Chapter Interpretation of UNIT Performance

Transcription

1 197 7 Chapter Interpretation of UNIT Performance Psychological assessment is more than the administration and scoring of psychological tests. It is a process by which multiple methods and multiple sources of information are meaningfully integrated to understand an individual more fully. As a reliable, valid, and important method and source of information, the UNIT constitutes a central part of the assessment process but should be integrated with other sources of information including reason for referral; presenting complaints; test behavioral observations; findings from other tests; psychoeducational, psychosocial, and medical history; and interviews with the individual, if possible, and collaterals. Current practice and state regulations dictate that intelligence tests must not be interpreted or used in decision making in isolation. The authors and developers of the UNIT concur. Interpretation of UNIT performance changes according to which battery of the test has been administered. The Abbreviated Battery is most appropriate for screening purposes, the Standard Battery for most clinical and educational decision making, and the Extended Battery for in-depth diagnostic assessment. Once the administrative format and results have been obtained, actual interpretation of test performance is conducted in multiple stages and steps in which data are considered successively from the most global and reliable sources (i.e., FSIQ) to increasingly more specific, yet less reliable sources (i.e., scale, subtest, and item scores). Each level of data is examined qualitatively and quantitatively. In brief, three stages of interpretation are described in this chapter:

2 198 Examiner s Manual Stage 1. Interpretation of the FSIQ Stage 2. Interpretation of the Memory, Reasoning, Symbolic, and Nonsymbolic quotients Stage 3. Interpretation of subtest performances These stages are described in further detail here and are also reiterated in the UNIT Interpretive Worksheet page of the record form. In completing the interpretive worksheet for an examinee, the examiner may want to follow the same approach as described here. The current literature on intelligence test interpretation focuses on as many as four types of interpretive strategies: normative, ipsative, cluster, and process. With the normative (interindividual) approach, the examiner compares an individual s performance to expectations based on the collective performance of individuals within a reference group, such as individuals of the same age. With the ipsative (intraindividual) approach, an examinee s performance is compared with other aspects of his or her own performance and thus permits the identification and profiling of relative strengths and weaknesses. Both normative and ipsative procedures have been employed by numerous authors (Bracken, 1984; Elliott, 1986; Kaufman & Kaufman, 1983; McCallum, 1991; McGrew, 1994; Sattler, 1988) and are commonly used by practitioners. With regard to interpretive strategies for the UNIT, the emphasis is on the traditional normative and ipsative approaches. Practitioners may also choose to utilize other interpretive strategies, such as cluster and process approaches (not addressed in depth here). With the cluster approach, described by Glutting, McDermott, & Konold (1997), cluster-analytic procedures are used to derive a normative subtest-profile taxonomy. It enables the comparison of an examinee s profile of subtest scores to several core profile types close to his or her general ability level to determine an optimal match as well as the commonality of the profile. The process approach, advocated by Kaplan (1983, 1988; Milberg, Hebben, & Kaplan, 1996), emphasizes the identification of problem-solving strategies, types of errors, and qualitative aspects of test performance rather than the final scores. Interpretation Guidelines The UNIT interpretation scheme follows the logical sequence of interpreting performance on the instrument from the Full Scale, to the four quotients, and, finally, to subtests and individual items. Stage 1. Interpretation of the FSIQ The first stage of UNIT interpretation requires describing the examinee s Full Scale performance both quantitatively (e.g., standard scores, confidence intervals, percentile ranks) and qualitatively (e.g., descriptive classi-

3 Interpretation of UNIT Performance 199 fications). The Full Scale is the most reliable data source in the UNIT because it includes sources of variation from all of the subtests and scales that compose the test. As such, this molar data source is more reliable than the more molecular scores that compose it. The FSIQ is also likely to be the best predictor of important real-world outcomes, particularly academic and vocational success (Sattler, 1992). Standard Score The UNIT FSIQ (as well as the standard scores on the four additional global scales) is based on a normative population mean of 100 and standard deviation of 15. These values mean that 68% of examinees in the normative sample obtained FSIQs between 85 and 115, approximately 95% of the sample obtained scores between 70 and 130, and slightly more than 99% of the sample obtained scores between 55 and 145. Because intelligence is a construct that fairly well conforms to the traditional normal bell curve, standard scores on the UNIT scales can be considered in a comparable light with IQs obtained on other intelligence tests based on the same metric (i.e., M 100, SD 15), such as the WISC III (Wechsler, 1991) and the WJ R (Woodcock & Johnson, 1989/1990). Percentile Rank A percentile rank describes an individual s relative position in a population, with the 50th percentile representing performance at the midpoint of those in the sample. Consistent with the manner in which the UNIT scale scores fit the normal curve, coinciding percentile ranks are predictably associated with their respective scale scores. The foundation for percentile ranks, based on z scores, can be examined in most statistics texts that provide information about the normal curve and area under the curve. The UNIT manual employs this statistical convention and provides percentile ranks for all scale and subtest scores. Confidence Interval Because error is normally distributed, all observed scores should be considered as occurring within a band of confidence that frames the estimated true score by one or more standard errors of estimate, as determined by the level of confidence desired (e.g., 90% or 95%). Confidence intervals built around estimated true scores define the probability that a given range of scores will include the examinee s hypothetical true score. A true score is defined as the hypothetical average that would be obtained from repeated testings, free from the effects of error, such as guessing, practice, or fatigue. Descriptive Classification Performance on the UNIT Full Scale and composite scales may be described qualitatively through the use of several classification terms that serve as broad descriptors of the examinee s level of intellectual functioning. These terms (listed in Table 7.1 and in Appendix Table C.1) range from Very Superior to Very Delayed and are intended to constitute a way of briefly and accurately communicating information. The use of these terms

4 200 Examiner s Manual should never be considered a substitute for a more complete description of an examinee s cognitive abilities and relative strengths and weaknesses. Stage 2. Interpretation of the Memory, Reasoning, Symbolic, and Nonsymbolic Quotients The second stage of UNIT interpretation focuses on the variability among the Memory, Reasoning, Symbolic, and Nonsymbolic quotients in order to determine the representativeness of the FSIQ as an estimate of overall intellectual ability. When an examinee s scores on these four scales exhibit significant variability, the FSIQ may not serve as a good estimate of global ability, and performance on the UNIT scales should be interpreted. The first step of UNIT interpretation at the scale level is an examination of standard scores, percentile ranks, and confidence intervals (all provided in Appendix B), and descriptive classifications (Appendix Table C.1) for each of these primary and secondary scales. The examiner should then consider the comparability of the standard scores on the four scales (i.e., Memory vs. Reasoning and Symbolic vs. Nonsymbolic). Given the factor structure of the UNIT, the examiner should first examine performance on the two primary (Memory and Reasoning) scales and then on the two secondary (Symbolic and Nonsymbolic) scales. For both comparisons, the difference between the two scores should be examined for statistical significance and commonness or rarity. Appendix Tables D.1 and D.2 provide the necessary information for determining whether the difference between two scale scores is meaningful. The meaningfulness of a difference is based on both its statistical significance and its frequency. The significance of a difference between two scores is based on the magnitude of the difference. Appendix Table D.1 provides the differences

5 Interpretation of UNIT Performance 201 between the Memory and Reasoning quotients and between the Symbolic and Nonsymbolic quotients at three levels of significance: 90%, 95%, and 99%. Differences are provided by age group and for the Standard and Extended batteries. If the difference between two scores is statistically significant, that is, so large that it would not likely occur by chance alone, such a difference should be considered important at least for the purposes of exploring possible reasons for the difference. However, statistically significant differences are not necessarily clinically meaningful or rare. A probability of 95% is recommended for determining statistical significance. If one or both of the differences between the scores on the Memory and Reasoning scales and between the scores on the Symbolic and Nonsymbolic scales are statistically significant, the obtained UNIT FSIQ should be considered a less-than-optimal index of the examinee s overall intellectual abilities. The relative frequency the commonness or rarity of a statistically significant score difference within the population is another important indicator of that discrepancy s meaningfulness. Appendix Table D.2 provides the cumulative percentages (frequencies) across ages in the entire standardization sample of Memory Reasoning discrepancies and Symbolic Nonsymbolic discrepancies. The relative frequency of differences between scores addresses an issue separate from statistical significance. As mentioned previously, statistical significance is the probability that an observed score difference will occur in the population by chance alone. However, differences of that magnitude may occur in the normative population with considerable frequency because of real differences that exist in the abilities of individuals within the population rather than because of chance factors. A statistically significant discrepancy that occurs very frequently is generally of less concern than a statistically significant discrepancy that is also rare. Table 7.2 provides interpretive hypotheses based on statistically significant and rare differences between scores on the primary scales and between scores on the secondary scales. In summary, the specific steps for interpreting performance on the primary and secondary scales are as follows: 1. Based on the sums of subtest scaled scores, the Memory, Reasoning, Symbolic, and Nonsymbolic standard scores and the confidence intervals and percentile ranks for those scores are determined. This information is provided in Appendix B. Each of the standard scores for these scales can be based on the sum of either two subtest scaled scores (Standard Battery) or three subtest scaled scores (Extended Battery). A qualitative description of each standard score can also be determined (Appendix Table C.1). 2. Differences between the standard scores on the Memory Quotient and Reasoning Quotient (the primary scales) and between the scores on the Symbolic Quotient and Nonsymbolic Quotient (the secondary scales) are examined for statistical significance (Appendix Table D.1) and frequency (Appendix Table D.2).

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7 Interpretation of UNIT Performance 203

8 204 Examiner s Manual 3. Tentative interpretive hypotheses (see Table 7.2) are generated to explain any discrepancy that is statistically significant and rare. External sources of information are used to corroborate any hypotheses. 4. Whether or not differences between the scale scores exist, a significant discrepancy between the scores on the subtests composing a scale may mean that the scale score is not representative of the intended ability. Subtest score interpretation, described next, is used to determine whether subtest score variability rather than scale score variability is the most appropriate level of explanation. Stage 3. Interpretation of Subtest Performance Although significant score deviation on the scales is considered an important index for interpreting the FSIQ, examiners should be aware that nonsignificant variability among scale scores does not necessarily mean that a test profile contains no significant variability. Subtest scores may yield statistically significant but off-setting differences that result in similar scores across scales. Therefore, the determination of whether the FSIQ is a reasonable estimate of overall cognitive functioning is based not only on scale scores but also on subtest scores. At this level of interpretation, all UNIT subtest scaled scores may be compared, with emphasis placed on how individual subtest scores might have affected the FSIQ and the primary and secondary scale scores. Subtest score interpretation may be useful for determining an individual s cognitive strengths and weaknesses, even if findings from analyses of the scale scores are unrevealing. Traditionally, examiners have choosen to interpret subtest performance relative to normative expectations, in terms of test-age equivalents (provided in Appendix Table C.2), or ipsatively. Both the interpretation of subtest performance relative to performance on other subtests and the interpretation of the pattern of subtest scores within a scale represent an ipsative approach. Ipsative interpretation (i.e., intraindividual score analysis) can be conducted by several methods, depending on the nature of the score variability (McCallum, 1991). Ipsative interpretation is most appropriate for the six-subtest Extended Battery; however, the same principles and guidelines are also used for interpreting performance on the four-subtest Standard Battery. The twosubtest Abbreviated Battery is best used as a good screening measure of intelligence and is not well suited to profile analysis. Because the Abbreviated Battery consists of one memory subtest and one reasoning subtest, it is possible to obtain a very gross estimate of the examinee s memory and reasoning abilities from this battery.

9 Interpretation of UNIT Performance 205 Subtest Variability Within Scales The evaluation of subtest score variability within a scale or battery is based on the difference between each subtest score or between a subtest score and the mean of the subtest scores contributing to that scale or battery. The evaluation of subtest score variability should be completed for each scale, that is, for the Memory, Reasoning, Symbolic, and Nonsymbolic quotients. Variability is minimal when there are no statistically significant differences among the subtest scaled scores or between any subtest score and the mean of the subtest scores. When minimal variability exists, the examiner can conclude that the examinee demonstrated relatively uniform performance within a scale and infer that subtest performances contributing to scale performance are uniform and consistent. When considerable variability exists, in-depth interpretation is necessary. Subtest specificity values should be considered before individual subtest scores are interpreted. Subtest Variability Within the Abbreviated Battery The two-subtest Abbreviated Battery provides a reasonable estimate of an examinee s overall intellectual functioning. It is possible, however, to compare performance on Symbolic Memory and Cube Design to determine a memory reasoning difference in abilities, with the following steps: 1. The difference between the scaled scores on Symbolic Memory and Cube Design (found in Appendix A) is determined. At this point, positive and negative values are ignored. 2. The statistical significance of any discrepancies between two subtest scores is determined. Appendix Table D.4 provides statistically significant discrepancies between subtest scores at the 90%, 95%, and 99% levels of significance. 3. The frequency commonness or rarity of a statistically significant difference must be determined. Appendix Table D.5 provides the cumulative percentages (across age groups) of the standardization sample obtaining various differences between subtest scores. 4. If a difference is statistically significant, then some reasonable hypotheses might be made. The hypotheses may have increased clinical relevance if the difference is also rare. The difference is attributable to discrepancies in symbolic mediation versus nonsymbolic mediation. The difference is due to an interaction between the abilities assessed by the primary and secondary scales. 5. Whether or not a statistically significant difference between subtest scores exists, intrasubtest variability (i.e., item response patterns) can be examined. Variations in item performance may be related to attentional problems, learning disabilities, or other conditions. Subtest Variability Within the Standard Battery 1. For each scale Memory, Reasoning, Symbolic, and Nonsymbolic the difference between the scaled scores on the two subtests contributing

10 206 Examiner s Manual to the scale is determined. At this point, positive and negative values are ignored. 2. The statistical significance of any discrepancies between two subtest scores is determined. Appendix Table D.4 provides statistically significant discrepancies between subtest scores at the 90%, 95%, and 99% levels of significance. 3. The frequency commonness or rarity of a statistically significant difference must be determined. Appendix Table D.5 provides the cumulative percentages (across age groups) of the standardization sample obtaining various differences between subtest scores. 4. If there is no statistically significant discrepancy, then the score on the scale may be interpreted with confidence. If a difference is statistically significant, then the unique and shared abilities associated with each subtest should be considered for interpretation as a strength or weakness. 5. Whether or not a statistically significant difference between subtest scores exists, intrasubtest variability (i.e., item response patterns) can be examined. Variations in item performance may be related to attentional problems, learning disabilities, or other conditions. Subtest Variability Within the Extended Battery 1. For each scale Memory, Reasoning, Symbolic, and Nonsymbolic the difference between the scaled score on each of the three subtests contributing to the scale and the mean of those three subtest scores is determined. At this point, positive and negative values are ignored. 2. The statistical significance of any discrepancies between the subtest score and the mean of the subtest scores is determined. Appendix Table D.3 provides statistically significant discrepancies between subtest scores and the means of subtest scores at the 90%, 95%, and 99% levels of significance. 3. The frequency commonness or rarity of a statistically significant difference must be determined. Appendix Table D.3 also provides the cumulative percentages of the standardization sample obtaining various differences between a subtest score and the mean of subtest scores. 4. If there is no statistically significant discrepancy, then the score on the scale may be interpreted with confidence. If a difference is statistically significant, then the unique and shared abilities associated with the subtest should be considered for interpretation as a strength or weakness. 5. The abilities associated with individual subtests (Table 7.3) are used to generate interpretive hypotheses or potential explanations for scale performances. (The abilities assessed by the subtests are discussed in detail later in this chapter.) The pooled subtest approach (described next) may be used for examining relative strengths and weaknesses when within-scale variability is not present.

11 Interpretation of UNIT Performance 207 Pooled Subtest Variability When there are no significant differences between scale scores, that is, when the Memory Quotient is commensurate with the Reasoning Quotient and the Symbolic Quotient is commensurate with the Nonsymbolic Quotient, but scores on the individual subtests within the two scales vary considerably, then the pooled procedure of interpretation may be used. This pattern assumes that performance variability is characterized more by variability among the unique abilities of subtests rather than by variability among the constructs underlying the test (i.e., memory, reasoning, symbolic mediation, and nonsymbolic mediation). The pooled interpretation procedure is similar to the procedure for determining subtest variability within scales. With the pooled approach, however, the extent to which each individual subtest score deviates from the average of all the subtest scores, that is, the mean of all four (Standard Battery) or six (Extended Battery) subtest scores, is determined. In this way, outliers (i.e., scores that differ significantly from the overall subtest mean) are identified. The following steps are required to conduct the pooled interpretive process. 1. For the four-subtest Standard Battery or for the six-subtest Extended Battery, the difference between each of the scaled scores on the four or six subtests contributing to the battery and the mean of all four or all six subtest scores is determined. 2. The statistical significance of any discrepancies between the subtest score and the mean of the subtest scores is determined. Appendix Table D.3 provides statistically significant discrepancies between subtest scores and the means of subtest scores at the 90%, 95%, and 99% levels of significance. 3. The frequency commonness or rarity of a statistically significant difference must be determined. Appendix Table D.3 also provides the cumulative percentages of the standardization sample obtaining various differences between a subtest score and mean of subtest scores. 4. A statistically significant difference necessitates further analysis: A subtest score that is significantly greater than the mean score reflects a strength; a subtest score that is significantly less than the mean score reflects a weakness. Table 5.21 and the subtest-by-subtest analysis section later in this chapter are used to determine whether individual subtests possess sufficient specificity to be interpreted as measuring a unique cognitive ability. The abilities associated with individual subtests (Table 7.3) are used to generate hypotheses or potential explanations for individual subtest strengths or weaknesses (i.e., to resolve discrepant subtest scores and inconsistent subtest patterns).

12 208 Examiner s Manual An apparent strength or weakness in an ability can be further examined by comparing performance on comparable subtests (and abilities) assessed by other tests concurrently administered or in light of previous assessment (i.e., examination of historical data). Item response patterns within a subtest can be examined for clues about specific areas of ability or inability. For example, the examinee might have passed Analogic Reasoning items based on concrete, recognizable objects but failed items based on abstract figural designs. Abilities Assessed by the UNIT Subtests The UNIT subtests measure, in order of importance, global intelligence, reasoning and short-term memory, and symbolic and nonsymbolic mediation. In this and the following section, the abilities presumed to underlie the UNIT subtests are described in depth. The primary and secondary abilities associated with each subtest are presented, as well as a subtestby-subtest summary of psychometric properties and distinctive aspects. Table 7.3 provides a description of the primary and secondary abilities presumed to be assessed by each of the UNIT subtests. Each subtest has its own primary and secondary task demands that are different from those of the other subtests. After conducting normative and ipsative subtest analyses with the UNIT, the examiner may wish to consult Table 7.3 to develop hypotheses about the examinee s test performance and cognitive abilities; these hypotheses should be developed in light of the examinee s referral problem, performance on the UNIT, classroom and test-session behaviors, academic work samples, third-party reports, prior educational and cultural experiences, and other test results. For example, young examinees who have had very little prior formal or informal educational experiences may perform especially poorly on the Mazes subtest because of the requisite paper-and-pencil skill necessary to perform the task or because the test may be sensitive to prior experience with maze-like activities. In order for a lack of paper-and-pencil experience to be a viable hypothesis, the examiner should analyze the examinee s level of comfort while handling the pencil and paper during the subtest. In a systematic fashion that takes into account multiple sources of data, over a variety of settings and times, the examiner should be able to develop viable hypotheses about the examinee s performance on the UNIT. Bracken and Fagan (1988) found that experienced examiners demonstrated only moderate levels of agreement with each other and with test authors when asked to identify specific underlying abilities that were related to various cognitive subtests. As a result of the disparity among raters, Bracken and Fagan recommended that test authors operationally define the underlying abilities that they presume underpin their respective tests. Consistent with Bracken and Fagan s recommendation, operational definitions of the abilities presumed to underlie the UNIT subtests are provided here.

13 Interpretation of UNIT Performance 209 Abstract Thinking Abstract thinking is the ability to identify subtle nuances and characteristics of objects, recognize their classification or organization, and generalize beyond obvious functions, attributes, or associations to more complex, less

14 210 Examiner s Manual apparent levels. Figural analogies, for example, may require the identification of subtle changes in structural relationships as an object evolves or appears to move in space. Analogies that include recognizable objects may be concrete (e.g., milk is to glass as coffee is to cup) or abstract (e.g., blossom is to cucumber as egg is to chicken). When examinees are required to analyze, reproduce, or evaluate aspects of unfamiliar two- or threedimensional geometric designs, abstract thought is generally required. Analysis Analysis is the division of a whole into its component parts and the consideration of each part with respect to the whole. Attention to Detail Attention to relevant detail, while ignoring irrelevant detail, is the extent to which individuals can attend to, perceive, discern, and appreciate small and sometimes subtle but important stimulus characteristics. Some individuals detect only the grossest characteristics of an object, concept, setting, or scene, whereas other individuals attend to detail quickly and then deftly identify and discriminate all of the essential stimulus components. Concentration Focused and sustained attention, while ignoring extraneous distractions, is the hallmark of concentration. Tasks that require transforming or coding information, complex analyses, or sustained problem-solving efforts all are solved more readily by individuals who concentrate well. Some complex tasks, however, can be completed by repeated trial-and-error efforts (e.g., Cube Design) that require flexibility of thought and persistence but that do not require sustained concentration. The key to concentration is the ability to sustain attention while ignoring distractions that would otherwise foil problem-solving efforts. Concept Formation Concept formation is the process of identifying and synthesizing the defining characteristics of related objects such that the objects become grouped and perceived as part of a larger, meaningful category. Evaluation Evaluation is the summative step in any problem-solving activity. After an examinee has considered and attempted strategies to solve a problem, the evaluative step is essential for determining whether the specified strategies provided a successful solution. Some tasks, such as UNIT Mazes, require evaluation at every decision point encountered throughout the completion of the maze, whereas other tasks require partial completion (e.g., Cube Design) or a final solution (e.g., Analogic Reasoning) before evaluation is beneficial. Holistic Processing Holistic processing includes the reception and integration of a collection of stimuli as a united whole, rather than as disparate parts. Holistic processing emphasizes the synthesis of stimuli more than the analysis of stimuli.

15 Interpretation of UNIT Performance 211 Impulse Control Impulse control is the ability to inhibit responding. The presentation of test stimuli is designed to elicit a response from examinees. Individuals who delay their response until they have taken the necessary time to fully process the stimuli are said to have impulse control. Individuals who respond too quickly, responding before they have had an opportunity to carefully process the information, are lacking in impulse control. Nonsymbolic Mediation Nonsymbolic mediation is the interpretation or consideration of stimuli without the attachment of verbal labels or symbolic representations to the stimuli. In nonsymbolic mediation, stimuli are taken at face value, without additional intended meaning (e.g., a cube does not symbolically represent another object). Nonverbal Reasoning Nonverbal reasoning entails the solution of problems that are abstract. The construction of abstract geometric designs and the completion of mazes are examples of tasks that are nonverbal and that do not lend themselves to verbal mediation processes such as labeling, categorization, conceptualization, or to solution through a verbal approach. Paper-and-Pencil Skill This experiential, school-related behavior is assessed whenever the examinee is required to print, write, draw, trace, or compute with the use of both pencil and paper. Prior experience and facility with use of paper and pencil are important for school success. Perception of Abstract Stimuli Perception of abstract stimuli includes the ability to identify, recognize, differentiate, and appreciate relevant characteristics associated with visual stimuli. Abstraction is required to discern the (often artificial) meaning attached to stimulus characteristics. Simulated letters, symbols, geometric patterns, and objects represented in items are examples of abstract representations. Appreciation of an abstraction requires the basic ability to perceive the nuances of the figure and the relationships among its component parts. Perception of Meaningful Stimuli This ability reflects the examinee s awareness and appreciation of the representation of common objects, pictures, and concepts. A picture of a flower, for example, must be recognized as a flower before an examinee can complete a more complex conceptual analogy that contrasts plants and animals; that is, the picture must take on a concrete representation of an actual object. Perceptual Organization Perceptual organization is the meaningful interpretation and arrangement or rearrangement of visual stimuli to solve a problem. Perceptual

16 212 Examiner s Manual organization requires a full range of perceptual skills, including visual discrimination, visual figure ground separation, perspective taking, visual closure, and so on. Successful perceptual organization also requires a variety of operations, including analysis, synthesis, discrimination, manipulation, and evaluation of stimuli as part of the problem-solving activities. Planning Ability The hallmark of effective behavior is the ability to make sound and efficient plans, execute the plans in a deliberate and reflective fashion, evaluate the efficacy of the plans, and modify future plans accordingly. Planful behavior emphasizes logic and reflective thought, rather than emotion and impulsive thought and actions. Reasoning Reasoning is the use of systematic, rational, and logical thought to draw conclusions, form inferences, render judgments, or solve problems. Reproduction of a Model This ability requires the examinee to construct a replica of a model that is either pictured or constructed by the examiner (e.g., block patterns, cube designs, drawn figures). It is important to note that reproduction of a model requires that the model remain in sight while the examinee attempts to construct the replica. If the model is not left in the examinee s view at all times, successful task completion may be influenced more by memory than by the ability to construct a matching model. Sequential Processing Sequential processing requires the examinee to perceive, analyze, code, and operate on successive bits of information in a step-by-step fashion. The temporal consideration and treatment of stimuli by the examinee is the characteristic that emphasizes the sequential aspects of a task. Simultaneous Processing Simultaneous processing requires awareness of the juxtaposition of components in an overall gestalt, represented typically in a visual display. Tasks that present stimuli in a visual gestalt, where the order or temporal sequence of the response is irrelevant, are most efficiently processed simultaneously. Spatial Memory items, which present an array of green and black circles positioned in random locations on a stimulus grid, are an example of a simultaneous-processing task. For this activity, the examinee must note the visual display and respond by placing response chips in the correct locations on a response grid. Spatial Orientation Spatial orientation is the ability to position oneself in reference to a location or direction (e.g., directionality) or to perceive, analyze, organize, or reorganize relevant stimuli on two or more dimensional spatial planes to solve a problem. In such problems, space and directionality are relevant

17 Interpretation of UNIT Performance 213 variables, and the correct orientation and alignment of stimuli and responses within that spatial configuration is essential. Symbolic Mediation Symbolic mediation is the interpretation or use of symbols (e.g., signs, lett e r s, rebus ch a r a c t e r s, f l a g s, gestures) to represent specific objects, c o n c e p t s, categories, actions, or images. During symbolic processing, symbols take on the value and meaning of specific words and are mediated verbally. Synthesis Synthesis requires the combination of disparate stimulus components to create a meaningful whole. Arranging and connecting various pieces of a puzzle to create a completed picture is an example of synthesis. Three-Dimensional Representation Three-dimensional representation is the presentation of a problem in a manner that requires the examinee to attend to and consider stimuli presented on three distinct spatial planes (i.e., vertical/height, horizontal/ width, and depth). In the Cube Design subtest, three sides (i.e., top, left, and right sides) of the cube models are pictured; the examinee must reproduce the three-dimensional models by making all three faces of the reproduction match the stimulus depiction. Verbal Mediation Verbal mediation is the covert vocalization that examinees use to solve problems. Also referred to as subvocalization, this verbal behavior requires neither verbal reception nor expression but is employed on tasks where the stimuli are conceptual or categorical (e.g., conceptual analogies). Not all tasks lend themselves to verbal mediation, however. Some tasks (e.g., Spatial Memory) have salient characteristics that are not easily labeled, categorized, or considered in relational terms to facilitate solution through verbal mediation. Visual Motor Integration Visual motor control requires the perception of visual stimuli combined with a fine motor response. The combination of visual perception and small muscle execution abounds in activities such as writing, drawing, and manipulating small materials all of which are important in educational and adaptive functioning. From an adaptive consideration, visual motor integration is necessary for buttoning, zipping, tying, and snapping clothing, outerwear, shoes, and so on. Several UNIT tasks require examinees to view, manipulate, organize, and rearrange or place, small chips, cards, and three-dimensional cubes. The paper-and-pencil skill necessary to negotiate the narrow passages in the Mazes subtest requires specific, educationally relevant visual motor integration. Visual Short-Term Memory Visual short-term memory requires immediate recall of multiple stimuli after those stimuli have been presented to the examinee in a visual array for a short duration (e.g., seconds).

18 214 Examiner s Manual Working Under Time Constraints Tasks that have time limits, whether generous or restricted, require the examinee to be conscious of time as an important task element. Some tasks have no finite time limits for completion, whereas others do. Of those tasks that have predetermined time limits, some present many easily solved problems that emphasize examinee speed and response accuracy. Other timed tasks are power oriented and present fewer problems and allow generous time limits. Both of the UNIT timed subtests (i.e., Cube Design and Mazes) present power tasks that allow generous time limits and emphasize complex problem solution and that avoid the quick response requirements of speeded tasks. Subtest-by-Subtest Analysis A summary of each subtest s psychometric properties and distinctive aspects is presented in this section. Much of the statistical information appeared in earlier chapters. The reliability coefficients, first presented in Table 5.2, are split-half coefficients corrected with the Spearman Brown formula and averaged across all ages with Fisher s z transformation. The test retest stability coefficients, first reported in Table 5.6, are corrected for the variability of scores on the first testing. The g loadings are factor pattern coefficients for an unrotated, one-factor solution derived from a principal components analysis. Subtest specificity is drawn from Table 5.21 and represents a partitioning of sources of variance according to procedures utilized by Kamphaus (1993), Kaufman (1979, 1994), Sattler (1988), and Bracken et al. (1993). Subtest interrelationships (i.e., most related to, least related to) are based on average subtest intercorrelations across ages, originally reported in Table Finally, the primary and secondary abilities and likely subtest correlates are logically derived. Symbolic Memory Reliability Split-Half.85 Test Retest.72 g Loading Standard Battery Extended Battery Subtest Specificity vs. 32% Error Variance 15%.74 (Good).73 (Good) Most Related to Spatial Memory and Object Memory Least Related to Mazes Primary Abilities Shared With Other Subtests Attention to Detail Concentration Perception of Meaningful Stimuli Sequential Processing Symbolic Mediation Verbal Mediation Visual Short-Term Memory

19 Interpretation of UNIT Performance 215 Secondary Abilities Shared With Other Subtests Concept Formation Perceptual Organization Visual Motor Integration Correlates of Subtest Performance As a measure of short-term sequential and symbolic memory, an examinee s performance on the Symbolic Memory subtest may predict such behaviors as the examinee s ability to attend to and distinguish important from irrelevant information; organize, recall, and follow multistep directions; sequence verbal information meaningfully (e.g., story telling; reading decoding); understand and compute multistep mathematics story problems; ignore extraneous, competing information during problem solving; and concentrate on the interrelationships between salient variables. Cube Design Reliability Split-Half.91 Test Retest.85 g Loading Standard Battery Extended Battery Subtest Specificity vs. 37% Error Variance 9%.78 (Good).73 (Good) Most Related to Spatial Memory and Analogic Reasoning Least Related to Object Memory and Mazes Primary Abilities Shared With Other Subtests Abstract Thinking Analysis Attention to Detail Evaluation Holistic Processing Nonsymbolic Mediation Nonverbal Reasoning Perception of Abstract Stimuli Perceptual Organization Reasoning Reproduction of a Model Simultaneous Processing Spatial Orientation Synthesis Three-Dimensional Representation Visual Motor Integration Working Under Time Constraints Secondary Abilities Shared With Other Subtests

20 216 Examiner s Manual Correlates of Subtest Performance Performance on the Cube Design subtest may predict the examinee s mechanical or graphic (e.g., artistic, drafting, geometry) competence; ability to divide aspects of problems into discrete parts for examination and recombination to provide a viable solution; tenacity in complex future problem-solving situations; reaction to activities that have deadlines or specific time limits; flexibility in evaluating and modifying solution strategies; and ability to orient in and around his or her environment (e.g., reading maps, following spatial directions). Spatial Memory Reliability Split-Half.81 Test Retest.68 g Loading Standard Battery Extended Battery Subtest Specificity vs. 21% Error Variance 19%.79 (Good).77 (Good) Most Related to Symbolic Memory and Cube Design Least Related to Mazes Primary Abilities Shared With Other Subtests Attention to Detail Concentration Nonsymbolic Mediation Perception of Abstract Stimuli Perceptual Organization Simultaneous Processing Spatial Orientation Visual Short-Term Memory Visual Motor Integration Secondary Abilities Shared With Other Subtests Correlates of Subtest Performance Performance on the Spatial Memory subtest may predict such future behaviors as the examinee s ability to view the totality and central nature of problems; attend to, process, and recall visual details (e.g., editing, photography, chess); remember the crux of information, rather than the sequence in which the information was presented; concentrate on a problem until the problem is well understood; disassemble and reassemble objects (e.g., motors, computers) by memory; and sensitivity and awareness to minor changes in the environment (e.g., noting the addition or subtraction of important elements).

21 Interpretation of UNIT Performance 217 Analogic Reasoning Reliability Split-Half.79 Test Retest.72 g Loading Standard Battery Extended Battery Subtest Specificity vs. 26% Error Variance 21%.74 (Good).73 (Good) Most Related to Cube Design and Object Memory Least Related to Mazes Primary Abilities Shared With Other Subtests Abstract Thinking Analysis Concept Formation Evaluation Perception of Meaningful Stimuli Reasoning Symbolic Mediation Synthesis Verbal Mediation Attention to Detail Perception of Abstract Stimuli Perceptual Organization Sequential Processing Simultaneous Processing Spatial Orientation Secondary Abilities Shared With Other Subtests Correlates of Subtest Performance Performance on the Analogic Reasoning subtest may predict such future behaviors as the examinee s ability to understand and solve conceptual problems; determine the interrelationships between objects and actions (e.g., understand cause-and-effect relationships); produce rational arguments, based on sequential logic; generalize learned principles to solve new problems (e.g., applying centrifugal force to cause sediments to settle in a vial); acquire and use rules in a systematic fashion. Object Memory Reliability Split-Half.76 Test Retest.60 g Loading Standard Battery Extended Battery N.A..71 (Good)

22 218 Examiner s Manual Subtest Specificity vs. 26% Error Variance 24% Most Related to Symbolic Memory and Spatial Memory Least Related to Mazes Primary Abilities Shared With Other Subtests Attention to Detail Concentration Perception of Meaningful Stimuli Simultaneous Processing Symbolic Mediation Verbal Mediation Visual Short-Term Memory Concept Formation Perceptual Organization Visual Motor Integration Secondary Abilities Shared With Other Subtests Correlates of Subtest Performance Performance on Object Memory, unlike the other memory subtests, is based on three specific skills: the ability to discern nuances in physical characteristics; the ability to recognize and recall, as opposed to reproducing, objects viewed; and the ability to rule out distracters that were not among the original stimuli presented. These unique abilities may predict such future behaviors as the examinee s ability to attend to and discern minor details (e.g., note minor elements of a story, note graphical configurations); observe, note, and recall changes made in the structure of sports teams (i.e., who plays which position); recall relevant information and ignore irrelevant information; remember faces, facts, and objects when presented in a new or different setting (e.g., recognizing people across social contexts); and discern when something (e.g., plan, budget, scene) has been altered. Mazes Reliability Split-Half.64 Test Retest.58 g Loading Standard Battery Extended Battery Subtest Specificity vs. 45% Error Variance 36% N.A..44 (Poor) Most Related to Cube Design and Spatial Memory Least Related to Object Memory Primary Abilities Shared With Other Subtests Concentration Evaluation

23 Interpretation of UNIT Performance 219 Impulse Control Planning Ability Reasoning Nonsymbolic Mediation Nonverbal Reasoning Paper-and-Pencil Skill Perceptual Organization Sequential Processing Spatial Orientation Visual Motor Integration Secondary Abilities Shared With Other Subtests Perception of Abstract Stimuli Working Under Time Constraints Correlates of Subtest Performance Performance on the Mazes subtest may predict such specific behaviors as the examinee s ability to make, execute, and evaluate future plans; employ a reflective versus impulsive problem-solving style; concentrate and make sense of diffuse and confusing problems; make decisions after considering potential consequences; orient and organize one s environment spatially (e.g., follow directions, read maps, follow topographical outlines); apply a logical and sequential approach to solving problems; and work under time constraints.

24 220 Examiner s Manual UNIT Underlying Abilities and Exceptional Individuals In view of the literature on the patterns of psychometric performance among groups of exceptional children, examiners should anticipate differential performance among examinees on the various UNIT subtests. Unique clinical, cultural, and educational groups and their known characteristics in relation to UNIT performance are examined here. Attention-Deficit/Hyperactivity Disorder Attention deficit disorders (ADD) are characterized by the individual s inability to sustain attention, maintain concentration, ignore distractions, and inhibit impulsive behaviors. Attention deficit disorder with hyperactivity (ADHD) adds the element of extreme motor activity to the cognitive and behavioral characteristics. Although a commonly held belief is that ADD/ADHD negatively influences the intellectual functioning of individuals (Barkley, 1990), the consensus among ADD/ADHD studies is a finding of intellectual functioning in the average range (Carlson, Lahey, & Neeper, 1986; Schwean, Saklofske, Yackulic, & Quinn, 1993; Wechsler, 1991). In view of a consistent trend of an average range of intellectual functioning among examinees with ADD/ADHD and a less consistent trend of slightly better performance abilities than verbal abilities, examiners might anticipate that examinees with ADD/ADHD will typically earn UNIT FSIQs in the average range. The literature suggests that examinees with ADD/ADHD do less well on memory subtests than in other cognitive areas (McLaren & Paulson, 1995; Schwean et al., 1993; Wechsler, 1991). Memory subtests require considerable attention to detail, and examinees with ADD/ADHD are known to have deficits in this ability. The UNIT subtests were designed to include more salient stimulus characteristics to be attended to (e.g., number, location, color, figure/design, sequence); therefore, the UNIT memory subtests may prove especially difficult for examinees with ADD/ADHD. Naglieri, Das, and Jarman (1990) suggested that children with ADHD demonstrated average simultaneous abilities and deficits on tasks that assess attention, successive processing, and planning abilities. Thus, individuals with ADD/ADHD might be expected to do better on Cube Design, Spatial Memory, and Object Memory (simultaneous-processing tasks) than on Symbolic Memory and Analogic Reasoning (successive-processing tasks) and Mazes (planning). Because a sample with ADD/ADHD was not included in the UNIT validity studies, how these individuals will perform on the UNIT is a matter of conjecture. The literature suggests two viable hypotheses, which should be

25 Interpretation of UNIT Performance 221 tested in future research. In summary, as a group, examinees with ADD/ADHD would likely obtain FSIQs in the average range of intellectual abilities. Further, these examinees may reflect either a pattern of relatively stronger reasoning than memory abilities or relatively stronger simultaneous than successive or sequential abilities. Deafness and Hearing Impairments Deaf or hearing-impaired examinees should be expected to perform better on the UNIT than on traditional language-loaded intelligence tests. Because hearing-impaired examinees tend to perform better on performance tasks that invite active participation (Braden, 1994), their UNIT FSIQs may be higher than scores obtained on more narrowly defined tests that do not invite active participation. Discrepancies between scores on the UNIT Symbolic and Nonsymbolic scales may be related to differences in hearing-impaired examinees overall language abilities, even though no verbal reception or expression is required by the UNIT. In the studies reported in Chapter 6, deaf and hearing-impaired examinees scored an average of about one-third standard deviation lower than a normally hearing comparison group. Learning Disabilities As a group, individuals with learning disabilities generally obtain mean IQs in the average range, but those mean scores (i.e., 85 95) are frequently slightly below the population mean. The scores obtained by the examinees with learning disabilities and the comparison group, reported in Chapter 6, show this pattern. The examinees with learning disabilities earned a mean Standard FSIQ of compared to the mean FSIQ of earned by the comparison sample. Heterogeneous samples of examinees with learning disabilities often exhibit greater performance abilities than verbal abilities (Gresham & Reschly, 1986; Naglieri, 1985b; Wechsler, 1991), as do examinees who speak English as a second language, such as Hispanics (McShane & Cook, 1985). The UNIT, even more so than the WISC III (Wechsler, 1991) Performance Scale, appears to be less influenced by the verbal or quantitative deficits of examinees with learning disabilities than is a verbal scale. It is likely that the differential use of the UNIT and its nonverbal performance tasks for the assessment of Hispanic examinees intellectual functioning will result in more Hispanic examinees being identified as learning disabled and fewer misidentified as mentally retarded (MacMillan, Gresham, & Bocian, in press). Limited English Proficiency/ English as a Second Language Examinees with limited English proficiency (LEP) demonstrate higher intellectual abilities on performance scales than on verbal scales (MacMillan et al., in press; McShane & Cook, 1985); therefore, it is likely