclusions. Evidence for the interpretability of the NIX and VIX as separate indexes was not found. The VIX is a valid index of crystallized abilities but the NIX does not adequately measure fluid intelligence. The CIX appears to provide a valid measure of g, but may be overly reliant on verbal abilities. The RIAS has significant validity issues that should limit its use in making important decisions. / Graduate

abstract: Standardized intelligence tests are some of the most widely used tests by psychologists. Of these, clinicians most frequently use the Wechsler scales of intelligence. The most recent version of this test for children is the Wechsler Intelligence Scale for Children - Fourth Edition (WISC-IV); given the multiple test revisions that have occurred with the WISC, it is essential to address evidence regarding the structural validity of the test; specifically, that the internal structure of the test corresponds with the structure of the theoretical construct being measured. The current study is the first to investigate the factor structure of the WISC-IV across time for the same individuals. Factorial invariance of the WISC-IV was investigated using a group of 352 students eligible for psychoeducational evaluations tested, on average, 2.8 years apart. One research question was addressed: Does the structure of the WISC-IV remain invariant for the same individuals across time? Using structural equation modeling methods for a four-factor oblique model of the WISC-IV, this study found invariance at the configural and weak levels and partial invariance at the strong and strict levels. This indicated that the overall factor structure remained the same at test and retest with equal precision of the factor loadings at both time points. Three subtest intercepts (BD, CD, and SI) were not equivalent across test and retest; additionally, four subtest error variances (BD, CD, SI, and SS) were not equivalent across test and retest. These results indicate that the WISC-IV measures the same constructs equally well across time, and differences in an individual's cognitive profile can be safely interpreted as reflecting change in the underlying construct across time rather than variations in the test itself. This allows clinicians to be more confident in interpretation of changes in the overall cognitive profile of individual's across time. However, this study's results did not indicate that an individual's test scores should be compared across time. Overall, it was concluded that there is partial measurement invariance of the WISC-IV across time, with invariance of all factor loadings, invariance of all but three intercepts, and invariance of all but four item error variances. / Dissertation/Thesis / Ph.D. Educational Psychology 2012

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