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Psychological testing
Serials
Central nervous system
Psychological testing
M. Berger computed. Some summary measures o f group performance such as the average or percentages getting particular scores are determined and these constitute the test norms. Measurement is achieved by comparing the score o f an individual with the test norms - the score o f comparable individuals. If the child's score is above the average score for the group and if the child is o f the same chronological age as the group, then he or she is said to be of above average ability (on the tasks). If those tasks are thought to be manifestations o f intelligence, then it is argued that the child is o f above average intelligence, and so
A psychological test can be regarded as 'any systematic procedure for observing a person's behaviour and describing it with the aid of a numerical scale or category system 'x - - in essence, it is the apparatus and procedures employed for psychological measurement. The principles of psychological measurement are similar to those of other forms of measurement. The major differences that arise do so because many important psychological variables are not directly observable but, like intelligence, emotionality, sociability and the like are inferred from behaviour or performance. We observe individual differences in school achievement or in the propensity to become upset. These differences are hypothesised as being a consequence of individual differences in underlying characteristics such as intelligence or emotionality, respectively. Psychological tests are devices or procedures used to provoke the particular patterns of behaviour that are presumed (on various justifiable grounds) to be the external manifestations of the internal attributes or functions. 'Verbal ability', something not observable, is assumed to be provoked into showing itself by asking questions about the meanings of words, for example. The tasks used to provoke and capture the activity vary. They can be some activity to perform (complete a puzzle), questions to be answered by the individual, direct observations o f activity or indirect observation, such as questions to parent or teacher. A procedure is then devised to quantify or score the behaviour (counting the number of words properly defined, or the time taken to complete a geometric inset puzzle.) Once a procedure is worked out, the task is given to a suitably large group whose scores are then
on.
Test design and development - - psychometrics - are more sophisticated than implied above, having to take account o f such factors as there being no zero quantities for psychological variables and that for many attributes, the mere fact o f testing can change what is being measured: the child might learn to do the tasks that constitute the test in the process o f being tested. These and other.technical complexities have led to the development of special mathematical and statistical procedures to achieve measurement tools that yield reliable and meaningful scores. 2'3 Given that most if not all tests also derive from particular theoretical perspectives, it can be appreciated that psychological tests are somewhat more complex entities than might appear at first sight. A great variety o f such tests exit, to quantify intelligence, various aspects o f personality, educational attainment, neuropsychological function, language, and motor competence, among others. Further, for each domain different procedures are available, each intended to quantify the same characteristic. Hence, there are many different tests that purport to measure intelligence, others that aim to measure reading and so on. As measuring devices, psychological tests are not particularly difficult to administer. Indeed, nearly all
Michael Berger, Department of Clinical Psychology, (Child and Adolescent Section), Lanesborough Wing, St. George's ltospitat, London SWI7 OQT, UK Correspondence and requests for offprints to MB. (1991)I, 233-235 © 1991LongmanGroup UK Ltd
Current Vacdiatrics
233
234
CURRENT PAEDIATRICS
are accompanied by manuals that spell out in detail how to administer and score as well as interpret the test. Their systematic nature derives from the tight rules for administration and scoring. The challenge in psychological testing is thus not administration per se but rather the selection o f a n appropriate procedure that can answer a clinical question. This in turn requires an awareness of the adequacy o f the test as a test as well as an understanding of the limits of interpretation, which rest on a critical understanding o f the theory on which the test is based and its psychometric properties. Trained psychologists are therefore the people most likely to be in a position to select, administer and interpret these tests. It is helpful to distinguish between testing and assessment. The former is the administration and scoring o f the test, the latter is the bringing together o f a much broader range of information derived from variety o f sources in relation to a clinical problem with a view to advancing the understanding o f that problem and aiding its management and treatment. Testing is intended to contribute to rather than to constitute the assessment. The administration o f psychological tests, particularly to children, is not a favoured activity among those psychologists - - clinical and educational - most competent to use them. This is particularly unfortunate because childhood is the period in development when questions of the age appropriateness of many aspects of behaviour and functioning are of critical importance and properly used psychological tests can contribute,significant information to assessment. There is considerable evidence that functioning on such tests is a strong predictor of later functioning - - for instance, the IQ (Intelligence Quotient) in girls only within the second half of their first year is a good predictor of later functioning; that for all children the prediction o f later IQ is significantly improved after about two years o f age; and that infants scoring well below average are likely to show continued severe under functioning regardless of the reason for the low score. 4 There are many other good clinical reasons for using psychological tests as part o f the assessment process, 5 including contributing to differential diagnosis o f language disorders, establishment o f baseline functioning, the detection o f specific difficulties and indexing function in processes not tapped by other procedures. There are also many good reasons why psychologists are reluctant to use tests. In part this stems from difficulties in interprofessional relationships (other professionals seeing psychologists as simply people whose main contribution to clinical activity is to provide test"scores); concerns about the tendency for non-psychologists to overgeneralise test data; the inappropriateness o f some tests for certain social and ethnic groups as well as a misunderstanding by nonpsychologists o f the meanings o f test scores, particularly the IQ; and the sometimes limited relevance of tests to management and treatment. There may also
be an undercurrent of resentment because of the failure to recognise the increasingly wide role of clinical psychological assessment and treatment in complementing paediatric care, as evidenced by the advent of behaviourial paediatrics or child behaviourial medicine. 7 None of these arguments holds much strength if the psychologist has a good understanding of tests, their role in the assessment process, is able to take account of the strengths and weaknesses of a test for particular purposes, is sensitive to the behaviour of the child during testing and takes account of important social and ethnic constraints - - in sum, is properly educated in the use and interpretation of tests) Further, it is argued here that even if test data do no more than enhance understanding o f some aspects of a child's functioning, then that test has served a proper clinical purpose. It is up to paediatricians to make sure that they pose meaningful questions to psychologists or at least collaborate with psychologists to identify what the answerable questions are, and not simply ask for numbers (psychological tests are not like blood tests or the analysis of a urine specimen). What is important is not the numbers yielded by a blood test or psychological test but what the numbers mean. The expertise of physician and psychologist lies in the ability to provide a full interpretation of the numbers and to link these with the reasons for requesting the tests in the first place. Whatever the views of some individuals, the art and science o f psychological testing are flourishing, as witnessed by the regular updating o f common tests (such as the Revised version o f the Wechsler Preschool and Primary Scales of Intelligence 9) and books on testing, the appearance of new tests and books,'* and of special importance, the emergence of newer fields of applicatiofi, such as developmental neuropsychology. 1°
References I. Cronbach LJ. Essentials of psychologicaltesting, 3rd edn. New York,.Harper and Row, 1970. 2. Golden CJ, Sawicki RF, Franzen MD. Psychometric foundations. In GoldsteinG, and Hersen M. (Eds.) Handbook of psychologicalassessment, 2nd edn. New York, Pergamon Press 1990;21-40. 3. ReckaseMD. Scaling techniques. In Goldstein G, and Hersen M. (Eds.) Handbook of psychologicalassessment, 2nd edn. New York, Pergamon Press 1990;41-56. 4. CulbertsonJL, Gyurke J. Assessment of cognitiveand motor development in childhood. In Johnson JH and Goldman J. (Eds.) Developmentalassessment in clinical child psychology, New York, Pergamon Press 1990; 100-131. 5. BergerM, YuleW. IQ tests and assessment. In Clarke AM, Clarke ADB and BergJM (Eds.) Mental deficiency:the changing outlook, 4th edn. London, Methuen and Co. 1985; 53-98. 6. Perlman MD, Kaufman AS. Assessment of child intelligence. In Goldstein G, and Hersen M. (Eds.) tlandbook of psychologicalassessment, 2nd edn. New York, Pergamon Press 1990; 59-78. 7. FieldingD. Working with children and young people. In Marzillier,.IS and ttall J (Eds.) What is clinical psychology. Oxford, Oxford Medical Publications 1987;85-115. 8. BergerM. Towards an educated use of IQ tests: a reappraisal
PSYCHOLOGICAL TESTING of intelligence testing. In Lahey BB and Kazdin AE (Eds.) Advance in clinical child psychology, Vol. 9. New York, Plenum 1986; 1-33. 9. Wechsler D. Manual for the Wechsler preschool and primary scale of intelligence - - revised. New York, Psychological Corporation, 1989.
235
10. Taylor ttG, Fletcher JM. Neuropsychological assessment of children. In Goldstein G, and Hersen M. (Eds.) Handbook of psychological assessment, 2nd edn. New York, Pergamon Press 1990; 228-255.
Central nervous system
Psychological testing
M. Berger computed. Some summary measures o f group performance such as the average or percentages getting particular scores are determined and these constitute the test norms. Measurement is achieved by comparing the score o f an individual with the test norms - the score o f comparable individuals. If the child's score is above the average score for the group and if the child is o f the same chronological age as the group, then he or she is said to be of above average ability (on the tasks). If those tasks are thought to be manifestations o f intelligence, then it is argued that the child is o f above average intelligence, and so
A psychological test can be regarded as 'any systematic procedure for observing a person's behaviour and describing it with the aid of a numerical scale or category system 'x - - in essence, it is the apparatus and procedures employed for psychological measurement. The principles of psychological measurement are similar to those of other forms of measurement. The major differences that arise do so because many important psychological variables are not directly observable but, like intelligence, emotionality, sociability and the like are inferred from behaviour or performance. We observe individual differences in school achievement or in the propensity to become upset. These differences are hypothesised as being a consequence of individual differences in underlying characteristics such as intelligence or emotionality, respectively. Psychological tests are devices or procedures used to provoke the particular patterns of behaviour that are presumed (on various justifiable grounds) to be the external manifestations of the internal attributes or functions. 'Verbal ability', something not observable, is assumed to be provoked into showing itself by asking questions about the meanings of words, for example. The tasks used to provoke and capture the activity vary. They can be some activity to perform (complete a puzzle), questions to be answered by the individual, direct observations o f activity or indirect observation, such as questions to parent or teacher. A procedure is then devised to quantify or score the behaviour (counting the number of words properly defined, or the time taken to complete a geometric inset puzzle.) Once a procedure is worked out, the task is given to a suitably large group whose scores are then
on.
Test design and development - - psychometrics - are more sophisticated than implied above, having to take account o f such factors as there being no zero quantities for psychological variables and that for many attributes, the mere fact o f testing can change what is being measured: the child might learn to do the tasks that constitute the test in the process o f being tested. These and other.technical complexities have led to the development of special mathematical and statistical procedures to achieve measurement tools that yield reliable and meaningful scores. 2'3 Given that most if not all tests also derive from particular theoretical perspectives, it can be appreciated that psychological tests are somewhat more complex entities than might appear at first sight. A great variety o f such tests exit, to quantify intelligence, various aspects o f personality, educational attainment, neuropsychological function, language, and motor competence, among others. Further, for each domain different procedures are available, each intended to quantify the same characteristic. Hence, there are many different tests that purport to measure intelligence, others that aim to measure reading and so on. As measuring devices, psychological tests are not particularly difficult to administer. Indeed, nearly all
Michael Berger, Department of Clinical Psychology, (Child and Adolescent Section), Lanesborough Wing, St. George's ltospitat, London SWI7 OQT, UK Correspondence and requests for offprints to MB. (1991)I, 233-235 © 1991LongmanGroup UK Ltd
Current Vacdiatrics
233
234
CURRENT PAEDIATRICS
are accompanied by manuals that spell out in detail how to administer and score as well as interpret the test. Their systematic nature derives from the tight rules for administration and scoring. The challenge in psychological testing is thus not administration per se but rather the selection o f a n appropriate procedure that can answer a clinical question. This in turn requires an awareness of the adequacy o f the test as a test as well as an understanding of the limits of interpretation, which rest on a critical understanding o f the theory on which the test is based and its psychometric properties. Trained psychologists are therefore the people most likely to be in a position to select, administer and interpret these tests. It is helpful to distinguish between testing and assessment. The former is the administration and scoring o f the test, the latter is the bringing together o f a much broader range of information derived from variety o f sources in relation to a clinical problem with a view to advancing the understanding o f that problem and aiding its management and treatment. Testing is intended to contribute to rather than to constitute the assessment. The administration o f psychological tests, particularly to children, is not a favoured activity among those psychologists - - clinical and educational - most competent to use them. This is particularly unfortunate because childhood is the period in development when questions of the age appropriateness of many aspects of behaviour and functioning are of critical importance and properly used psychological tests can contribute,significant information to assessment. There is considerable evidence that functioning on such tests is a strong predictor of later functioning - - for instance, the IQ (Intelligence Quotient) in girls only within the second half of their first year is a good predictor of later functioning; that for all children the prediction o f later IQ is significantly improved after about two years o f age; and that infants scoring well below average are likely to show continued severe under functioning regardless of the reason for the low score. 4 There are many other good clinical reasons for using psychological tests as part o f the assessment process, 5 including contributing to differential diagnosis o f language disorders, establishment o f baseline functioning, the detection o f specific difficulties and indexing function in processes not tapped by other procedures. There are also many good reasons why psychologists are reluctant to use tests. In part this stems from difficulties in interprofessional relationships (other professionals seeing psychologists as simply people whose main contribution to clinical activity is to provide test"scores); concerns about the tendency for non-psychologists to overgeneralise test data; the inappropriateness o f some tests for certain social and ethnic groups as well as a misunderstanding by nonpsychologists o f the meanings o f test scores, particularly the IQ; and the sometimes limited relevance of tests to management and treatment. There may also
be an undercurrent of resentment because of the failure to recognise the increasingly wide role of clinical psychological assessment and treatment in complementing paediatric care, as evidenced by the advent of behaviourial paediatrics or child behaviourial medicine. 7 None of these arguments holds much strength if the psychologist has a good understanding of tests, their role in the assessment process, is able to take account of the strengths and weaknesses of a test for particular purposes, is sensitive to the behaviour of the child during testing and takes account of important social and ethnic constraints - - in sum, is properly educated in the use and interpretation of tests) Further, it is argued here that even if test data do no more than enhance understanding o f some aspects of a child's functioning, then that test has served a proper clinical purpose. It is up to paediatricians to make sure that they pose meaningful questions to psychologists or at least collaborate with psychologists to identify what the answerable questions are, and not simply ask for numbers (psychological tests are not like blood tests or the analysis of a urine specimen). What is important is not the numbers yielded by a blood test or psychological test but what the numbers mean. The expertise of physician and psychologist lies in the ability to provide a full interpretation of the numbers and to link these with the reasons for requesting the tests in the first place. Whatever the views of some individuals, the art and science o f psychological testing are flourishing, as witnessed by the regular updating o f common tests (such as the Revised version o f the Wechsler Preschool and Primary Scales of Intelligence 9) and books on testing, the appearance of new tests and books,'* and of special importance, the emergence of newer fields of applicatiofi, such as developmental neuropsychology. 1°
References I. Cronbach LJ. Essentials of psychologicaltesting, 3rd edn. New York,.Harper and Row, 1970. 2. Golden CJ, Sawicki RF, Franzen MD. Psychometric foundations. In GoldsteinG, and Hersen M. (Eds.) Handbook of psychologicalassessment, 2nd edn. New York, Pergamon Press 1990;21-40. 3. ReckaseMD. Scaling techniques. In Goldstein G, and Hersen M. (Eds.) Handbook of psychologicalassessment, 2nd edn. New York, Pergamon Press 1990;41-56. 4. CulbertsonJL, Gyurke J. Assessment of cognitiveand motor development in childhood. In Johnson JH and Goldman J. (Eds.) Developmentalassessment in clinical child psychology, New York, Pergamon Press 1990; 100-131. 5. BergerM, YuleW. IQ tests and assessment. In Clarke AM, Clarke ADB and BergJM (Eds.) Mental deficiency:the changing outlook, 4th edn. London, Methuen and Co. 1985; 53-98. 6. Perlman MD, Kaufman AS. Assessment of child intelligence. In Goldstein G, and Hersen M. (Eds.) tlandbook of psychologicalassessment, 2nd edn. New York, Pergamon Press 1990; 59-78. 7. FieldingD. Working with children and young people. In Marzillier,.IS and ttall J (Eds.) What is clinical psychology. Oxford, Oxford Medical Publications 1987;85-115. 8. BergerM. Towards an educated use of IQ tests: a reappraisal
PSYCHOLOGICAL TESTING of intelligence testing. In Lahey BB and Kazdin AE (Eds.) Advance in clinical child psychology, Vol. 9. New York, Plenum 1986; 1-33. 9. Wechsler D. Manual for the Wechsler preschool and primary scale of intelligence - - revised. New York, Psychological Corporation, 1989.
235
10. Taylor ttG, Fletcher JM. Neuropsychological assessment of children. In Goldstein G, and Hersen M. (Eds.) Handbook of psychological assessment, 2nd edn. New York, Pergamon Press 1990; 228-255.