THE RUFF 2 AND 7 SELECTIVE ATTENTION TEST: A NEUROPSYCHOLOGICAL APPLICATION 1

Perceptual and MotorSkills, 1992, 75, 1311-1319. Perceptual and Motor Skills 1992 THE RUFF 2 AND 7 SELECTIVE ATTENTION TEST: A NEUROPSYCHOLOGICAL APPLICATION 1 RONALD M. RUFF, HENDRlK NIEMANN, CHARLES C. ALLEN, CHARLES E. FARROW, THOMAS WYLIE School of Medicine University of California, San Diego Summary.-The neuropsychological application of the Ruff 2 and 7 Selective Attention Test as a measure of visual selective attention was investigated. The instrument was constructed as a paper-and-pencil approach to evaluate sustained attention utilizing different disrracror conditions in the study of voluntary or intentional aspects of attention. Four patient groups with cerebral lesions confined to either the right or left anterior or left or right posterior region (ns = 8, 8, 8, 6) were studied. Patients with right-hemispheric lesions showed a greater over-all reduction in processing speed independent of the serial or parallel processing mode in comparison to individuals with left-sided lesions. Furthermore, as predicted, the two groups with anterior brain damage showed a larger discrepancy berween serial and parallel processing modes than patients with posterior lesions. Specifically, the right frontal cases showed the greatest differential of accuracy on the serial and parallel tasks. The Ruff 2 and 7 Selective Attention Test, or the 2 and 7 Test, was developed with the aim of clinically assessing an individual's attentional capacity while (1) self-pacing target selection over a 5-min. period and (2) comparing different distractor conditions known to influence selection speed. (3) The test was designed for easy administration in a paper-and-pencil format to allow assessment at a patient's bedside without having to rely on the aid of computers, tachistoscope, etc. Within clinical settings, the most popular attention test administered is the Digit Symbol subtest from the WAIS-R, which has a proven sensitivity of capturing brain dysfunctioning (Wechsler, 1958). However, the duration is only 90 seconds, which limits the evaluation of prolonged sustained attention, i.e., 5 min. represents the lower time limit for evaluating monotonous processing (e.g., Broadbent, 1971; Parasuraman & Davies, 1984). Moreover, the Digit Symbol subtest evaluates, in addition to attention, the capacity for incidental learning, since the varying degrees of memorization of the nine symbols influence the speed of processing (Estes, 1974; Lezak, 1983). Thus, the Digit Symbol subtest or the subsequently developed Symbol-Digit Test (Smith, 1968) measure sustained attention in a limited and confounded manner. Having to select the numerical targets 2 and 7 does not represent a significant memory load, since even severely amnestic patients can retain two I Address requests for reprints to Ronald M. Ruff, Ph.D., Rehabilitation Center, St. Mary's Hospital and Medical Center, 450 Stanyan Street, San Francisco, CA 94117-1079.

1312 R. M. RUFF, ET AL. digits over prolonged periods without delay from interference (e.g., Lezak, 1983; Butters & Cermak, 1980). On the 2 and 7 Test, the subject is asked to cross out the digits 2 and 7 in two conditions. In one condition, the 2s and 7s are randomly interspersed among other digits, and in the second condition the distractors are made up of alphabetical letters. These two distractor conditions were selected on the basis of the experimental evidence put forth by numerous cognitive psychologists, claiming that the selection of targets among distractors from different stimulus categories (e.g., selecting digits from alphabetical letters) allows enhanced identification compared with selecting targets from the same stimulus category (e.g., selecting the digits 2 and 7 from other digits). Selecting targets from different stimulus categories has been described as representing a more parallel search or even an automatic in/ormation processing, while selecting targets from the same stimulus category is thought to require a more serial search or controlled in/ormation processing. The theory of serial and parallel processing initially proposed by Brand (1971) followed by Treisman (1982) as well as Schneider and Shiffrin's proposed distinction of controlled and automatic information processing (1977; Shiffrin & Schneider, 1977) are linked to specific experimental paradigms, e.g., tachistoscopic presentations. Thus, it is a leap for us to propose that these two modes of information processing also occur on the 2 and 7 Test, which is a paperand-pencil cancellation task. However, in a previous study, Ruff, Evans, and Light (1986) reported data which showed that normal adults were significantly slower in the digit-digit than digit-letter condition. Further evidence supporting the differential processing speeds was documented when monkeys were able to select out of a 3 x 3 array a single green diamond faster when the distractors were different colored shapes than when they were different green shapes (Bolster, Pribram, & Ruff, 1981). Thus, the differential for selecting targets faster among distractors from different vs same stimulus categories appears to be a robust finding. The purpose of this study was to explore the neuropsychological application of the 2 and 7 Test by cross-validating the earlier studies of Wilkins, Shallice, and McCarthy (1987) and Verfaellie, Bowers, and Heilman (1988) who indicated, when using different experimental tasks, that the right hemisphere was involved in voluntary or intentional aspects of attention. From this abstraction we hypothesized that patients with right-hemispheric lesions should show an over-all greater reduction in their processing rate irrespective of the processing condition than patients with left-hemispheric lesions, both groups matched against normals. In a second question, we explored whether the distinction between serial and parallel processing is diagnostically useful and whether deficits in either one can be related to lesions in different areas of the brain. Shallice

RUFF 2 AND 7 ATTENTION TEST 1313 (1982) proposed a model of planning with a similar distinction of two types of information processing and suggested that both types are monitored by different areas of the brain. According to Shallice, serial or controlled processing should be under the control of the frontal lobes whereas parallel processes are similar to skills or schemas which may be predominantly under control by posterior portions of the brain. We hypothesized then that patients with anterior lesions should show a larger discrepancy between the digit-letter and the digit-digit condition than patients with posterior lesions. METHOD Subjects A cohort of 30 patients were selected who satisfied the following criteria: (a) unilateral cerebral lesions were restricted to either the anterior region (involving portions of the frontal lobe) or to the posterior region (involving portions of the temporal, parietal, and occipital lobes). Agreement of three judges who reviewed CT-scans, neurosurgical, or neurological reports was required for inclusion of subjects in the lesion groups. (b) Also, right-handedness, (c) no motor deficits associated with peripheral damage, and (d) no history of hospitalization for psychiatric reasons were required. The selection process resulted in a sample of eight patients each with either right or left frontal lobe lesions and of six and eight patients with right and left posterior lesions, respectively. The reader not experienced with selecting patients with focal cerebral lesions should appreciate that great care was taken to select our patients out of hundreds of clinical cases examined over the years. No doubt a greater sample size would be desirable; however, this would require working with this population for additional years. if the above rigid selection criteria were utilized. Demographic data together with over-all levels of intellectual functioning and finger-tapping speed by the dominant hand are presented in Table 1. The latter was included to account for the possibility that differences on the 2 and 7 Test might have been due to motor speed. To provide a standard against which to compare the performance of the patients, a group of 60 normal subjects was selected from a larger standardization sample; for more information, see Baser and Ruff (1987). The normals were comparable to the patient group in terms of age (M = 31.2 yr., SD = 4.1) and education (M = 12.9 yr., SD = 1.5). Procedure The 2 and 7 Test requires the subject to cross out numerical targets as quickly as possible. The targets are embedded either in alphabetical capital letters (parallel processing) or in blocks of digits (serial processing). At first a sample of each block which consisted of three lines was presented to the patient to ensure that the instructions were understood; see

1314 R. M. RUFF, ET AL. TABLE 1 DEMOGRAPHIC AND SELECTED PSYCHOMETRIC CHARACTERISTICS OFLESIONED GROUPS Characteristic Lesioned Groups Right Anterior Left Anterior Right Posterior Left Posterior n,8 n, 8 n, 6 n, 8 Gender Male 7 5 4 5 Female 1 3 2 3 Age, yr. M 30.8 24.6 27.2 37.0 SD 6.2 5.1 11.2 14.0 Education, yr. M 13.9 12.8 13.0 15.1 SD 2.4 1.5 2.4 3.3 Full Scale IQ M 90.4 97.4 102.3 101.3 SD 20.0 13.5 9.9 12.8 Finger Tapping* M 42.1 4l.0 46.5 47.4 SD 5.3 14.2 9.8 7.8 Note.-The subtests of Wechsler Adult Intelligence Scale-Revised (Wechsler, 1981) were used to estimate the Full Scale IQ; the Finger-Tapping Test (Reitan & Davison, 1974) was employed to assess the fine motor speed of the hands. The one-way analyses of variance indicated only a trend for age (F326 = 2.38, p>.09); however, analyses for education, Full Scale IQ, and finger-tapping were nonsignificant. *Dominant hand. Fig. 1. If errors were made during the practice trial, the examiner emphasized the need for accuracy. The subject was told to begin the search from the top left side of the line and to proceed to the second and third lines in a similar fashion. After completion of the sample, the subject was instructed that in the main part of the test similar blocks would be presented. The subject was told that, after a brief period of time the examiner would say "Next," at which time the subject was to start a new block. Finally, speed of performance was again emphasized. The test comprises 20 blocks of three lines with a time limit of 15 sec. 2GOXC7MJ7HZRNGAS2YWQ2LHBZGJNV7ET2PRVMJ HSTQ2C7KLWC7XMT7KTR2AVPIWOC2GJ7LS2BNVW 7TQXR2PH7FDABM2WHKAST20PHWED2TRNEQX2PK 3 107 894 4 705 3 763 8 5 2 3 6 5 6 9 7 0 8 9 1 5 784 3 6 2 8 6 3 2 8 6 5 4 2 809 129 1 892 8 1 3 764 5 3 7 804 6 7 9 6 2 9 1 2 839 1 8 3 7 8 9 4 6 5 9 1 4 7 0 8 6 7 1 303 9 1 023 3 894 1 265 5 FIG. 1. or digits) The 2 and 7 Test (note that sample blocks of targets are embedded in either letters

RUFF 2 AND 7 ATTENTION TEST 1315 per block. The sequence of distractors is as follows (D =digits; L =letters): D, L, L, D, D, L, D, L, L, D, D, L, D, L, L, D, L, D, L, D. The blocks are printed on two 8lf2 - x ll-in. pages which are taped together on the back sides. Each line contains 10 target and 40 distractor stimuli. The distance between target and dis tractors is equal. The target location is randomized throughout each line. To score the test the total number of hits and errors (i.e., omissions and commissions) were computed separately for each distractor condition. For the purpose of the present study the following scores were used: (1) Speed: sum of hits "digit-letter" (DL) and hits "digit-digit" (DD), (2) Accuracy: (total hits DL and DD) - (total errors DL and DD) ------------~-- --~ ---------- xloo (total hits DL and DD) From these scores two ratios were computed to investigate differential effects of the two distractor conditions: (a) Processing 1: (b) Processing 2: (total hits DL) (total hits DD) (hits DL - errors DL)j(hits DL) (hits DD - errors DD)/(hits DD) Hypotheses and Statistical Analysis Hypothesis 1.-If the right hemisphere is involved in intentional or voluntary aspects of attention, then patients with right-sided lesions should show a lower mean processing rate on the 2 and 7 Test irrespective of the distractor condition than individuals with left-sided lesions. No differences should be observed along the anterior-posterior dimension of brain lesions, and the interaction between the two factors should be nonsignificant. A 2 x 2 analysis of variance was computed with the Speed score as the dependent variable. In addition, the Accuracy score was subjected to a similar analysis; it was expected that voluntary aspects of attention would not affect the accuracy of the performance. Hypothesis 2.-If the frontal portions of the brain monitor serial processing and the posterior areas of the brain are involved in parallel processing, then the performance on the 2 and 7 Test of patients with frontal lesions should differ from those with posterior lesions. The former group of patients should have a larger ratio (Letter condition/digit condition) than the latter group. No differences should be observed according to the side of lesion, and the interaction between the laterality and the anterior-posterior factor should be nonsignificant. We tested this hypothesis by computing a 2 x 2 analysis of variance. Both ratio scores were employed as dependent variables,

1316 R. M. RUFF, ET AL. since it was unclear whether the brain lesions would affect speed or accuracy of performance under serial and parallel processing conditions. Hypothesis 1 RESULTS Patients with right-sided lesions performed on the 2 and 7 Test at a significantly lower processing rate (Speed score) than patients with left-sided lesions (F I 26 = 10.96, P<.005), thereby supporting the first hypothesis; see Table 2. As predicted, the location of the lesion along the anterior-posterior dimension was without influence (F I 26 = 1.87) as was the interaction (F,. 26 =.10). Surprisingly, not only the processing rate but also the accuracy was affected by the location of the lesion; see Table 2. For the Accuracy score a trend was obtained for both laterality (F,. 26 =2.92, p<.10) and the interaction term (FI 26 = 3.52, P<.08). Patients with right anterior lesions performed the least accurately, whereas the left anterior group obtained a mean score similar to that of the normal subjects. Posterior lesioned groups maintained a middle position and did not differ from each other. TABLE 2 MEANS AND STANDARD DEVIATIONS OF SPEED AND ACCURACY SCORES ON THE RUFF 2 AND 7 TEST FOR LESIONED GROUPS AND NORMALS Groups n Speed Accuracy M SD M SD Right Hemisphere Anterior 8 176.0 47.9 79.5 15.6 Posterior 6 204.7 43.8 90.0 5.0 Left Hemisphere Anterior 8 236.4 54.4 94.2 3.5 Posterior 8 254.3 33.3 88.6 15.0 Normal 60 284.4 47.2 94.4 4.7 Hypothesis 2 The results of the analysis of variance for the Processing 1 score did not support the hypothesis that anterior lesions would differentially affect the speed of serial processing, thereby increasing the ratio between parallel and serial processing for this patient group (F,. 26 =.02). As expected the laterality factor (F,. 26 =.03) and the interaction term (F I. 26 =.01) were nonsignificant. In contrast, a trend was found for the Processing 2 score. Patients with anterior lesions showed a larger discrepancy in their accuracy under the two processing conditions than patients with posterior lesions (F I 26 = 2.88, P<.10). The mean ratio for the latter patient group was comparable to that for the normal subjects; see Table 3. As expected, the right-left differences (F ' 26 <.01) and the interaction (F,. 26 =.003) were nonsignificant..

RUFF 2 AND 7 ATTENTION TEST 1317 TABLE 3 MEANS AND STANDARD DEVIATIONS OF PROCESSING 2 SCORES ON THE RUFF 2 AND 7 TEST FOR LESIONED GROUPS AND NORMALS Groups n Processing 2 M SD Anterior Right 8 1.09.13 Left 8 1.08.08 Posterior Right 6 1.02.03 Left 8 1.04.05 Normal 60 1.04.04 DISCUSSION The present study supports the neuropsychological application of the 2 and 7 Test. According to this simple paper-and-pencil measure, our investigation showed that patients with right-sided lesions performed at a significantly reduced processing rate relative to patients with left-sided lesions. This finding is consistent with the experimental findings of Wilkins, et al. (1987) and Verfaellie, et at. (1988) who reported that right-sided brain lesions tended to affect voluntary or intentional aspects of attention. Moreover, the findings are not confounded by reduced motor speed. On one hand, the lesioned groups did not differ in their finger-tapping speed (pure motor speed measure) with the dominant hand, and on the other hand, it is unlikely that a lesion in the right hemisphere would affect fine motor speed or coordination of the ipsilateral or dominant hand. Individuals with right-frontal lesions not only worked more slowly but also less accurately than the other patient groups. Although all patient groups performed more slowly than the normal subjects, the left-frontal lesioned patients were as accurate as the normal subjects. The two distractor conditions within the test allow a potentially interesting distinction. According to the literature, automatic or parallel information processing is faster and relatively effortless, whereas controlled or serial information processing is slower and more effortful. However, the underlying brain mechanism in these two attentional processes is poorly understood. Shallice (1982) has argued that controlled processing is primarily monitored by the frontal portions of the brain and the posterior regions of the cortex are involved in the automatic processing of information. In the present study, we made a first attempt in evaluating the clinical usefulness of this concept with a paper-and-pencil test. It was predicted that patients with anterior lesions would show a deficit in controlled processing, thereby increasing the ratio between the two processing modes. Of two scores only one (ratio of accuracy) showed a trend in the predicted direction. A number of factors may be related to this result. The patient sample included different

1318 R. M. RUFF, ET AL. etiologies, and the sample sizes were quite small. In spite of these limitations, an alternative explanation may be pertinent for both conditions: if visual-search strategies are inefficient, frontal lesions may interfere with automatic processes by making them become more controlled and thereby reduce the processing rate by the same amount. In summary, the Ruff 2 and 7 Selective Attention Test is an easily administered instrument which not only assesses deficits in speed and accuracy of information processing but also is shown to be sensitive to differential neuropathology. Further neuropsychological application seems appropriate. Since our first publication (Ruff, et al., 1986), we have normed this test on 360 adults stratified by age, gender, and education, and 100 subjects have been retested to establish its reliability. Some applications have begun, since the test has been shown sensitive to early detection of AIDS (Schmitt, Bigley, McKinnis, Logue, Evans, Drucker, & the AZT Collaborative Working Group, 1988). The 2 and 7 Test was also used with the Traumatic Brain Injury Data Bank (Levin, Gary, Eisenberg, Ruff, Barth, Kreutzer, High, Portman, Foulkes, Jane, Marmarou, & Marshall, 1990), and particularly the speed score was one of the key predictors of returning to work or school (Ruff, Marshall, Crouch, Klauber, Levin, Barth, Kreutzer, Eisenberg, Jane, Marmarou, & Foulkes, in press). REFERENCES BASER, C. A., & RUFF, R. M. (1987) Construct validity of the San Diego Neuropsychological Test Battery. Archives of Clinical Neuropsychology, 2(1), 13-32. BOLSTER, R. B.. PRIBRAM, K. H., & RUFF, R. M. (1981) Visual search in the monkey: transcortical potentials evoked by feature conjunctions. Presented to the International Neuropsychologrcal Society Meeting, Atlanta, GA, 1980. BRAND, J. (197l) Classification without identification in visual search. Quarterly Journal of Experimental Psychology, 23, 178-186. BROADBENT, D. E. (1971) Decision and stress. London: Academic Press. BU'ITERS, N., & CERMAK, L. S. (1980) Alcoholic Korsakoff's syndrome: an information processing approach to amnesia. New York: Academic Press. ESTES, W. K. (1974) Learning theory and intelligence. American Psychologist, 29, 740-749. LEVIN, H. S., GARY, H. E., JR., EISENBERG, H. M., RUFF, R. M., BARTH, J. T., KREUTZER,]., HIGH, W. H., JR., PORTMAN, S., FOULKES, M. A., JANE, ]. A., MARMAROU, A., & MARSHALL, L. F. (1990) Neurobehavioral outcome one year after severe head injury: experience of the Traumatic Coma Data Bank. Journal ofneurosurgery, 73, 699-709. LEZAK, M. D. (1983) Neuropsychological assessment. (2nd ed.) New York: Oxford Univer. Press. PARASURAMAN, R., & DAVIES, D. R. (1984) Sustained attention in detection and discrimination. In R. Parasurarnan & D. R. Davies (Eds.), Varieties of attention. Orlando, FL: Academic Press. Pp, 243-271. REITAN, R. M., & DAVISON, L. A. (Eds.) (1974) Clinical neuropsychology: current status and applications. New York: Winston-Wiley. RUFF, R. M., EVANS, R. W., & LIGHT, R. H. (1986) Automatic detection vs controlled search: a paper-and-pencil approach. Perceptual and Motor Skills, 62, 407-416. RUFF, R. M., MARSHALL, L. F., CROUCH, J. A., KLAUBER, M. R., LEVIN, H. S., BARTH, J. T., KREUTZER, J., EISENBERG, H. M., JANE, J. A., MARMAROU, A., & FOULKES, M. A. (1992) Predictors of outcome following severe head trauma: follow-up data from the Traumatic Coma Data Bank. Brain Injury, in press. SCHMITI, F. A., BIGLEY, J. W., McKINNIS, R., LoGUE, P. E., EVANS, R. W., DRUCKER, J. L., &

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