Perceptual and Motor Skills, 2004,98,840-848. O Perceptual and Motor Skills 2004
CORSI'S BLOCK-TAPPING TASK: STANDARDIZATION AND LOCATION IN FACTOR SPACE WITH THE WAIS-R FOR TWO NORMAL SAMPLES O F OLDER ADULTS ' ARISTIDE SAGGINO, MICHELA BALSAMO, ANNA GRIECO, MARIA ROSARIA CERBONE, AND NICLA NICOLINA RAVIELE Universitd' degli Studi "G. d'AnnunzioJJ di Chieti-Pescara Summay.-Corsi's block-tapping task and WAIS-R were administered to two Italian samples of 200 normal older adults (aged 65-74 years and 75-100 years). Corsi's reliabilities and standardization data are shown. Additionally, Corsi's location in the factor space of cognitive abilities represented by the 11 WAIS-R subtests is presented. Corsi's test seems to be a reliable one for older Italians. It seems also to be a measure of general intelligence in those 65-74 years of age and a measure of the Freedom from Distractibility factor in subjects 75 years and older.
The Corsi's block-tapping task (Corsi, 1972) is one of the most important nonverbal tests used in neuropsychological research and in the assessment of spatial memory of brain-damaged patients. Corsi (1972) developed the block-tapping task as a spatial alternative to procedures assessing memory for verbal sequences, as represented by the digit span task. At present, this task is usually included as a component of a major neuropsychological battery and has recently been adapted to a number of computerized formats (Berch, Krikorian ,& Huha, 1998). The age range to which it has been applied extends from children to older adults. Clinical populations studied to date have included Korsakoff's and Alzheimer's patients, the mentally retarded, learning-disabled children, and those with other neurological disorders (Berch, et al., 1998). The Corsi's block-tapping task has been used for a variety of purposes: to assess deficits in short-term nonverbal memory (De Renzi, Faglioni, & Previdi, 1977, cit. by Berch, et al., 1998), to investigate sex differences (Orsini, Grossi, Capitani, Laiacona, Papagno, & Vallar, 1987; Capitani, Laiacona, Ciceri, & Gruppo Italiano per lo Studio Neuropsicologico dell'Invecchiamento, 1991), to clarify theoretical conceptions of visuospatial memory (Berch, et al., 1998). Orsini, et al. (1987) demonstrated that visuospatial immediate memory span, which is about four items in a normal subject, declines after the late 'The authors ratefull acknowledge the comments and the suggestions of Professor Arthur R. Jensen on earfer draXs of this article. This research was in part presented with some differences at the A.I.A.M.C. XI Congress, Palermo, Italy, 3-6 October 2001 and at the AIP Experimental Psychology Congress, Bari, Italy, 22-25 October, 2003. Address correspondence to A. Saggino, Universith "G. d'AnnunzioV di Chieti-Pescara, Facolth di Psicologia, Via dei Vestini66100 Chieti, Italy or e-mail (
[email protected]).
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sixties and is affected by age, education, and sex differences, with male subjects scoring better. They also presented normative data both for normal Italian children and adults. They used a different administration and scoring procedure. The Corsi's score (spatial span score) was represented by the longest sequence the subject correctly recalled on three out of five trials. Similar results were obtained by Orsini, Chiacchio, Cinque, Cocchiaro, Schiappa, and Grossi (1986). According to Berch, et al. (1998), Corsi's test has been used in research with different administration procedures and display characteristics. Furthermore, only a few studies have provided norms for the test. Therefore, Berch, et al. (1998) maintain that it is essential to establish definite display and administration procedures and collect normative data on different populations. The aims of the present paper were the following: first, to provide Corsi's preliminary normative data on normal older Italian adults (aged 65-74 and 75-100 years); second, to study validity of Corsi's test across location in the factor space of cognitive abilities as identified by the 11 subtests of the Wechsler Adult Intelligence Scale-Revised ( WAIS-R; Wechsler , 1981). Moreover, reliabilities of Corsi's test and its relationships with sociodemographic variables were investigated. Subjects The Italian edition of the WAIS-R and the Corsi's block-tapping test were administered to two Italian samples of 200 volunteer normal, healthy older adults (65-74 years and 75-100 years). The mean age of the sample ages 65-74 years (n =200) was 68.9 yr. (SD=2.7). The mean age for the women (n = 105) was 68.9 yr. (SD= 2.6); for the men (n = 95) the mean age was 68.8 yr. (SD=2.7). The mean years of education for this sample was 5.8 yr. (SD = 3.1). The mean years of education was 5.0 yr. (SD = 3.1) for the women and 6.7 yr. (SD = 2.8) for the men. The mean age of the sample over 74 years (n = 200) was 78.4 yr. (SD = 4.5). The mean age was 78.0 yr. (SD=4.2) for the women (n = 114) and 78.8 yr. (SD = 5 .O) for the men (n = 86). The mean years of education for this sample was 5.9 yr. (SD = 3.7). It was 5.5 yr. (SD= 3.4) for the women and 6.4 yr. (SD=4.0) for the men. The two samples consisted of pensioners and housewives and part of the data (n = 200) was utilized in a previous paper to study the psychometric aspects of the WAIS-R in older age groups (Saggino, Balsamo, & Grieco, 1999). All subjects were free of neurological, psychiatric, or sensory disabilities. Information was requested on current or past illnesses with the aim of excluding people with neurological disorders, psychiatric histories, and alcohol or drug use.
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Procedure Subjects were administered the 11 subtests of the WAIS-R and immediately afterwards Corsi's block-tapping test. Some of them (104 for the sample 65-74 years of age and 99 for the sample over 74 years of age) were given a retest of WAIS-R Digit Span and Digit Symbol subtests and Corsi's block-tapping task within 15 days to study their reliabilities. Other tests not considered in the present paper were also administered. Some of the data regarding the WAIS-R scale were discussed in Saggino, et al. (1999). Other data, relating the WAIS-R to the NEO Personality Inventory Revised (NEO-PI-R; Costa & McCrae, 1992) were discussed by Saggino and Balsamo (2003). The Corsi's test measures visuospatial short-term memory. In this task, nine identical small white cubes (side 4 cm) are arranged irregularly over a wooden board (26 x 32 cm). The sides of the cubes facing the examiner are numbered from 1 to 9 to ease administering the task and recording performance. The examiner taps some of the blocks (digits) in a particular sequence; the subject is required to tap out exactly the same pattern immediately afterwards. The examiner taps the blocks one at a time using the index finger at the rate of 1 block per 2 sec. The test begins with a sequence of two units and, if the subject succeeds, increasingly long sequences are presented. Each time a maximum of five equal-unit sequences is tapped out. The test ends when a subject reproduces five sequences of the same length incorrectly. The sequences used are from 2 to 9 digits for a total of 40 items (Orsini, et al., 1987). Corsi's test score is the number of items correctly reproduced. The test scoring, the display procedures, and the administration of the test are the same as those used by Orsini (1994). These administration and scoring procedures were selected because they are more similar and comparable to those used with the Digit Span WAIS-R subtest. The sum of the raw scores of the corresponding WAIS-R subtests was used as an estimate of the Verbal, Performance, and Full Scale IQs because there is at the moment no Italian standardization of the WAIS-R for subjects over 65 years of age. Therefore, we used the sum of the six verbal subtests' raw scores to obtain the Verbal Intelligence score, the sum of the five performance subtests' raw scores to obtain the Performance Intelligence score, and the sum of all the 11 subtests' raw scores to obtain the Full Scale Intelligence score. For purpose of comparisons, we calculated the correlations between these three scores and the corresponding three sums of the WAIS-R scaled scores based on the age group of 19-34 years in a subgroup of 100 subjects over 74 years old (Saggino & Balsamo, 2003). We obtained correlations higher than .90, indicating that the two scores can be considered substantially equivalent.
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RESULTS AND DISCUSSION The mean for raw scores on Corsi's test was 15.7 (SD = 3.9) for the sample of age 65-74 years, with a mean of 14.3 (SD = 3.5) for the female sample and 17.3 (SD =3.7) for the male sample. The mean of raw scores for Corsi's test is 14.1 (SD =3.3) for the sample over 74 years of age, with a mean of 13.5 (SD = 3.5) for the female sample and 14.9 (SD= 3.0) for the male sample. The standard error of measurement corresponds to 4.6 for the sample 65-74 years of age (4.2 for the women and 4.5 for the men) and to 4.4 for the sample over 74 years of age (4.7 for the women and 4.0 for the men). All statistical analyses of the present paper were computed on raw scores. Multiple regression analyses were calculated using sex, age, and years of education as predictors of Corsi's block-tapping test scores. In the group 65-74 years of age, all three variables collectively accounted for 18% of the score variance (adjusted R2= .18; F,,,,, = 15.52, p < .0005). Only years of education (beta = .216, t = 3.2 1, p < .005) and sex (beta = 324, t = 4.85, p < .0005) accounted for a significant amount of unique explained variance in Corsi's block-tapping test scores. In the sample over 74 years of age, the three variables collectively accounted for 19% of the score variance (adjusted R2= .19; F,,,,,= 16.37, p < .0005). All three predictors accounted for a significant amount of unique explained variance in the block-tapping test scores: years of education (beta = 339, t = 5.27, p < .0005), age (beta = - 201, t = -3.13, p < .OO5), and sex (beta = .185, t = 2.86, p < .01). Therefore, sex and education (and, to a lesser extent, age) represent important predictors of the Corsi test scores, as they are in general for all the variables of the cognitive domain (Orsini, et al., 1986, 1987; Jensen, 1998). Reliability of Corsi's test was calculated using both the split-half method (with correction by the Spearman-Brown formula) and the test-retest method. Split-half reliability was .86, and test-retest reliability was .85 for the sample 65-74 years of age. Split-half reliability was .85 and test-retest reliability was .75 for the sample 74 years and over. Therefore, Corsi's blocktapping test shows for normal older adults a good reliability (both internal consistency and temporal stability). The corresponding reliabilities for the WAIS-R subtests can be found in Saggino, et al. (1999). Table 1 shows the conversion of raw scores for Corsi's test to scaled standard scores (M= 10, SD = 3) to allow comparison between scores obtained by subjects given Corsi's test and WAIS-R subtests. In fact, unlike raw scores, scaled scores allow comparison of results obtained on different tests. It facilitates the possible use of Corsi's test as a twelfth WAIS-R subtest. Table 2 shows correlations for Corsi's test scores with those on the WAIS-R subtests and the three WAIS-R total scores (Verbal, Performance, and Full Scale). We present both the zero-order correlations and the partial correlation coefficients to control sex, age, and years of education because
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TABLE 1 SCALED STANDARD SCORES FORCORSI'STESTEQUIVALENT TO RAW SCORES (ns = 200) Scaled Standard Score
I 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Raw Score Equivalent 65-74 yr. 75-100 yr.
3
2
4 7-8 9-10 11 12 13 14 15-16 17 18-19 20 21 22 23-24 25
3-4 5-6 7-8 9-10 11-12 13 14 15 16 17 18 19 20 21
27
Scaled Standard Score
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
these three variables notoriously influence scores on cognitive tests, as we have already demonstrated (see also Orsini, et al., 1986, 1987). For the group 65-74 years of age, salient partial correlation coefficients TABLE 2 ZERO-ORDER CORRELATIONS AND PARTIAL CORRELATIONS OF CORSI'S TESTSCORES AND TOTAL SCORES (ns = 200) WITHWAIS-R SUBTEST WAIS-R Subscale and Total Scale
Y
65-74 Years Partial r"
Information .40 .23 Digit Span .40 .28 Vocabulary 34 .2 1 Arithmetic .44 .29 Comprehension .38 .24 Similarities .3 1 .20 Picture Completion .38 .22 Picture Arrangement .27 .18 Block Design .42 .32 Object Assembly 39 .28 Digit Symbol .40 .26 Verbal Scale Score .42 .30 Performance Scale Score .47 36 Full Scale Score .47 .37 "Partial correlations with sex, age, and education controlled.
r
75-100 Years Partial r"
38 .47 .4 1 .44 .36 .30 32 .35 .26 .18 .36 .47 35 .45
.15 .36 .2 1 .27 .15 .10 .12 .21 .07 .OO .16 .26 .12 .22
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for Corsi's test scores (that is, all the absolute correlations equal to or greater than 3 0 ) were with WAIS-R Full Scale (.37), Performance (.36), and Verbal scale scores (.30) and for WAIS-R Block Design (32). For the sample over 74 years of age, the only salient partial correlation coefficient for Corsi's test was with the WAIS-R Digit Span (.36). All the zero-order correlations were greater than 3 0 , with the only exception of Picture Arrangement (.27) in the sample 65-74 years of age; in the sample over 74 years of age, Block Design (.26) and Object Assembly (.18) were the only exceptions. To obtain more precise information on Corsi's test validity for older adults, we located the Corsi's block-tapping task in cognitive factor space as represented by the 11 WAIS-R subtests. Thus, the intercorrelations of these 12 variables for each age group were subjected in an initial run, following Kaufman (1975) and Orsini (1994)' to a principal components analysis to estimate the number of factors. Two criteria were used to obtain the number of factors to extract: the scree plot (Cattell, 1966) and the Kaiser's roots > 1.00 criterion. Then a principal factor analysis was performed. We preferred the principal factor analysis method because it is considered more adequate in research on the g factor and cognitive abilities (Jensen, 1998). A one-factor solution emerges by the Scree test for the sample 65-74 years of age. Furthermore, the initial eigenvalue of the first principal component is 6.72, while the initial eigenvalue of the second principal component is .998. Therefore, a one-factor principal axis solution was selected. The principal axis factoring solution explains 52.3% of the total variance. All the 12 variables present loadings higher than .50, as shown in Table 3. The Corsi's test has a loading of .>I. Therefore, this factor represents the g factor, or general intelligence. In this sample Corsi's test seems to be a good measure of the g factor. TABLE 3 UNROTATED FIRSTPRINCIPAL FACTOR LOADINGS FORTHE SAMPLE 65-74 YEARSOF AGE(n = 200) Subscale WAIS-R Information Digit Span Vocabulary Arithmetic Comprehension Similarities Picture Completion Picture Arrangement Block Design Object Assembly Digit Symbol Corsi's Test
Loading
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For the sample over 74 years of age, a three-factor solution emerges by the scree test. The initial eigenvalues of the principal components solution correspond to 6.01 for the first component, 1.13 for the second component, and 1.01 for the third component. The fourth component has an eigenvalue corresponding to .72. For this reason, only three factors were selected by the principal axis factoring method and rotated by the oblique direct oblimin method, which represents a choice better than the varimax when the factors are correlated (correlations range from .48 to .65). This solution explains 58.4% of the total variance after extraction. After this initial run we preferred a Schmid and Leiman hierarchical factor analysis as the definitive choice because it divides the variance of the variables into that due to unique variance (primary factors) and that due to the common variance (secondary factors). The hierarchical factor analysis is considered particularly useful when one is interested in studying the variables at different hierarchical levels because the interpretation of the second-order factors are based on the original variables and not on the interpretations of the first-order factors, as happens when we perform a first-order factor analysis followed by a secondorder factor analysis. We obtained three primary and one secondary factor, as shown in Table 4. The first primary factor represents mainly the Verbal Comprehension factor. In fact, four out of the six verbal subtests (CompreTABLE 4 SCHMIDAND LEIMAN HIERARCHICAL FACTOR ANALYSIS LOADINGS OF WAIS-R ELEVEN SUBTESTS AND CORSI'STESTFORTHE SAMPLE OVER74 YEARSOF AGE(n = 200) Subscale
Secondary Factor 1
Factor 1
Primary Factor 2
Factor 3
WAIS-R Information Digit Span Vocabulary Arithmetic Comprehension Similarities Picture Completion Picture Arrangement Block Design Object Assembly Digit Symbol Corsi's Test
hension, Similarities, Information, and Vocabulary) have their salient loadings (that is, absolute loadings equal to or higher than .3O) on the primary Factor 1. Also, two performance subtests (Picture Completion and DigitSymbol) have their salient loadings on this factor. Therefore, it does not seem to be a pure Verbal Comprehension factor. Factor 2 has its salient
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loadings on two performance subtests (Block Design and Object Assembly). Therefore, it appears to correspond to the Perceptual Organization factor, even if only two subtests from the Performance scale have their salient loadings on this factor. Factor 3 has its highest loadings on Digit Span, Arithmetic, and Corsi's block-tapping test so it seems to be the usual Freedom from Distractibility factor. In this sample, Corsi's test has its lowest loading on the Verbal Comprehension factor and its highest loading on the Freedom from Distractibility factor, as was found for children ages 11 to 16 years by Orsini (1994). As regards the secondary factor, both the 11 WAIS-R subtests and the Corsi's test have loadings greater than .50 on this factor. Therefore, it seems to be the usual g factor. In conclusion, Corsi's test seems to be reliable for use with older normal Italian adults. As regards its validity, it loaded substantially on the WAIS-R g factor for adults 65-74 years old. In older subjects (over 74 years) it seems to measure particularly the Freedom from Distractibility factor together with the Digit Span and Arithmetic WAIS-R subtests at a primary level. At the secondary level, it loads on the general intelligence factor together with all the 11 WAIS-R subtests. Therefore, in the older sample, the Corsi's block-tapping test is largely a measure of short-term memory, loading on the same primary factor as the Digit Span subtest. Our results seem to confirm the recent view that verbal and spatial short-term memory are not independent (Jones, Farrand, Stuart, & Morris, 1995, cit. by Berch, et al., 1998). However, these preliminary findings stdl need to be confirmed in independent and, preferably, larger and more varied samples. In particular, the differences in the factor structure we have found in the two different age groups should be studied further. REFERENCES BERCH,D. B., KRIKORIAN, R., & HUHA,E. M. (1998) The Corsi Block-tapping Task: methodological and theoretical considerations. Brain and Cognition, 38, 317-338. CAPITANI, E., LAIACONA, M., CICERI,E., & GRUPPOITALIANO PER LO STUDIONEUROPSICOLOGICO DELL'INVECCHIAMENTO. (1991) Sex differences in spatial memory: a reanalysis of block tapping long-term memory according to the short-term memory level. The Italian lournal of Neurological Sciences, 12, 461-466. CATTELL, R. B. (1966) The scree test for the number of factors. Multivariate Behavioural Research, 1, 141-161. CORSI,l? M. (1972) Human memory and the medial temporal region of the brain. Dissertation Abstracts International, 34, 891B. COSTA,l? T., JR., &MCCRAE,R. R. (1992) Revised NEO Personality Inventory (NEO-PI-R) and NEO Five-Factor (NEO-FFI) professional manual. Odessa, FL: Psychological Assessment Resources. DE RENZI,E., FAGLIONI, P, &PREVIDI,l? (1977) Spatial memory and hemispheric locus of lesion. Cortex, 13, 424-433. JENSEN, A. R. (1998) The g factor: the science of mental ability. Westport, CT: Praeger. JONES,D., FARRAND, l?, STUART, G., &MORRIS,N. (1995) Functional equivalence of verbal and spatial information in serial short-term memory. Journal of Experimental Psychology: Leavning, Memory, and Cognition, 21, 1008-1018.
