PART 5 : CATEGORIES OF PSYCHOLOGICAL ASSESSMENT AND COMMONLY USED TESTS WITHIN CATEGORIES

• Jurisdiction: Australia

[60.5210] Introduction

A vast array of tests exist traversing a broad spectrum of areas of psychological inquiry. While this chapter cannot discuss the entirity of either categories of psychological assessment or indeed all the individual tests within each or any category, the following section contains the most commonly used forms of assessment within the most frequent areas of psychological inquiry that may be of interest to the judicial system.

Tests of intellectual functioning

[60.5220] Individual and group administered

These tests may be divided into two categories: individual; and group administered. For most legal assessments, an individual test is preferable because of its higher level of accuracy in measuring intelligence. Also, by its nature, it provides more information through the psychologist being able to observe the subject's performance. The reader should note that a low score on an Intelligence Test does not in and of itself determine that the assessee is Intellectually Disabled: this must be combined with an assessment of adaptive functioning (daily living skills - see below) and supported by corroborative information.

[60.5230] The Wechsler Scales

The most recognised intelligence tests that are utilised world wide are the Wechsler scales. The Wechsler scales have been translated, standardized and adapted for many countries. They vary according to the age range being assesed but in the forensic context, the most widely used are the Wecshler Intelligence Scale for Children - the fifth edition (WISC V) and the Wechsler Adult Intelligence Scale - fourth edition (WAIS-IV) (Weiss et al, 2015)¹. As with most tests, they are constantly updated and revised according to the current literature on measuring intelligence.

The WAIS-IV is used for adults (aged 17 +) and WISC-V is used with children (aged 5-16). At the time of writing, these tests are current versions of Wechsler scales that are used by psychologists to assess intelligence. Both tests provide a range of scores that indicate one's level of functioning across a variety of ability areas that include verbal comprehension, working memory, processing speed, and perceptual reasoning. The WISC V also includes the addition of fluid reasoning as one of the more recent advances in the expansion of the view of intelligence as a 5 factor model. Each test provides an overall estimate of IQ as well as an indication of strengths or weaknesses across each of the 4 or 5 scales. Psychologists will often express results in a general bandwidth (see Table 1 below) and compare results with similar age ranges to provide a percentile score (Weiss et al. 2015). When a psychologist is asked to give expert evidence regarding one's level of intellectual functioning, they will usually refer to the bandwidth and percentiles, so others can gain an understanding of how that person might function compared to others the same age. Table 1 shows the band of scores and their corresponding labels:

TABLE 1 Descriptors for IQ Ranges within the Wechsler Scales

IQ Range	Descriptor (WISC-V)	Descriptor (WAIS-IV)	Percentile Ran:
130 and above	Extremely High	Very Superior	98th and above
120 to 129	Very High	Superior	91-97
110 to 119	High Average	High Average	75-90
90 to 109	Average	Average	25-74
80 to 89	Low Average	Low Average	9-24
70 to 79	Very Low	Borderline	3-8
69 and below	Extremely Low	Extremely Low	2nd and below

Various circumstances may dictate that a full (and lengthy) assessment of intelligence is either unnecessary or impractible. In such cases, where an estimate of intellectual functioning will still assist the court, shortened or abbreviated measures may be appropriate. In this case, the "gold standard" Wechsler scales are still applicable. An example of such is the shortened version of the Weschler scales called the Wechsler Abbreviated Scale of Intelligence (WASI-III), which is a screening tool that indicates intellectual capacity but only takes about 15-20 minutes to complete. It does not provide a comprehensive profile of intelligence but can indicate lower levels of functioning that might require further investigation.

Statistical Properties : The statistical properties of all Weschler scales are impressive and lend support for their use. The overall reliability coefficients for WISC V composite scores range from 0.88 (processing speed) to 0.96 (Full Scale IQ). The WAIS IV is a well-established scale and has high consistency. The test manual states test-retest reliabilities ranged from 0.70 (7 subscales) to 0.90 (2 subscales) over a 2-12 week period. Inter-rater reliability coefficients are also very high, all being above 0.90. The WAIS IV correlates highly (concurrent validity) with the Stanford-Binet IV test (0.88) and has high concordance with various measures of memory, motor speed, attention, and cognitive ability.

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1 The Wechsler Pre School Intelligence (WPPSI) is the scale used for children below the age of five.

[60.5240] Woodcock Johnson

This Woodcock Johnson intelligence tests are commonly used by psychologists who prefer the Cattel-Horn-Carroll (CHC) model of intelligence. The CHC model integrates 2 established models (the Gf-Gc theory of fluid and crystallised intelligence Cattel, 1941: Horn 1965) with Carrol's three-stratum theory of intelligence (1993). There were many similarities between the theories thus they were amalgamated to produce the CHC model. At present, the fourth edition is the latest in the series of tests that were first developed in 1977. The Woodcock Johnson Fourth Edition - Australasian Adaption Test of cognitive ability (WJ-IV: Schrank, McGrew & Mather, 2015) measures intelligence similar to the Weschler scales with a variety of subtests that measure 10 ability areas such as oral vocabulary, number series, verbal attention, letter-pattern matching, phonological processing, story recall, visualisation, general information, concept formation and numbers reversed. Like the Weschler scales, skill areas are grouped into 3 ability cluster scores: Comprehension-Knowledge (Gc); Fluid Reasoning (Gf); and Short Term Working Memory (Gwm). All combine to produce a General Intellectual Ability score (GIA). The GIA provides a comprehensive assessment of functioning that may be representative of the general intellectual ability of the test-taker (like the FSIQ in Weschler tests). For the screening version of the Woodcock Johnson, a Brief Intellectual Ability (BIA) is produced. The BIA is used to screen for possible intellectual difficulties (as per the WASI in Weschler scales) or re-evaluations when a comprehensive assessment is not required. The WJ-IV is an individually administered test.

Statistical Properties: The WJ-IV has reported reliability coefficients that range above 0.80 for subtests and above 0.90 for each of the cluster scores. For the GIA, a median reliability coefficient of 0.85 is reported. Correlations with other measures of intelligence are 0.86 for the WISC-IV (GIA versus FSIQ), 0.84 for the WAIS-IV, 0.72 for the Kaufman Assessment Battery for Children second edition (KABC-II) and 0.80 with the Stanford Binet Intelligence Scales.

[60.5250] Stanford-Binet Intelligence Scales

The Stanford-Binet Intelligence Scale is an individually administered standardized test that measures intelligence in children and adults, from ages 2 plus. The current version of the Stanford Binet Scales is the fifth edition (SB5: Roid, 2003). Unlike the Weschler scales, there are no variants for children or adolescents; all age groups use the same set of tasks. This is sometimes a criticism of the scale because different age ranges complete different tests. For pre-school age children, it is not uncommon for them to score 0 for an item due to difficulty or unwillingness to co-operate. This makes it difficult to compare younger age ranges. The SB5 provides a score for each of the 10 subtests, divided into verbal IQ (VIQ) and Non-verbal IQ (NVIQ) tasks. All combine to provide an overall estimate of IQ name Full Scale IQ (FSIQ), as per the Weschler scales.

The SB5 is marketed as assisting early predication of learning disabilities in children.

Statistical properties: The SB5 boasts reliability coefficients that are very high. For FSIQ, NVIQ and VIQ reliabilities range between 0.95 and 0.98 (average across all age groups). For each of the 10 subtests, reliability ranges between 0.84 and 0.89. Concurrent and citerion validity data were obtained via the Woodcock Johnson, Bender gestalt and Weschler scales.

[60.5260] Differential Ability Scales (DAS)

The Differential Ability Scales are standardised batteries of cognitive and acheivement tests for children only. The tests are individually administered depending on the age range of the child. For those aged 2 years 6 months (2:6) - 6 years 11 months (6:11), they will complete the Early years Cognitive battery. For 7 -17:11, completion of the School-Age Cognitive Battery is appropriate. The current version of the test is the DAS Second Edition (DAS-II; Elliot, 2007). The diagnostic subtests measure a variety of cognitive abilities including verbal and visual working memory, immediate and delayed recall, visual recognition and matching, processing/naming speed, phonological processing, and understanding of basic number concepts. Some of these subtests can be used with children aged 2:6-17:11, while others have specific age ranges. Each of the subtests are combined to produce a General Conceptual Ability Score (GAC).

Statistical Properties: Average internal consistency reliability coefficients for the GCA and non verbal composites are greater than 0.90 for both age range batteries. The range for subtests is 0.77 - 0.95. In relation to validity, the GAC score on the DAS II scale correlates well with the full Scale IQ (FSIQ) scores on the WAIS-IV (0.84) and WPPSI II (0.87).

[60.5270] Kaufman...