According to its authors, the K-ABC :
was designed to measure ability (intelligence) on the basis of the processing style required to solve tasks”. (Kaufman et al 1987 p.3)
Intelligence was defined as problem solving, and was separated from achievement, which was defined as the knowledge of facts. The assessment battery was constructed to include two scales. Mental Processing and Achievement. Mental Processing corresponds to Fluid abilities/processes, and Achievement corresponds to Crystallised abilities/products as identified by the Cattell-Horn theory (Horn & Cattell 1966). The role of language in responses is minimised, and measures which relate to verbal intelligence are concentrated in the Achievement Scale (Kaufman et al 1987).
The Mental Processing Scale is further sub-divided into two factors. A dichotomous construction of mental processing is common to several theorists and researchers, (Kaufman & Kaufman 1983 cite Bogen, Gazzinga, Kinsborne, Luria, Das and Neisser). Each have their own definition of the two forms of processing, but with common themes. One form of processing is characterised
by descriptions which emphasise analytic, serial and temporal aspects of processing, and the other by descriptions which emphasise holistic, parallel and spatial aspects. These the Kaufman's labelled Sequential and Simultaneous. Tasks contributing to the first of these two factors are best solved by a serial, stepwise approach. Tasks contributing to the second are best solved through the integration of numerous stimuli at one time.
No one theory is represented by the K-ABC, rather the selection of the two processing scales has arisen out of
the confluence of opinion about the two pervasive cognitive processing styles. "{Kauiman personal communication).
Kaufman has also written that
"These components (of mental processing) rest on a convergence of many cognitive and neuropsychologicai theories, most notably theories related to specialisation of the ieft and right cerebrai hemispheres, and to Luria's modei of brain functioning" (Kauiman et al 1987 p.4).
Despite this reference to the localisation of function in the theoretical background to the Kaufman battery, and evidence of a correspondence between the pattern of sub-test performance and hemispheric functioning (Morris & Bigler 1987), the K-ABC is not primarily concerned with describing performance in these terms. The forms of processing being measured are said to have primarily functional correlates, rather than physiological ones (Das 1984). In other words;
" The most important aspect of the K-ABC is that its mental scales are based on well validated and persistently observed cognitive processes. "
and that, Kaufman continued; "These processes translate directly into chiidren's teaming styles and, therefore, have direct applications to educational translation. " (Kaufman personal communication).
In contrast to the information processing approach, traditional intelligence tests tend to select tasks because of the abilities that they measure. The difference between abilities and processes can be explained by the example of memory (Das 1984). Memory is an ability, but success or failure on a memory task does not explain how one memorises. Different tasks can be devised which require the ability to memorise, such as memory for digits, or memory for designs, each also requiring a different processing capacity, the former successive/sequential the latter simultaneous (Das 1984). It is hypothesised that it is only the identification
of the processes that will lead to the development of appropriate intervention programmes (Kaufman & Kaufman 1983).
Studies of Construct Validitv
1. Evidence from the Interpretive Manual
Table 12.14 shows the solutions reported in the Interpretive Manual for three different age groups, four, six and eight year olds, although the solution for the six year olds was only on sub-tests from the Mental Processing Scales. The data supports both the processing/achievement distinction, and the hypothesised division between the two forms of processing. It also indicates developmental trends in the factor loadings on specific sub-tests (see for example the changes in Hand Movements over the three age groups).
Table 12.14 Construct Validity: K-ABC-factor loadings from the US standardisation sample.
K-ABC Sub-test Seq
Age 4 (n=200)
Sim Ach
Age 6 (N=200)
Seq Sim Seq
Age 8 (N=200) Sim Ach Sequential Processing Hand Movements .61 .20 .15 .47 .33 .31 .44 .21 Number Recall .53 .08 .23 .78 .15 .72 .11 .24 Word Order .72 .24 .22 .79 .24 .74 .24 .27
Sim uitaneous Processing
Magic Window .28 .40 .23 Face Recognition .22 .40 .33 Gestalt Closure .14 .72 .33 .12 .55 -.02 .43 .19 Triangles' .38 .44 .18 .17 .75 .08 .61 .24 Matrix Analogies .30 .45 .17 .66 .22 Spatial Memory .27 .63 19 .51 .15 Photo Series .25 .76 .21 .67 .18 Achievem ent Arithmetic .66 .38 .38 .27 .61 .49
(Compiled from Kaufman & Kaufman 1983 p i 05)
A comparison was made between the above solution and the results of a similar procedure carried out on the data from the Kilifi Battery. A three factor solution was requested, with the loading criterion at 0.40., to conform to the solution identified by the K-ABC manual. As evident in Table 12.15. the factor loadings on three factors showed a similar factor structure to the original K-ABC. The first factor consisted in the main of those sub-tests identified as Simultaneous
Processing in the original battery. The exception was Matrix Analogies which had a very high loading on the third factor, and was the only sub-test to do so. This is not an unexpected finding, as Matrix Analogies has been criticised as not providing a pure test of simultaneous processing in younger age groups, and has only shown a high loading on the Simultaneous factor with older children, the loading gradually increasing with age (Das 1984). The high loadings on the second factor were all the sub-tests which were labelled sequential processing in the K-ABC.
Table 12.15 Construct Validity: 3 Factor Solution with factor loadings for the Kilifi Battery .
K-ABC Sub-tests Factors
1 2 3 eigen values 4.70 1.11 .77 % variance 52.20 12.40 8.60 Sequential Processing Hand Movements .11 .80 .24 Number Recall .29 .78 .08 Word Order .20 .80 .02
Sim ultaneous Processing
Magic Window .84 .29 .02 Face Recognition .77 .16 .09 Gestalt Closure .81 .18 .32 Construction .61 .42 .34 Matrix Analogies .22 .17 .93 Achievem ent Arithmetic .48 .63 .26
An Achievement factor was not evident. This is likely to be due to a combined effect of the age of the children and the particular sub-test selected to represent Achievement, namely Arithmetic. For in the K-ABC standardisation sample of pre-schoolers, a stronger association was found between Arithmetic and mental processing sub-scales, than with a separate "knowledge" factor. In the Kilifi Battery Arithmetic was found to load on both the simultaneous and sequential factors, and, similarly to the Kaufman 4 year olds, the higher loading was on the Sequential factor.
2. The Verbal Component
In order to assess the simultaneous-sequential construct amongst a pre-school population, Goldstein et al compared the performance of 40 three year olds on
five K-ABC mental sub-tests with their performance on a number of other tests, including the Stanford Binet, a test of visual-motor integration, and five language measures, including the Peabody Picture Vocabulary Test (Goldstein et al 1986). A description of this study is relevant here because, in addition to raising questions about the verbal component of the K-ABC, it focuses upon a pre school sample, and thus includes the two sub-tests normally excluded for the age group concerned in the current study, but which were applied in the current battery (Magic Window and Face Recognition).
A principal axis factor analysis with varimax rotation was performed on the results, with a loading criterion of 0.40. The three factor solution is reproduced in Table 12.16. In addition to the K-ABC sub-tests, the result of the Picture Vocabulary Test is also reported as it, too, was included among the Kilifi Assessments. Goldstein et al concluded that whilst the first two factors showed an approximation with the sequential\simultaneous dichotomy there were differences which they thought could be better explained by a different interpretation. The justification for this was that the simultaneous sub-tests did not all load on one factor, the exception being Face Recognition which was identified as a non-verbal test, and had a high loading on the third factor. Secondly all the language measures also had moderate to high loadings on the same factor. This factor, factor one, was consequently re-interpreted as a
Vocabulary factor. However, this re-interpretation does not explain the appearance of the visual-motor integration test also on this factor. Nor does it explain the, at least moderate, loadings of several of the language assessments on a separate second factor, in addition to Hand Movements, a sequential sub test.
When the data from the Kilifi battery was subjected to the same procedure (see Table 12.16), adequate loadings were found on only the first two factors, and the simultaneous - sequential dichotomy provided a more adequate interpretation than the Goldstein Vocabulary/Other solution. Thus whilst the Goldstein Study does not provide strong support for the K-ABC factor structure, this may be attributable to methodological issues related to their study design.
Table 12.16 Verbal/Other vs. Simultaneous/Sequential factor loadings K-ABC Sub-tests 1 Goldstein 2 3 1 Kilifi 2 3 Sequential Processing Hand Movements .05 .61 .13 .19 .73 .04 Number Recall .18 .38 .15 .33 .67 -.04
Sim ultaneous Processing
Magic Window .66 .05 .32 .79 .25 -.04
Face Recognition .19 .21 .90 .61 .25 -.09
Gestalt Closure .54 .02 .26 .81 .23 .08
Language
Picture Vocabulary .70 .34 .33 .74 .44 .19
(Compiled from Goldstein et al 1986 p. 892)
However the study does raise the important issue of the relationship between verbal skills and mental processing (Stemberg 1984a, Das 1984, Das et al 1990). Sternberg criticises the attempts by the Kaufmans to separate out verbal skills from mental processing, claiming that vocabulary has been found to be the single sub-test that tends to correlate most highly with full-test IQ (Stemberg 1984a). As the definitions of intelligence commonly used with such tests place an emphasis upon verbal skill, there is an element of circularity in the argument. Furthermore, estimates of non-verbal functioning are often essential to developing an understanding of an individual child's learning difficulties. This is particularly where there is a suspected language impairment (Lassiter & Bardos 1992); where the child is being assessed in a second language (Cummins 1984); or where spoken language is difficult to elicit.
Stemberg’s observations are correct in so far as it is not theoretically logical, nor possible, to separate out verbal skills entirely from mental functioning, but this is not in fact what the Kaufmans claim to be doing (Kaufman & Kaufman 1983). What has been attempted is to reduce the verbal component in the mental processing scales, to make them, for example, more flexible for use with children from different linguistic environments (Cummins 1984). Thus, by excluding the Achievement sub-scale where most of the more verbal assessments are concentrated, it has been possible to apply the K-ABC mental processing scales in a number of different linguistic contexts (Moon 1988, Chounramany et al 1996, Boivin et al 1995).
The verbal component of the two different sub-scales has been a focus for discussion from other quarters (Das et al 1990). In contrast to the Goldstein association between the Simultaneous scale and a verbal factor, Das draws attention to the lack of a verbal task on the Simultaneous scale, suggesting that this factor does not take into account the verbal dimension sufficiently (Das 1984, Das et al 1990). Also demonstrated in the Das papers is the association of the Sequential scale with verbal-memory. This is particularly with older children, due to the changes in factor loadings with age of Hand Movements, the only non verbal test on the scale. High loadings on this sub-test move from the sequential to the simultaneous factor (Das 1984). It is suggested therefore that another way of labelling the two factors is to refer to them as spatial (simultaneous) and
verbaZ-memory (sequential) (Das 1984, Das et al 1990).
A study which can be used to assess these different interpretations of the K-ABC three factor structure is that of Morris and Bigler (1987). The primary aim of the study was to assess the K-ABC findings in the light of a hemispheric specialisation model, but inter-correlations were also calculated between the sub-scales of two different approaches to the assessment of intelligence. It is this which allows for the validity of the factor structure, and its interpretation, to be assessed. 79 children, ranging in ages from 6 to 12 years, and referred for assessment for a potential neurologicalMearning disorder, were tested using both the K-ABC and the Wechsler Intelligence test for Children (WISC-R). Table 12.17 reproduces the results. The correlations reported between the different elements of both batteries were more adequately predicted by the K-ABC Interpretive Manual than either the Goldstein or Das interpretations. In particular, the WISC-R Verbal IQ had the highest correlation with the Achievement scale, than with either processing scale.
Table 12.1 Inter correlations Between K-ABC and WISC-R scales
K-ABC Sub-scales WISC-R Sub-scales
Verbal Performance Full Score
Simultaneous Processing .56 .78 .67
Sequential Processing .58 .35 .51
Mental Processing Composite .67 .71 .70
Achievement .85 .51 .68
It can also be observed that the WISC-R Full-scale IQ correlated most highly with the Mental Processing Composite rather than with any one of the three sub scales. This suggests that both assessments are measuring a common factor, which has been described as "general psychometric intelligence" or "g" (Bonders 1992). This result is contrary to the claim by Sternberg (1984a) that it is the Achievement Scale, rather than the Mental Processing Composite which correlates most closely with other measures of intelligence. However the K-ABC appears to be measuring more than just "g", as the two factor structure remained distinct enough to be isolated even after a general factor had been extracted (Das et al 1990).
3. The Attention Component
In interpreting the results of a study which compared the performance of 51 first grade children on the K-ABC sub-scales with performance on learning tasks designed to be either sequential or simultaneous in their approach (Ayres & Cooley 1986) the investigators noted that, unlike the sub-tests included in the Simultaneous scale none of the Sequential sub-tests required complex cognitive activity" (Ayres & Cooley 1986 p.219). A similar criticism about the lack of complexity was raised by Stemberg (1984a), but there the reference was to the emphasis on rote teaming of this scale. Ayres & Cooley suggest that the most salient feature common to all three sequential sub-tests is an association with attention and distractibility.
The relationship between attention and performance on the K-ABC has been investigated directly using the Test of Variables of Attention, TO VA, (Dupry & Greenberg cited in Chounramany et al (1996)). Using the TOVA, subjects (N = 47, Age = 8) were classified as either having, or not having an attention problem. A significant relationship was found between classification and performance on
all three general scores (Mental Composite, Sequential and Simultaneous Scales). Sub-tests on which a significant difference was also found included two simultaneous and two sequential tests.
In another study which compared the performance of children classified as with or without attention problems, significantly lower scores for the first, problem, group where only found on the simultaneous processing scale (Mantzicopoulos & Morrison 1994). This result, too, does not support the Ayres and Cooley contention.
To investigate the attention performance link further, the factor structure of the Kilifi test battery was re-analysed with the inclusion of a visual search task, which was used as a measure of attention in the current study (see Table 12.18). In this example the results were in line with Ayres and Cooley, as the attention task was found to have a high loading on the same factor as the three sequential tasks.
Table 12.18 Information Processing dichotomy vs. Attention- factor loadings
K-ABC Sub-tests Factors
1 2 e igen values 4.40 1.23 % variance 48.40 13.60 Hand Movements .15 .78 Number Recall .27 .80 Word Order .29 .72 Magic Window .78 .26 Face Recognition .69 .22 Gestalt Closure .88 .15 Construction .73 .39 Matrix Analogies .58 .16 Attention Task .21 .74
4. Developmental Differences in Factor Structure
A second issue was raised by the analysis of the Goldstein pre-school data, that is the possibility of changes in factor structure between different age groups. Kaufman took age changes into account in the design of the battery, by excluding Magic Window and Face-Recognition when these no longer loaded on the appropriate factor, and substituting them with different tests. However, as reported above, no account was taken of the changes in factor loadings of the Hand Movements task (Das 1990), and Das's criticism of the composition of the Sequential factor, as focusing too heavily upon verbal memory tasks, remains for older age groups. This criticism does not appear to be a particular weakness concerning the age and cultural group currently under investigation, as
evidenced by the factor structure reported in Table 12.15, which shows Hand Movements to load, along with other sequential sub-tests, on a single factor.
The reason why changes in factor structure and relative loadings between groups should occur is addressed by Das in his "Six basic statements on coding'
(Das 1984). In Statement four it is written that:
"The same task may be approached either simultaneously or successively (and within each mode of coding, there may be variation in strategies for solution). This would be determined by the interaction of the subject's a) competence in one mode of coding; b) habitual mode of coding when he or she is competent in both modes; and c) task demands that can be modified by instructions. " (Das 1984, p.232).
5. Cross-cultural Validation
The Cummings Studv : Maturation, and changes in experience, such as the introduction of formal schooling, may affect changes in both competence and habitual mode of processing, such that groups of individuals sharing common experiences will alter their approach to a task in a similar manner (Cummings et al 1993). How this might translate into observable and measurable differences in performance between cultural groups is illustrated in an investigation of the relationship between: raw scores on the K-ABC; age; school attendance; and mental processing patterns, in a sample of 48 Sioux children living in a rural reservation area. The children were aged between 8 and 12.5 years old, with each of the five school grade levels included being represented by 8-10 pupils. The majority of the children (67%) spoke English as their first language. Comparisons were drawn between the patterns of performance found here and in other studies. In common with the standardisation sample, a direct correlation was found between raw score and age across all the sub-tests, although this association was significantly stronger in the study sample. School attendance patterns, however, were not found to have any significant affect upon scores. Finally, performance on the Simultaneous Scale was significantly superior to the other two sub-scale measures. This pattern is different to that of the standardisation sample of the K-ABC, where the level of performance on the two scales showed no significant difference (Kaufman & Kaufman 1983). This pattern
was consistent with other samples of rural Native American children (Cummings et al 1993).
It can be concluded that there are two main sources of variation to the othen/vise stable and consistent factor structure of the K-ABC. The first is different age groups, which appear to apply different strategies to the solution of some of the sub-tests. The second is the relationship between different environmental influences which appear to affect the development of processing styles (Bain 1993). Thus, where changes in age or environmental background occur, then a