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Verbal rehearsal and selective attention in children with learning disabilities: A developmental lag
JOURNAL
OF EXPERIMENTAL
CHILD
PSYCHOLOGY
22, 375-385 (1976)
Verbal Rehearsal and Selective Attention in Children with Learning Disabilities: A Developmental Lag SARA G. TARVER',DANIEL P. HALLAHAN*,JAMES AND DONALD W. BALL* Universiiy
of Wisconsin,’
and
University
M. KAUFFMAN*,
of Virginia’
To investigate the development of verbal rehearsal strategies and selective attention in learning disabled children, Hagen’s Central-Incidental task was administered to younger learnink disabled (M CA = 8.68 years) and normal (M CA = 8.62 years) boys in Experiment I and to intermediate (M CA = 10.18 years) and older (M CA = 13.48 years) learning disabled boys in Experiment 2. Also, in Experiment 2, an experimentally induced verbal rehearsal condition was included to determine its effects on serial recall and selective attention performance. In Experiment 1, the serial position curve of the normals revealed both a primacy and a recency effect, whereas that of the learning disabled revealed a recency effect only. In Experiment 2, both the intermediate and the older learning disabled exhibited both primacy and recency effects under both standard and rehearsal conditions. A developmental analysis of central recall for the three learning disabled groups revealed constant age-related increases in overall central recall and in primacy recall. That the normals recalled more central, but not more incidental, information than the learning disabled in Experiment 1 suggests that the learning disabled are deficient in selective attention. Correlational findings suggest that the selective attention of the learning disabled improves with age. The results were interpreted as support for the hypothesis of a developmental lag in the learning disabled population.
Age-related increases in serial recall in normal children have been found to reflect a series of changes in verbal encoding strategies and selective attention. Verbal encoding strategies become increasingly efficient with age, progressing from simple verbal labeling strategies employed prior to the age of 8 years to more efficient cumulative verbal rehearsal strategies by the age of 10 years (Hagen, 1971) and then to strategies including labeling, cumulative rehearsal, and chunking by the age of about 11 years (McCarver, 1972). Improvements in selective attention performance, as evidenced by a decline in incidental relative to central recall and /or a shift from a positive to a negative correlation between incidental and central Experiment 2 of this report is based on the doctoral dissertation of the senior author submitted in partial fulfillment of the requirements for the Ph.D. degree at the University of Virginia. The authors are indebted to Jean N. Dickinson (University of Richmond), Richard A. Bell (The Stony Point School), Mary Louise Trusdell (The New Community School), and John B. Finkler (Chesterfield County Public Schools). Reprints are available from Dr. Sara Tarver, Department of Studies in Behavioral Disabilities, University of Wisconsin. Madison, Wisconsin. 375 Copyright 0 1976 by Academic Press. Inc. All rights of reproduction in any form reserved.
376
TARVER.
ET AL.
recall, have generally not been found to occur before the ages of 12 to 14 years (Druker & Hagen, 1969; Hagen, 1967; Hagen, Meacham, & Mesibov, 1970, Hallahan, Kauffman, & Ball, 1974a; Siegel & Stevenson, 1966). This decrease in attention to incidental information, in turn, may allow for still more efficient processing of central information and thereby account for the further increases in serial recall after the age of 12 years. The hypothesis of a developmental lag in exceptional children leads to the prediction that they progress through the same developmental sequence, but at a slower rate than their normal counterparts. Evidence that noninstitutionalized, educable mental retardates exhibit a developmental lag in both verbal rehearsal strategies (Hagen, Streeter, & Raker, 1974) and selective attention (Hagen & Huntsman, 1971; Hallahan, 1975) has been provided by findings that educable mental retardates perform similarly to MA- but not CA-matched normals. Although there has been much theorizing that another category of exceptional children-the learning disabled-also exhibit a developmental lag (Bender, 1957; Cruickshank et al., 1961; Gallagher, 1966), experimental investigations revealing selective attention deficits (Hallahan, 197.5; Hallahan, Kauffman, & Ball, 1973) and verbal deficits (Blank & Bridger, 1966; McGrady & Olson, 1970) in the learning disabled population have not been conducted from a developmental perspective. Also, no studies have been reported in which the serial recall curves of learning disabled children have been analyzed to investigate deficits in the specific type of verbal rehearsal strategies demonstrated by Ellis (1970) to underlie recall of the primacy items in serial recall tasks. The purposes of the first study reported herein were: (a) to determine if children with learning disabilities are deficient in verbal rehearsal strategies underlying primacy recall, and (b) to investigate further selective attention in the learning disabled. In the second study, older age groups were included to determine whether selective attention and verbal rehearsal deficiencies of the learning disabled represent developmental lags or more basic defects which persist in a qualitatively similar manner across age. In addition, in the second study, an experimentally induced verbal rehearsal condition was included to determine its effects on serial recall and selective attention performance. EXPERIMENT
1
Subjects In both Experiments 1 and 2, learning disabled subjects were white, middle-class boys who had previously been identified as learning disabled by school personnel and/or clinicians and who met the following criteria: IQ of 85 or above on a standardized intelligence test and a discrepancy of at least 6 months between reading achievement and reading expectancy. This
VERBAL
REHEARSAL
377
discrepancy was computed by taking the child’s grade level score on a standardized reading test and subtracting it from his expected reading grade level score [computed as MA minus 5.0 (Dunn, 1963)] at the date of administration of the reading test. Experiment 1 involved the youngest learning disabled boys (N = 18; M CA = 8.68 years, range = 7.58 to 10.00 years; M IQ = 111.56, range = 95 to 139; M MA = 9.71 years, range = 7.50 to 12.97 years) and a normal control group (N = 15; M CA = 8.62 years, range = 7.17 to 10.14 years; M IQ = 117.93, range = 101 to 134; M MA = 10.15 years, range = 8.25 to 13.07 years). The two groups did not differ significantly on CA, IQ, or MA. The reading achievement of the learning disabled group was 2.23 years (range = .07 to 5.1 years) below expected reading grade level. Materials
and Procedure
Hagen’s Central-Incidental learning task, a serial recall task which involves both central and incidental visual stimuli, was administered individually in a single session lasting approximately 20 min. Central test stimuli, identical to those originally devised by Hagen (1967), consisted of seven 6 x 3 in. white cards, each of which contained two 3 x 3 in. black line drawings-an animal picture on the lower half and a familiar object picture (e.g., chair, cup, lamp) on the top half. The same animal and object were always paired together. Children were instructed to pay attention only to the animals. Fourteen seven-item test trials were administered with each item being presented for 2 set and then turned face down to form a horizontal row. Immediately following presentation of the last item in each series, a 3 x 3 in. probe card containing an animal picture only was presented and the child was asked to turn over the test card containing the animal picture identical to the one on the probe card. Only correct first responses were recorded: however, in the case of an incorrect first response, the child was allowed to continue to respond until he chose the correct card. The stimulus cards were presented in random order, with the restrictions that each of the seven animals and each of the seven serial positions was probed twice during the 14 trials. To control for fatigue effects, order of presentation of the 14 seven-item series was counterbalanced, i.e., within each group of subjects, the first child began with Series 1 and continued through Series 14, the second child began with Series 2 and ended with Series 1, and the third child began with Series 3 and ended with Series 2, etc. Proportion of correct first responses on the 14 trials constituted each child’s central recall score. This measure was corrected for possible response bias, i.e., position preference, by use of a procedure whereby correct first choice frequency at each position was expressed as a proportion of total choice frequency at that position (Donaldson & Strang, 1968).
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ET AL.
FIG. 1. Proportion of correct central responses at seven serial positions for normal and learning disabled children in Experiment 1.
Immediately following completion of the central recall phase of the task, the incidental recall task was administered. The child was presented with a 6 x 21 in. white card containing the seven animal pictures on the lower half and seven 3 x 3 in. cards containing individual pictures of the objects. He was asked to match the objects with the animals as they had appeared during the central test trials. Proportion of correct responses constituted the child’s incidental recall score. Results
As depicted in Fig. 1, central recall of the normals was greater than that of the learning disabled. A primacy effect was revealed for the normals but not the learning disabled. A group (learning disabled versus normals) by serial position (I-7) two-way analysis of variance with repeated measures for positions for central recall resulted in significant effects for groups [F(1,31) = 4.88, p < .Ol], positions [F(6,186) = 16.10, p < .Oll, and for the interaction [F(6,186) = 2.80, p < .05]. Crucial to the hypothesis of a verbal rehearsal deficit in the learning disabled was the significant interaction which reflected a primacy effect for the normals, but not for the learning disabled. The following significant paired-comparisons supported this conclusion: For the learning disabled, recall at position 7 was greater than at each of the other positions. All other comparisons were nonsignificant for the learning disabled. For the normals, 1>3, 1>4, 1>5, 2>3,2>4,2<7, 3<6,3<7,4<6,4<7,5<6,5<7,6<7. In addition, recall of the normals was significantly better than that of the learning disabled at positions 1, 2, and 6. Incidental recall of the normals and the learning disabled did not differ significantly (t = 1.40, n.s.; M for the normals -= 3.93, M for the learning
VERBAL
REHEARSAL
379
disabled = 2.89). This lack of difference on incidental recall but significant difference on central recall lends support to the notion of inferior selective attention in learning disabled children. Correlations between central and incidental recall for the two groups were also indicative of poorer selective attention abilities in the learning disabled. The two measures were negatively, though not significantly, correlated for normals (r = -.28) while they were positively correlated for the learning disabled (r = .36,p < .lO). The correlations, thus, support the position that the normal boys excluded incidental for central information but the learning disabled boys did not. However, the two groups did not differ on a composite measure of proportion of correct central responses minus proportion of correct incidental responses (%C-%I) which has been used as an indication of selective attention efficiency (Hallahan, Kauffman, & Ball, 1974a; 1974b; Mercer, Cullinan, Hallahan, & LaFleur, 1975). EXPERIMENT
2
Subjects
Eighteen learning disabled boys at each of two age levels served as subjects. For the older group, M CA was 13.48 years (range = 12.1 to 14.7 years), M IQ was 99.50 (range = 85 to 122); M MA was 13.43 years (range = 10.9 to 16.7 years), and M reading discrepancy was 2.61 years (range = .07 to 4.4 years). For the intermediate age group, M CA was 10.18 years (range = 8.8 to 11.8 years), M IQ was 99.61 (range = 89 to 122), M MA was 10.13 years (range = 8.5 to 12.2 years). IQs of the two age groups did not differ significantly. The 18 children within each age level were grouped into nine pairs matched on CA. One member of each pair was randomly assigned to a standard condition of administration, the other to a verbal rehearsal condition. The two condition groups within each age level did not differ on CA, MA, IQ or reading discrepancy. Task and Procedure
In the standard condition, Hagen’s Central-Incidental task was administered exactly as in Experiment 1. In the verbal rehearsal condition, the child was required verbally to label, chunk, and rehearse items as indicated by the following instructions: It will help you to remember if you say the name of each animal out loud as you see its picture and rehearse the names in groups like this: Say the name of each of the first two animals as you see them. Then repeat the names of both animals in the order in which you saw them (demonstrate). Then, say the names of each of the next three pictures as you see them and repeat all three of those names in order (demonstrate). Then name the last two animal pictures as you see them. After that I will hold up a card just like one of the cards on the table and ask you to find one just like mine and turn it over. Let’s do some for practice first.
380
TARVER.
ET AL
TABLE PROPORTION
1
OF CORRECT RESPONSES ON THREE RESPONSE MEASURES FOR OLDER AND INTERMEDIATE AGE GROUPS UNDER STANDARD AND REHEARSAL CONDITIONS IN EXPERIMENT 2 Older Standard
Intermediate Rehearsal
.60 .43 .I7
Central (%C) Incidental (%I)
%C - %I
Standard
.71 .?5 .46
.43 .32 .I1
Rehearsal
.55 .?9 .26
Results The older group recalled more central information than the intermediate group under both standard and rehearsal conditions. Proportion of correct central responses was analyzed in a three-way analysis of variance (age x conditions x serial positions) with repeated measures for serial positions. The results revealed significant effects for age [F( 1,32) = 13.50,~ < .OOl] and serial positions [F(6,192) = 9.82,~ < .OOl]. The conditions effect and the interactions were not significant. Analysis of simple effects of the serial position factor revealed that recall of position 7 was greater than recall of any of the other positions and recall of position 1 was greater than recall of position 4 and position 5. These position differences, in combination with the absence of significant interactions, reveal a primacy and a recency effect for all four groups of subjects. Incidental recall of the two age groups did not differ significantly and was not affected by the rehearsal condition. A two-way (age x conditions)
FIG. 2. Proportion under
a standard
of correct condition.
central
responses
at seven serial positions
for three age groups
VERBAL
REHEARSAL
381
analysis of variance on proportion of correct incidental responses revealed no significant F ratios. However, selective attention efficiency as measured by %C - %I was facilitated by the rehearsal condition at both age levels. A two-way (age x conditions) analysis of variance on %C - %I revealed a significant conditions effect [F(1,32) = 6.14, p < .051. The absence of a significant interaction indicates that rehearsal had a facilitative effect on selective attention efficiency at both age levels. As depicted in Table 1, the rehearsal condition increased central recall and decreased incidental recall, even though these differences were not significant when analyzed separately. However, a significant facilitative rehearsal effect was revealed when the %C - %I measure which takes into account both the slight increases in central and the slight decreases in incidental was analyzed, DEVELOPMENTAL ANALYSIS OF EXPERIMENTS 1 AND 2 COMBINED
To investigate further the development of verbal rehearsal strategies in the learning disabled, the serial position curves of the younger learning disabled subjects in Experiment 1 (N = 18) were analyzed in combination with those of the intermediate (N = 9) and older (N = 9) age groups under the standard condition in Experiment 2. The serial position curves of the three groups are shown in Fig. 2. A two-way (age x serial positions) analysis of variance revealed significant effects for age [F(2,33) = 7.00, p < .OOl], serial positions [F(6,198) = 60.67,~ < .OOl], and the interaction [F(6,198) = 29.67,~ < .OOl]. Analysis of the simple effects of age revealed that central recall was greater for the older group than for the younger group and greater for the intermediate group than for the younger group. The absence of a significant difference in central recall for the intermediate and older groups appears to conflict with the finding of a significant difference in central recall for these two groups in Experiment 2. However, these seemingly conflicting findings may be explained by the larger N in the analysis in Experiment 2 (due to the inclusion of the rehearsal groups) or by a statistical artifact which has been described by Hale (Note 1). He provided examples of developmental research data which demonstrated that it is possible for two age groups to differ significantly in an analysis involving only those two groups and yet not differ significantly in an analysis in which a third age group has been included. The present data, then, reveal increases in central recall at both the intermediate and the older age levels. Thus, constant developmental increases in central recall were revealed in the learning disabled children. Correlations between central and incidental recall for the three groups were also consistent with the notion that learning disabled children develop, with age, the ability to give up incidental information in order to
382
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ET AL.
process central stimuli more efficiently. As was previously reported, the I’ between central and incidental recall for the youngest learning disabled group was .36 (p < .lO). The YS for the intermediate group (.27) and the oldest group (-. 16), while not significant, suggest a shift with age toward more efficient selective attention processing. Analysis of the simple effects of the serial position factor revealed the following differences; Recall at position 7 was greater than recall at any of the other positions, and recall at position 6 was greater than recall at position 1. That the significant interaction between age and serial position was due to the presence of a primacy effect for the older and intermediate groups and the absence of a primacy effect for the younger group is indicated by the following: (a) Both a primacy and a recency effect were found for both the intermediate and the older age groups in Experiment 2, and (b) a recency effect only was found for the younger age group in Experiment 1. DISCUSSION
The results of Experiment 1 essentially replicate the findings of an earlier study (Hailahan, Kauffman, & Ball, 1973) with a smaller N which found learning disabled boys to evidence a selective attention deficit compared with normal controls. Evidence for this was found in the normals’ superior performance on central but not incidental learning and the negative correlation between central and incidental recall for the normals and a positive correlation for the learning disabled. While the results would have been stronger if the learning disabled had actually recalled significantly more incidental stimuli than the normals, the developmental findings with normals have not always been clear-cut. In other words, older normals may score better than younger normals on central recall but the two groups are often found not to differ on incidental learning. Experiment 1 also revealed the possible source-a verbal rehearsal deficit-of the poorer central recall in learning disabled children. Analysis of serial position curves for the two groups showed a primacy effect for normal but not for learning disabled boys. The hypothesis of a developmental lag in verbal rehearsal strategies in the learning disabled was supported by analysis of the serial position curves of the three age groups. Constant age-related increases in both overall central recall and primacy recall were revealed. That the development of the efficient verbal encoding strategies underlying serial recall takes place at a slower rate in the learning disabled than in normals is indicated by the following findings: (a) the absence of a primacy effect for the learning disabled at eight years of age and the presence of a primacy effect for their normal controls, (b) the presence of a primacy effect for the intermediate learning disabled group (10 years of age), as typically
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383
exhibited by normals of about eight years of age, and (c) the further increase in central recall, due to increased recall at all serial positions, at the oldest age level (12 to 14 years of age), as McCarver (1972) reported for normals of 11 years of age. Thus, the evidence suggests that a developmental lag of about 2 years is characteristic of the learning disabled. That the constant increases in central recall were largely due to developing verbal rehearsal strategies rather than to improvements in selective attention per se is suggested by the absence of a significant decline in incidental learning at any of the age levels investigated. This finding is consistent with the developmental lag hypothesis, as significant declines in incidental recall have generally not been found to occur in normals until sometime between 12 and 14 years of age. In addition, a review of selective attention literature with normals led Hagen and Kail(l975) to conclude that increases in central recall prior to 12 years of age clearly cannot be accounted for by increasing ability to perceptually separate relevant and irrelevant stimuli in order to selectively attend to the relevant, but instead reflect increasingly efficient encoding strategies. It may be that verbal encoding strategies, after becoming highly efficient at the age of 10 to 12 years, acquire attention-focusing properties and thereby contribute to the declines in incidental recall which have been reported to occur between 12 and 14 years of age. Improved selective attention, in turn, may contribute to further increases in serial recall which occur after 12 years of age. To determine whether a developmentally delayed decline in incidental recall occurs in the learning disabled, further research with learning disabled children of 14 to 16 years of age will be required. Such a finding would lend even more support to the developmental lag hypothesis. Confirmation of the existence or nonexistence of a developmental lag in the learning disabled population has important educational implications. A gradual, though slower, rate of progression through the normal developmental sequence is indicative of a quantitative learning deficit, and suggests that those procedures which have been found to increase rate of learning in all populations. e.g., repetition and reinforcement, should be emphasized in the education of the learning disabled. In contrast, confirmation of a more basic, qualitatively different mode of cognitive functioning would imply that teaching methods should be qualitatively different for the learning disabled and normal children. The fact that the experimentally induced verbal rehearsal strategy in Experiment 2 facilitated selective attention efficiency (%C - %I) of the learning disabled at both the intermediate and the older age levels in the present study indicates that performance can be improved by the environmental provision of appropriate strategies. If the deficits of the learning disabled represent a quantitative lag in the learning of appropriate strategies, further improvements in performance might be expected
384
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ET AL.
to result from additional environmental manipulations such as repeated opportunities to use and to be positively reinforced for the use of appropriate strategies. REFERENCES Bender, L. Specific reading disability as a maturational
lag. Bulletin
of the Orfon
Society.
1957, 7, 9- 18.
Blank, M., & Bridger, W. Deficiencies in verbal labeling in retarded readers. American Journal of Orthopsychiatry, 1966, 36, 840-847. Cruickshank, W. M.. Bentzen. F. A., Ratzeburg, F. H., & Tannhauser, M. T. A teaching method for brain-injured and hyperactive children. Syracuse, New York: Syracuse University Press, 1961. Donaldson, M., & Strang, H. Primacy effect in short-term memory in young children. Psychonomic
Science,
1969, 16, 59-60.
Druker, J. F., & Hagen, J. W. Developmental trends in the processing of task-relevant and task-irrelevant information. Child Development, 1969, 40, 371-382. Dunn, L. M. (Ed.) Exceptional children in the schools. New York: Holt, Rinehart & Winston, 1963. Ellis, N. R. Memory processes in retardates and normals. In N. R. Ellis (Ed.), International review of research in mental retardation (Vol. 4). New York: Academic Press, 1970. Gallagher, J. Children with developmental imbalances: A psycho-educational definition. In W. M. Cruickshank (Ed.), The teacherofbrain-injured children. Syracuse, New York: Syracuse University Press, 1966. Hagen, J. W. The effect of distraction on selective attention. Child Development. 1967. 38, 685-694.
Hagen, J. W. Some thoughts on how children learn to remember. Human Development. 197 1, 14, 262- 27 1. Hagen. J. W. & Huntsman, N. J. Selective attention in mental retardates. Derselopmental Psychology, 1971, 5, 151-160. Hagen. J. W., & Kail, R. V. The role of attention in perceptual and cognitive development. In W. M. Cruickshank & D. P. Hallahan (Eds.), Perceptual and learning disabilities in children (Vol. 2). Research and theory. Syracuse, New York: Syracuse University Press. 1975. Hagen, J. W., Meacham, J. A., & Mesibov, G. Verbal labeling, rehearsal, and short-term memory. Cognitive Psychology, 1970, 1, 47-58. Hagen. J. W., Streeter. L. A.. & Raker, R. Labeling, rehearsal and short-term memory in retarded children. Journal of Experimental Child Pgvchology, 1974, 18, 259-268. Hallahan, D. P. Distractibility in the learning disabled child. In W. M. Cruickshank & D. P. Hallahan (Eds.). Perceptual and learning disabilities in children (Vol. 2). Research and theory. Syracuse. New York: Syracuse University Press, 1975. Hallahan, D. P.. Kauffman, J. M., & Ball, D. W. Selective attention and cognitive tempo of low achieving and high achieving sixth grade males. Perceptual and Motor Skills, 1973, 36, 579-583. Hallahan, D. P., Kauffman, J. M., & Ball, D. W. Developmental trends in recall ofcentral and incidental auditory stimuli. Journal of Experimental Child Psychology, 1974, 17, 409-421 .(a) Hallahan, D. P., Kauffman, J. M., & Ball, D. W. Effects of stimulus attenuation on selective attention performance of children. The Joarnal of Genetic Psychology, 1974, 125, 71-77. (b) McCarver, R. B. A developmental study of the effect of organizational cues on short-term memory. Child De\aelopment. 1972. 43, 1317-1325.
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McGrady, H. J., & Olson, D. A. Visual and auditory learning processes in normal children and children with specific learning disabilities. Excepfional Children, 1970, 36, 581-589. Mercer, C. D., Cullinan, D., Hallahan, D. P., & LaFleur, N. K. Modeling and attention-retention in learning disabled children. Journal of Learning Disabilities, 1975, 8, 444-450. Siegel, A. W., & Stevenson, H. W. Incidental learning: A developmental study. Child Development, 1966, 37, 811-818.
REFERENCE NOTE Hale, G. A. A note on use of analysis of variance in developmental research. Testing Service, Princeton, New Jersey, unpublished paper, 1975. RECEIVED:
May 1, 1975;
REVISED:
January 26, 1976.
Educational
OF EXPERIMENTAL
CHILD
PSYCHOLOGY
22, 375-385 (1976)
Verbal Rehearsal and Selective Attention in Children with Learning Disabilities: A Developmental Lag SARA G. TARVER',DANIEL P. HALLAHAN*,JAMES AND DONALD W. BALL* Universiiy
of Wisconsin,’
and
University
M. KAUFFMAN*,
of Virginia’
To investigate the development of verbal rehearsal strategies and selective attention in learning disabled children, Hagen’s Central-Incidental task was administered to younger learnink disabled (M CA = 8.68 years) and normal (M CA = 8.62 years) boys in Experiment I and to intermediate (M CA = 10.18 years) and older (M CA = 13.48 years) learning disabled boys in Experiment 2. Also, in Experiment 2, an experimentally induced verbal rehearsal condition was included to determine its effects on serial recall and selective attention performance. In Experiment 1, the serial position curve of the normals revealed both a primacy and a recency effect, whereas that of the learning disabled revealed a recency effect only. In Experiment 2, both the intermediate and the older learning disabled exhibited both primacy and recency effects under both standard and rehearsal conditions. A developmental analysis of central recall for the three learning disabled groups revealed constant age-related increases in overall central recall and in primacy recall. That the normals recalled more central, but not more incidental, information than the learning disabled in Experiment 1 suggests that the learning disabled are deficient in selective attention. Correlational findings suggest that the selective attention of the learning disabled improves with age. The results were interpreted as support for the hypothesis of a developmental lag in the learning disabled population.
Age-related increases in serial recall in normal children have been found to reflect a series of changes in verbal encoding strategies and selective attention. Verbal encoding strategies become increasingly efficient with age, progressing from simple verbal labeling strategies employed prior to the age of 8 years to more efficient cumulative verbal rehearsal strategies by the age of 10 years (Hagen, 1971) and then to strategies including labeling, cumulative rehearsal, and chunking by the age of about 11 years (McCarver, 1972). Improvements in selective attention performance, as evidenced by a decline in incidental relative to central recall and /or a shift from a positive to a negative correlation between incidental and central Experiment 2 of this report is based on the doctoral dissertation of the senior author submitted in partial fulfillment of the requirements for the Ph.D. degree at the University of Virginia. The authors are indebted to Jean N. Dickinson (University of Richmond), Richard A. Bell (The Stony Point School), Mary Louise Trusdell (The New Community School), and John B. Finkler (Chesterfield County Public Schools). Reprints are available from Dr. Sara Tarver, Department of Studies in Behavioral Disabilities, University of Wisconsin. Madison, Wisconsin. 375 Copyright 0 1976 by Academic Press. Inc. All rights of reproduction in any form reserved.
376
TARVER.
ET AL.
recall, have generally not been found to occur before the ages of 12 to 14 years (Druker & Hagen, 1969; Hagen, 1967; Hagen, Meacham, & Mesibov, 1970, Hallahan, Kauffman, & Ball, 1974a; Siegel & Stevenson, 1966). This decrease in attention to incidental information, in turn, may allow for still more efficient processing of central information and thereby account for the further increases in serial recall after the age of 12 years. The hypothesis of a developmental lag in exceptional children leads to the prediction that they progress through the same developmental sequence, but at a slower rate than their normal counterparts. Evidence that noninstitutionalized, educable mental retardates exhibit a developmental lag in both verbal rehearsal strategies (Hagen, Streeter, & Raker, 1974) and selective attention (Hagen & Huntsman, 1971; Hallahan, 1975) has been provided by findings that educable mental retardates perform similarly to MA- but not CA-matched normals. Although there has been much theorizing that another category of exceptional children-the learning disabled-also exhibit a developmental lag (Bender, 1957; Cruickshank et al., 1961; Gallagher, 1966), experimental investigations revealing selective attention deficits (Hallahan, 197.5; Hallahan, Kauffman, & Ball, 1973) and verbal deficits (Blank & Bridger, 1966; McGrady & Olson, 1970) in the learning disabled population have not been conducted from a developmental perspective. Also, no studies have been reported in which the serial recall curves of learning disabled children have been analyzed to investigate deficits in the specific type of verbal rehearsal strategies demonstrated by Ellis (1970) to underlie recall of the primacy items in serial recall tasks. The purposes of the first study reported herein were: (a) to determine if children with learning disabilities are deficient in verbal rehearsal strategies underlying primacy recall, and (b) to investigate further selective attention in the learning disabled. In the second study, older age groups were included to determine whether selective attention and verbal rehearsal deficiencies of the learning disabled represent developmental lags or more basic defects which persist in a qualitatively similar manner across age. In addition, in the second study, an experimentally induced verbal rehearsal condition was included to determine its effects on serial recall and selective attention performance. EXPERIMENT
1
Subjects In both Experiments 1 and 2, learning disabled subjects were white, middle-class boys who had previously been identified as learning disabled by school personnel and/or clinicians and who met the following criteria: IQ of 85 or above on a standardized intelligence test and a discrepancy of at least 6 months between reading achievement and reading expectancy. This
VERBAL
REHEARSAL
377
discrepancy was computed by taking the child’s grade level score on a standardized reading test and subtracting it from his expected reading grade level score [computed as MA minus 5.0 (Dunn, 1963)] at the date of administration of the reading test. Experiment 1 involved the youngest learning disabled boys (N = 18; M CA = 8.68 years, range = 7.58 to 10.00 years; M IQ = 111.56, range = 95 to 139; M MA = 9.71 years, range = 7.50 to 12.97 years) and a normal control group (N = 15; M CA = 8.62 years, range = 7.17 to 10.14 years; M IQ = 117.93, range = 101 to 134; M MA = 10.15 years, range = 8.25 to 13.07 years). The two groups did not differ significantly on CA, IQ, or MA. The reading achievement of the learning disabled group was 2.23 years (range = .07 to 5.1 years) below expected reading grade level. Materials
and Procedure
Hagen’s Central-Incidental learning task, a serial recall task which involves both central and incidental visual stimuli, was administered individually in a single session lasting approximately 20 min. Central test stimuli, identical to those originally devised by Hagen (1967), consisted of seven 6 x 3 in. white cards, each of which contained two 3 x 3 in. black line drawings-an animal picture on the lower half and a familiar object picture (e.g., chair, cup, lamp) on the top half. The same animal and object were always paired together. Children were instructed to pay attention only to the animals. Fourteen seven-item test trials were administered with each item being presented for 2 set and then turned face down to form a horizontal row. Immediately following presentation of the last item in each series, a 3 x 3 in. probe card containing an animal picture only was presented and the child was asked to turn over the test card containing the animal picture identical to the one on the probe card. Only correct first responses were recorded: however, in the case of an incorrect first response, the child was allowed to continue to respond until he chose the correct card. The stimulus cards were presented in random order, with the restrictions that each of the seven animals and each of the seven serial positions was probed twice during the 14 trials. To control for fatigue effects, order of presentation of the 14 seven-item series was counterbalanced, i.e., within each group of subjects, the first child began with Series 1 and continued through Series 14, the second child began with Series 2 and ended with Series 1, and the third child began with Series 3 and ended with Series 2, etc. Proportion of correct first responses on the 14 trials constituted each child’s central recall score. This measure was corrected for possible response bias, i.e., position preference, by use of a procedure whereby correct first choice frequency at each position was expressed as a proportion of total choice frequency at that position (Donaldson & Strang, 1968).
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FIG. 1. Proportion of correct central responses at seven serial positions for normal and learning disabled children in Experiment 1.
Immediately following completion of the central recall phase of the task, the incidental recall task was administered. The child was presented with a 6 x 21 in. white card containing the seven animal pictures on the lower half and seven 3 x 3 in. cards containing individual pictures of the objects. He was asked to match the objects with the animals as they had appeared during the central test trials. Proportion of correct responses constituted the child’s incidental recall score. Results
As depicted in Fig. 1, central recall of the normals was greater than that of the learning disabled. A primacy effect was revealed for the normals but not the learning disabled. A group (learning disabled versus normals) by serial position (I-7) two-way analysis of variance with repeated measures for positions for central recall resulted in significant effects for groups [F(1,31) = 4.88, p < .Ol], positions [F(6,186) = 16.10, p < .Oll, and for the interaction [F(6,186) = 2.80, p < .05]. Crucial to the hypothesis of a verbal rehearsal deficit in the learning disabled was the significant interaction which reflected a primacy effect for the normals, but not for the learning disabled. The following significant paired-comparisons supported this conclusion: For the learning disabled, recall at position 7 was greater than at each of the other positions. All other comparisons were nonsignificant for the learning disabled. For the normals, 1>3, 1>4, 1>5, 2>3,2>4,2<7, 3<6,3<7,4<6,4<7,5<6,5<7,6<7. In addition, recall of the normals was significantly better than that of the learning disabled at positions 1, 2, and 6. Incidental recall of the normals and the learning disabled did not differ significantly (t = 1.40, n.s.; M for the normals -= 3.93, M for the learning
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379
disabled = 2.89). This lack of difference on incidental recall but significant difference on central recall lends support to the notion of inferior selective attention in learning disabled children. Correlations between central and incidental recall for the two groups were also indicative of poorer selective attention abilities in the learning disabled. The two measures were negatively, though not significantly, correlated for normals (r = -.28) while they were positively correlated for the learning disabled (r = .36,p < .lO). The correlations, thus, support the position that the normal boys excluded incidental for central information but the learning disabled boys did not. However, the two groups did not differ on a composite measure of proportion of correct central responses minus proportion of correct incidental responses (%C-%I) which has been used as an indication of selective attention efficiency (Hallahan, Kauffman, & Ball, 1974a; 1974b; Mercer, Cullinan, Hallahan, & LaFleur, 1975). EXPERIMENT
2
Subjects
Eighteen learning disabled boys at each of two age levels served as subjects. For the older group, M CA was 13.48 years (range = 12.1 to 14.7 years), M IQ was 99.50 (range = 85 to 122); M MA was 13.43 years (range = 10.9 to 16.7 years), and M reading discrepancy was 2.61 years (range = .07 to 4.4 years). For the intermediate age group, M CA was 10.18 years (range = 8.8 to 11.8 years), M IQ was 99.61 (range = 89 to 122), M MA was 10.13 years (range = 8.5 to 12.2 years). IQs of the two age groups did not differ significantly. The 18 children within each age level were grouped into nine pairs matched on CA. One member of each pair was randomly assigned to a standard condition of administration, the other to a verbal rehearsal condition. The two condition groups within each age level did not differ on CA, MA, IQ or reading discrepancy. Task and Procedure
In the standard condition, Hagen’s Central-Incidental task was administered exactly as in Experiment 1. In the verbal rehearsal condition, the child was required verbally to label, chunk, and rehearse items as indicated by the following instructions: It will help you to remember if you say the name of each animal out loud as you see its picture and rehearse the names in groups like this: Say the name of each of the first two animals as you see them. Then repeat the names of both animals in the order in which you saw them (demonstrate). Then, say the names of each of the next three pictures as you see them and repeat all three of those names in order (demonstrate). Then name the last two animal pictures as you see them. After that I will hold up a card just like one of the cards on the table and ask you to find one just like mine and turn it over. Let’s do some for practice first.
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TABLE PROPORTION
1
OF CORRECT RESPONSES ON THREE RESPONSE MEASURES FOR OLDER AND INTERMEDIATE AGE GROUPS UNDER STANDARD AND REHEARSAL CONDITIONS IN EXPERIMENT 2 Older Standard
Intermediate Rehearsal
.60 .43 .I7
Central (%C) Incidental (%I)
%C - %I
Standard
.71 .?5 .46
.43 .32 .I1
Rehearsal
.55 .?9 .26
Results The older group recalled more central information than the intermediate group under both standard and rehearsal conditions. Proportion of correct central responses was analyzed in a three-way analysis of variance (age x conditions x serial positions) with repeated measures for serial positions. The results revealed significant effects for age [F( 1,32) = 13.50,~ < .OOl] and serial positions [F(6,192) = 9.82,~ < .OOl]. The conditions effect and the interactions were not significant. Analysis of simple effects of the serial position factor revealed that recall of position 7 was greater than recall of any of the other positions and recall of position 1 was greater than recall of position 4 and position 5. These position differences, in combination with the absence of significant interactions, reveal a primacy and a recency effect for all four groups of subjects. Incidental recall of the two age groups did not differ significantly and was not affected by the rehearsal condition. A two-way (age x conditions)
FIG. 2. Proportion under
a standard
of correct condition.
central
responses
at seven serial positions
for three age groups
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analysis of variance on proportion of correct incidental responses revealed no significant F ratios. However, selective attention efficiency as measured by %C - %I was facilitated by the rehearsal condition at both age levels. A two-way (age x conditions) analysis of variance on %C - %I revealed a significant conditions effect [F(1,32) = 6.14, p < .051. The absence of a significant interaction indicates that rehearsal had a facilitative effect on selective attention efficiency at both age levels. As depicted in Table 1, the rehearsal condition increased central recall and decreased incidental recall, even though these differences were not significant when analyzed separately. However, a significant facilitative rehearsal effect was revealed when the %C - %I measure which takes into account both the slight increases in central and the slight decreases in incidental was analyzed, DEVELOPMENTAL ANALYSIS OF EXPERIMENTS 1 AND 2 COMBINED
To investigate further the development of verbal rehearsal strategies in the learning disabled, the serial position curves of the younger learning disabled subjects in Experiment 1 (N = 18) were analyzed in combination with those of the intermediate (N = 9) and older (N = 9) age groups under the standard condition in Experiment 2. The serial position curves of the three groups are shown in Fig. 2. A two-way (age x serial positions) analysis of variance revealed significant effects for age [F(2,33) = 7.00, p < .OOl], serial positions [F(6,198) = 60.67,~ < .OOl], and the interaction [F(6,198) = 29.67,~ < .OOl]. Analysis of the simple effects of age revealed that central recall was greater for the older group than for the younger group and greater for the intermediate group than for the younger group. The absence of a significant difference in central recall for the intermediate and older groups appears to conflict with the finding of a significant difference in central recall for these two groups in Experiment 2. However, these seemingly conflicting findings may be explained by the larger N in the analysis in Experiment 2 (due to the inclusion of the rehearsal groups) or by a statistical artifact which has been described by Hale (Note 1). He provided examples of developmental research data which demonstrated that it is possible for two age groups to differ significantly in an analysis involving only those two groups and yet not differ significantly in an analysis in which a third age group has been included. The present data, then, reveal increases in central recall at both the intermediate and the older age levels. Thus, constant developmental increases in central recall were revealed in the learning disabled children. Correlations between central and incidental recall for the three groups were also consistent with the notion that learning disabled children develop, with age, the ability to give up incidental information in order to
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process central stimuli more efficiently. As was previously reported, the I’ between central and incidental recall for the youngest learning disabled group was .36 (p < .lO). The YS for the intermediate group (.27) and the oldest group (-. 16), while not significant, suggest a shift with age toward more efficient selective attention processing. Analysis of the simple effects of the serial position factor revealed the following differences; Recall at position 7 was greater than recall at any of the other positions, and recall at position 6 was greater than recall at position 1. That the significant interaction between age and serial position was due to the presence of a primacy effect for the older and intermediate groups and the absence of a primacy effect for the younger group is indicated by the following: (a) Both a primacy and a recency effect were found for both the intermediate and the older age groups in Experiment 2, and (b) a recency effect only was found for the younger age group in Experiment 1. DISCUSSION
The results of Experiment 1 essentially replicate the findings of an earlier study (Hailahan, Kauffman, & Ball, 1973) with a smaller N which found learning disabled boys to evidence a selective attention deficit compared with normal controls. Evidence for this was found in the normals’ superior performance on central but not incidental learning and the negative correlation between central and incidental recall for the normals and a positive correlation for the learning disabled. While the results would have been stronger if the learning disabled had actually recalled significantly more incidental stimuli than the normals, the developmental findings with normals have not always been clear-cut. In other words, older normals may score better than younger normals on central recall but the two groups are often found not to differ on incidental learning. Experiment 1 also revealed the possible source-a verbal rehearsal deficit-of the poorer central recall in learning disabled children. Analysis of serial position curves for the two groups showed a primacy effect for normal but not for learning disabled boys. The hypothesis of a developmental lag in verbal rehearsal strategies in the learning disabled was supported by analysis of the serial position curves of the three age groups. Constant age-related increases in both overall central recall and primacy recall were revealed. That the development of the efficient verbal encoding strategies underlying serial recall takes place at a slower rate in the learning disabled than in normals is indicated by the following findings: (a) the absence of a primacy effect for the learning disabled at eight years of age and the presence of a primacy effect for their normal controls, (b) the presence of a primacy effect for the intermediate learning disabled group (10 years of age), as typically
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exhibited by normals of about eight years of age, and (c) the further increase in central recall, due to increased recall at all serial positions, at the oldest age level (12 to 14 years of age), as McCarver (1972) reported for normals of 11 years of age. Thus, the evidence suggests that a developmental lag of about 2 years is characteristic of the learning disabled. That the constant increases in central recall were largely due to developing verbal rehearsal strategies rather than to improvements in selective attention per se is suggested by the absence of a significant decline in incidental learning at any of the age levels investigated. This finding is consistent with the developmental lag hypothesis, as significant declines in incidental recall have generally not been found to occur in normals until sometime between 12 and 14 years of age. In addition, a review of selective attention literature with normals led Hagen and Kail(l975) to conclude that increases in central recall prior to 12 years of age clearly cannot be accounted for by increasing ability to perceptually separate relevant and irrelevant stimuli in order to selectively attend to the relevant, but instead reflect increasingly efficient encoding strategies. It may be that verbal encoding strategies, after becoming highly efficient at the age of 10 to 12 years, acquire attention-focusing properties and thereby contribute to the declines in incidental recall which have been reported to occur between 12 and 14 years of age. Improved selective attention, in turn, may contribute to further increases in serial recall which occur after 12 years of age. To determine whether a developmentally delayed decline in incidental recall occurs in the learning disabled, further research with learning disabled children of 14 to 16 years of age will be required. Such a finding would lend even more support to the developmental lag hypothesis. Confirmation of the existence or nonexistence of a developmental lag in the learning disabled population has important educational implications. A gradual, though slower, rate of progression through the normal developmental sequence is indicative of a quantitative learning deficit, and suggests that those procedures which have been found to increase rate of learning in all populations. e.g., repetition and reinforcement, should be emphasized in the education of the learning disabled. In contrast, confirmation of a more basic, qualitatively different mode of cognitive functioning would imply that teaching methods should be qualitatively different for the learning disabled and normal children. The fact that the experimentally induced verbal rehearsal strategy in Experiment 2 facilitated selective attention efficiency (%C - %I) of the learning disabled at both the intermediate and the older age levels in the present study indicates that performance can be improved by the environmental provision of appropriate strategies. If the deficits of the learning disabled represent a quantitative lag in the learning of appropriate strategies, further improvements in performance might be expected
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to result from additional environmental manipulations such as repeated opportunities to use and to be positively reinforced for the use of appropriate strategies. REFERENCES Bender, L. Specific reading disability as a maturational
lag. Bulletin
of the Orfon
Society.
1957, 7, 9- 18.
Blank, M., & Bridger, W. Deficiencies in verbal labeling in retarded readers. American Journal of Orthopsychiatry, 1966, 36, 840-847. Cruickshank, W. M.. Bentzen. F. A., Ratzeburg, F. H., & Tannhauser, M. T. A teaching method for brain-injured and hyperactive children. Syracuse, New York: Syracuse University Press, 1961. Donaldson, M., & Strang, H. Primacy effect in short-term memory in young children. Psychonomic
Science,
1969, 16, 59-60.
Druker, J. F., & Hagen, J. W. Developmental trends in the processing of task-relevant and task-irrelevant information. Child Development, 1969, 40, 371-382. Dunn, L. M. (Ed.) Exceptional children in the schools. New York: Holt, Rinehart & Winston, 1963. Ellis, N. R. Memory processes in retardates and normals. In N. R. Ellis (Ed.), International review of research in mental retardation (Vol. 4). New York: Academic Press, 1970. Gallagher, J. Children with developmental imbalances: A psycho-educational definition. In W. M. Cruickshank (Ed.), The teacherofbrain-injured children. Syracuse, New York: Syracuse University Press, 1966. Hagen, J. W. The effect of distraction on selective attention. Child Development. 1967. 38, 685-694.
Hagen, J. W. Some thoughts on how children learn to remember. Human Development. 197 1, 14, 262- 27 1. Hagen. J. W. & Huntsman, N. J. Selective attention in mental retardates. Derselopmental Psychology, 1971, 5, 151-160. Hagen. J. W., & Kail, R. V. The role of attention in perceptual and cognitive development. In W. M. Cruickshank & D. P. Hallahan (Eds.), Perceptual and learning disabilities in children (Vol. 2). Research and theory. Syracuse, New York: Syracuse University Press. 1975. Hagen, J. W., Meacham, J. A., & Mesibov, G. Verbal labeling, rehearsal, and short-term memory. Cognitive Psychology, 1970, 1, 47-58. Hagen. J. W., Streeter. L. A.. & Raker, R. Labeling, rehearsal and short-term memory in retarded children. Journal of Experimental Child Pgvchology, 1974, 18, 259-268. Hallahan, D. P. Distractibility in the learning disabled child. In W. M. Cruickshank & D. P. Hallahan (Eds.). Perceptual and learning disabilities in children (Vol. 2). Research and theory. Syracuse. New York: Syracuse University Press, 1975. Hallahan, D. P.. Kauffman, J. M., & Ball, D. W. Selective attention and cognitive tempo of low achieving and high achieving sixth grade males. Perceptual and Motor Skills, 1973, 36, 579-583. Hallahan, D. P., Kauffman, J. M., & Ball, D. W. Developmental trends in recall ofcentral and incidental auditory stimuli. Journal of Experimental Child Psychology, 1974, 17, 409-421 .(a) Hallahan, D. P., Kauffman, J. M., & Ball, D. W. Effects of stimulus attenuation on selective attention performance of children. The Joarnal of Genetic Psychology, 1974, 125, 71-77. (b) McCarver, R. B. A developmental study of the effect of organizational cues on short-term memory. Child De\aelopment. 1972. 43, 1317-1325.
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McGrady, H. J., & Olson, D. A. Visual and auditory learning processes in normal children and children with specific learning disabilities. Excepfional Children, 1970, 36, 581-589. Mercer, C. D., Cullinan, D., Hallahan, D. P., & LaFleur, N. K. Modeling and attention-retention in learning disabled children. Journal of Learning Disabilities, 1975, 8, 444-450. Siegel, A. W., & Stevenson, H. W. Incidental learning: A developmental study. Child Development, 1966, 37, 811-818.
REFERENCE NOTE Hale, G. A. A note on use of analysis of variance in developmental research. Testing Service, Princeton, New Jersey, unpublished paper, 1975. RECEIVED:
May 1, 1975;
REVISED:
January 26, 1976.
Educational