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Neurodevelopmental and racial differences in tactile-visual (cross-modal) discrimination in normal black and white children
Neurodevelopmental Differences Discrimination
and Racial
in Tactile-Visual in Normal
(Cross-Modal) Black and White
Children Lola 1. Heverly Orlando,
Florida
Walter Isaac
of Georgia
University
George W. Hynd University
of Georgia and Medical College of Georgia
Controversy exists as to when those functions associated with the left tertiary cortex become fully developed in children. To address this issue, neuropsychological development of tactile-visual (cross-modal) discrimination was assessed in 200 normal children aged 5 through 9 years. The factors of gender and race (black, white) were evaluated across this age span. A three-factor ANOVA revealed no gender differences, but signtficant main effects for age and race existed. There were no significant interactions. White children outperformed black children across all ages, and Sheffe’s post-hoc comparisons revealed that, by age 7, children have mastered those basic cross-modal functions necessary for complex higher cognitive processes. The implications of these findings are discussed.
Functional and structural asymmetries in the brain are well documented, and it is assumed that, in terms of the hierarchical organization of the nervous system, the greatest degree of asymmetry is found in those regions
Requests for reprints may be directed to George ogy, 325 Aderhold Hall, University of Georgia,
W. Hynd, Department of Educational Athens, GA, 30602, USA.
139
Psychol-
140
L. L. Heverly,
UT Issac, and G. W Hynd
of the cortex associated with higher cognitive functions (Galaburda & Eidelberg, 1982; Geschwind & Levitsky, 1968; Witelson & Pallie, 1973). In particular, it seems as though the region of the left parietal-occipital cortex is significantly asymmetrical in humans (Hier, LeMay, Rosenberger, & Perlo, 1978) and that this asymmetry is significantly related to cross-modal integrative functioning (e.g., Luria, 1980; Whitaker, 1976). Luria (1980) has suggested that, by age 7, the tertitary cortex has reached sufficient maturity in children to be fully functional in the integration of sensory input from the auditory, somatosensory, and visual cortexes. Evidence does exist suggesting that tactile discrimination develops at an early age (e.g., Soroka, Corter, & Abramovitch, 1979) and that by age 4 most children can integrate and associate visual stimuli with tactile perception (Altman & Bridge, 1968). However, relatively few studies have directly assessed whether tactile-visual cross-modal integration is developed by age 7, as suggested by Luria (1980). Fishbin, Decker, and Wilcox (1977) examined the cross-modal transfer of spatial information, using 48 first-, second-, and fourth-grade males and females. The spatial task required the perception of a group of three geometrical objects. The stimuli were presented either tactilly or visually, and the choice stimuli were photographs of different configurations. Of interest, no difference was found between the intramodal and the cross-modal conditions. Generally, the older children did better on these tasks. In another study of developmental changes in hemispheric specialization for tactile-spatial ability, Flannery and Balling (1979) also found age-related differences. Their subjects included 64 first-, third-, and fifth-grade students, plus a group of adults. Each subject completed 40 trials of exploring nonsense forms using only finger motion. Two conditions were used: In the first condition, the stimulus forms were presented successively to the same hand, and, in the second condition, the stimuli were presented simultaneously to both hands. The subjects were required to determine if the forms were the same or different. The results indicated no significant differences in right-hand-left-hand performance in the first- or third-grade subjects; however, the left hand (right hemisphere) was more accurate in discrimination for the fifth graders and the adults. This indicated an age factor. A sex difference was found only in the adult group, with the male subjects making fewer errors than the female subjects. Finally, it was found that the simultaneous presentation of the two stimuli forms was more difficult than the first condition. In the context of the present investigation one other study deserves mention. Hatta, Yamamoto, Kawabata, and Tsutui (1981) studied hemispheric specialization for tactile recognition in normal children. The subjects were eight boys and eight girls at the second-, fourth-, and sixth-grade levels.
These subjects were required to tactilly explore objects and match each with an analogue object on visual display. The performance of right and left hands was compared. No significant differences were found in second and fourth graders; however, the sixth graders were more accurate at this task with their left hand. Sex differences were noted. Right-hand performance was superior to left in females, but no right-handed-left-handed difference was exhibited in the males’ performance on this task. Consequently, it would appear that older children consistently do better on cross-modal tasks involving tactile-visual integration, but, according to various studies, there is variability as to when this skill reaches full maturity. Also, although sex differences appear to exist, they are found inconsistently. In the Hatta et al. (1981) study, females showed a hand preference, whereas, in the Flannery and Balling (1979) study, males did better than females. To date, no study has evaluated right-hand tactile-visual integration in a developmental population incorporating race and gender as major factors. Presumably, right-hand performance reflects the functioning of the left tertiary cortex in cross-modal integration and thus allows for a more objective evaluation of Luria’s (1980) hypothesis.
Subjects
This study included a sample of 200 average-functioning, right-handed children from a South Carolina school district of approximately 50,000 students. The sample was composed of 40 children at each age level from the ages of S through 9, Each group of 40 children at the five age levels examined comprised 20 males and 20 females. Each of these gender groups included 10 white and 10 black children. All subjects were previously familiarized with the examiner, and the subject population included only those normal children who had not been referred for special services. All children had normal vision and hearing. Measure
The instrument designed to assess stereognosis as used in this study consisted of a box into which the child could reach through a sleeve to feel various geometric shapes without visual input. Two sets of identical threedimensional wooden shapes were devised. Each set consisted of nine shapes. These shapes were cut from an 8.35 cm block and painted white. The shapes included a circle, a square, a triangle, an octagon, a cross, a six-pointed star, a five-pointed star, a small diamond, and a large diamond.
L. L. Heverly, W Issac, and G. W Hynd
142
Procedure Each child was asked to reach into the box with her or his right hand and to explore tactilly the geometric shape placed in her or his palm. The child was then required to select the same shape from an alternative set of blocks placed before her or him by pointing with the left hand. There was no time limit, and, if the child responded verbally, she or he was requested to point to her or his selection. The order of presentation of the nine geometric shapes was determined by a table of random numbers. The set of nine shapes was presented for three consecutive trials, with each trial randomly ordered. Thus, a total of 27 presentations was possible. Each of the responses. was scored as either correct or incorrect. The total possible score was a maximum of 27 correct choices. Data Analysis A 5 (age) x 2 (sex) x 2 (race) analysis of variance (ANOVA) was used to evaluate the data. Because all were independent measures, a single withingroups error term was used. Sheffe’s (Keppel, 1982) post-hoc comparisons of the age means was then computed. RESULTS Table 1 presents the means and standard deviations for all factors. Although no significant effect was found for gender, F( 1, 180) = 2.47, p > .05, there was, as expected, a significant effect for age, F(4, 180) = 22.43, p < .Ol. TABLE 1 Means and Standard Deviations by Age Groups for Black and White Children Age 5-o
to 5-11
6-O to 6-11 7-o to 7-11 8-O to 8-l 1 9-o to 9-11
Race
N
Mean
Standard Deviation
White Black White Black White Black White Black White Black
20 20 20 20 20 20 20 20 20 20
18.00 16.35 21.20 19.35 22.40 22.10 23.25 22.35 23.50 22.65
4.64 3.91
3.20 4.41 3.20 2.23 2.68 3.04 1.96 2.72
Note. The 20 subjects for each racial group consisted of 10 males and 10 females.
Neurodevelopmental
Changes
I43
Also, a significant effect was found for race, F( 1,180) = 5.70, p < .05. The white subjects were found to perform significantly better on this task than the black subjects. None of the two- or three-way interactions was statistically significant (p > .05). These results support previous research, which has indicated an increase in accuracy of performance on tactile-visual cross-modality functioning in normally developing children as they get older (Flannery & Balling, 1979). Sheffe’s comparison of means was used to determine if there were significant differences among the age levels. This procedure indicated that the j-yearold subjects performed significantly differently from the older age groups, F(4,180) = 17.81, pc .Ol. This showed that all of the older children performed significantly better on this task than the 5-year-olds. The 6-year-old subjects did not perform significantly differently from the 7-year-olds, F(4,180) = 7.23, p > .Ol. However, they did perform significantly differently from the 8-year-old group, F(4,180) = 8.12, p< .05, and from the 9-year-old group, F(4,180) = 14.53, p< .Ol. This indicated that the S- and g-year-old subjects performed significantly better than the 6-year-old subjects. No other significant differences (pc .05) were found among the age groups, indicating that the 7-, 8-, and 9-year-old subjects performed similarly. In summary, on this tactile-visual cross-modality task, no difference in male-female performance was found. As predicted, significant differences were found among the age groups, with older children performing significantly better than younger children. Unique to this investigation, and a finding not reported elsewhere, is the fact that black children consistently did more poorly in cross-modal tactile-visual recognition than the white children across all ages from 5 through 9. DISCUSSION
The results of this study support the notion that patterns of parietal-lobe function improve with age in children. In the groups studied, ages 5 through 9, increasing accuracy on the tactile-visual task was evident with age, and significant differences were found between the age groups. Five-year-olds performed significantly less accurately than all the other groups of children. No significant difference was found between 6- and 7-year-olds; however, 6year-olds performed significantly less accurately than 8- and 9-year-olds. No significant differences were found among the 7-, 8-, and 9-year-old age groups. Luria (1973) stated that the tertiary zones of the parietal lobe do not become fully operative until 7 years of age. The findings of this study lend objective developmental evidence to Luria’s hypothesis. It is important that the finding that racial differences exist on this task involving cross-modal integration lends increasing support to a growing body of literature that
144
L. L. Heverly,
W Issac, and G. W Hynd
indicates the importance of culture on the development of neuropsychological abilities (e.g., Albert & Obler, 1978; Hynd, Teeter, & Stewart, 1980). In addition to adding support to the findings of Flannery and Balling (1979), these results relate to those reported by Satz and his coheagues (Satz, Taylor, Friel, & Fletcher, 1978). Based on the premise that children who are delayed in perceptual-motor development and cross-modal sensory integration will also be delayed in learning to read, Satz assessed the predictive validity of a number of measures in a large-scale longitudinal study. Having assessed them in kindergarten and followed them through the fifth grade, Satz found that three of the five overall best predictors of reading failure were associated with tactile-visual functioning (finger localization, the Beery Visual-Motor Integration Test, and a visual-recognition task). Thus, in terms of neurodevelopmental processes important in the acquisition of prerequisite reading skills, those associated with cross-modal sensory integration are vitally important. It is in this regard that the present study is relevant. Those basic crossmodal integrative skills associated with the left tertiary cortex seem fully developed by age 7, when most normal children are developing an essential comprehension of the reading process using primarily visuo-spatial or orthographic attributes of memory (Hynd & Obrzut, 1977). The racial differences found in this study warrant further evaluation. They also call into question the applicability of norms developed for neuropsychological tests, in which potential racial differences are not considered across developmental levels. Clearly, the effect of culture or ethnic group in the development of neuropsychological abilities is not yet well defined. If the tasks used in this study are reflective of neurodevelopmental process associated with left tertiary cortex functioning, then do they suggest delay of important basic integrative process? Also, is there some point at which black children reach the level of functioning of white children, and what predictive effect might thus exist across age groups according to ethnic group? Further study seems indicated to address these and related issues regarding the development of neuropsychological process in normal children.
REFERENCES Albert,
M. L., & Obler, L. K. (1978). The 6ifi~g~u~ brain. New York: Academic
fliank, M., Attman, & Bridger (1968). Cross-modal transfer school children. fsychonomic Science, 10, 5 l-52. Fishbein, H., Decker, J., & Wilcox, P. (1977). Cross-modality
of form transfer
Press.
discrimination of spatial
in pre-
information.
British Journal of Psychology, 68, 503-508. Flannery, R. C., & Balling, J. D. (1979). Developmental changes in hemispheric specialization for tactile spatial ability. Developmenta/ Psycho/ogy, 15. 364-372. Galaburda, A. M., & Eidelberg, D. (1982). Symmetry and asymmetry in the human posterior
Neurodevelopmental
Changes
145
thalamus: II. Thalamic lesions in a case of developmental dyslexia. Archives of Neurology, 39, 333-336. Geschwind, N., & Levitsky, W. (1968). Left-right asymmetries in temporal speech region. Science, 161, 186-187. Hatta, T., Yamamoto, M., Kawabata, Y., & Tsutui, K. (1981). Development of hemisphere specialization for tactile recognition in normal children. Cortex, 17, 611-616. dyslexia: Hier, D. B., LeMay, M., Rosenberger, x., & Perlo, V. P. (1978). Developmental Subgroup with a reversal of cerebral asymmetry. Archives of Neurology, 35, 90-92. Hynd, Cl. W., & Obrzut, J. E. (1977). Developmental shift hypothesis and preferred memory attributes in elementary school children. Perceptuul and Motor Skills, 46, 167-170. Hynd, G. W., Teeter, A., & Stewart, J. (1980). Acculturation and the lateralization of speech in bilingual Native Americans. International Journal of Neuroscience, 11, 1-7. Keppel, G. (1982). Design and analysis: A researcher’s handbook (2nd ed.). New Jersey: Prentice-Hall. Luria, A. R. (1973). The working brain: An introduction to neuropsychology. New York: Basic Books. Luria, A. R. (1980). Higher corticulfunctions in man. New York: Basic Books. Satz, P., Taylor, H. G., Friel, J., & Fletcher, J. M. (1978). Some developmental and predictive precursors of reading disabilities: A six year follow-up. In A. L. Benton & D. Pearl (Eds.), Dyslexia: An appraisal of current knowledge. New York: Oxford University Press. Soroka, S. M., Corter, C. M., & Abramovitch, R. (1979). Infants’ tactual discrimination of novel and familiar tactual stimuli. Child Development, 50, 1251-1253. Whitaker, H. A. (1976). Neurobiology of language. In E. R. Carterette & M. P. Friedman (Eds.), Handbook of Perception: Vol. II. New York: Academic Press. Witelson, S. F., & Pallie, W. (1973). Left hemisphere specialization for language in the newborn: Neuroanatomical evidence of asymmetry. Brain, 96, 641-646.
and Racial
in Tactile-Visual in Normal
(Cross-Modal) Black and White
Children Lola 1. Heverly Orlando,
Florida
Walter Isaac
of Georgia
University
George W. Hynd University
of Georgia and Medical College of Georgia
Controversy exists as to when those functions associated with the left tertiary cortex become fully developed in children. To address this issue, neuropsychological development of tactile-visual (cross-modal) discrimination was assessed in 200 normal children aged 5 through 9 years. The factors of gender and race (black, white) were evaluated across this age span. A three-factor ANOVA revealed no gender differences, but signtficant main effects for age and race existed. There were no significant interactions. White children outperformed black children across all ages, and Sheffe’s post-hoc comparisons revealed that, by age 7, children have mastered those basic cross-modal functions necessary for complex higher cognitive processes. The implications of these findings are discussed.
Functional and structural asymmetries in the brain are well documented, and it is assumed that, in terms of the hierarchical organization of the nervous system, the greatest degree of asymmetry is found in those regions
Requests for reprints may be directed to George ogy, 325 Aderhold Hall, University of Georgia,
W. Hynd, Department of Educational Athens, GA, 30602, USA.
139
Psychol-
140
L. L. Heverly,
UT Issac, and G. W Hynd
of the cortex associated with higher cognitive functions (Galaburda & Eidelberg, 1982; Geschwind & Levitsky, 1968; Witelson & Pallie, 1973). In particular, it seems as though the region of the left parietal-occipital cortex is significantly asymmetrical in humans (Hier, LeMay, Rosenberger, & Perlo, 1978) and that this asymmetry is significantly related to cross-modal integrative functioning (e.g., Luria, 1980; Whitaker, 1976). Luria (1980) has suggested that, by age 7, the tertitary cortex has reached sufficient maturity in children to be fully functional in the integration of sensory input from the auditory, somatosensory, and visual cortexes. Evidence does exist suggesting that tactile discrimination develops at an early age (e.g., Soroka, Corter, & Abramovitch, 1979) and that by age 4 most children can integrate and associate visual stimuli with tactile perception (Altman & Bridge, 1968). However, relatively few studies have directly assessed whether tactile-visual cross-modal integration is developed by age 7, as suggested by Luria (1980). Fishbin, Decker, and Wilcox (1977) examined the cross-modal transfer of spatial information, using 48 first-, second-, and fourth-grade males and females. The spatial task required the perception of a group of three geometrical objects. The stimuli were presented either tactilly or visually, and the choice stimuli were photographs of different configurations. Of interest, no difference was found between the intramodal and the cross-modal conditions. Generally, the older children did better on these tasks. In another study of developmental changes in hemispheric specialization for tactile-spatial ability, Flannery and Balling (1979) also found age-related differences. Their subjects included 64 first-, third-, and fifth-grade students, plus a group of adults. Each subject completed 40 trials of exploring nonsense forms using only finger motion. Two conditions were used: In the first condition, the stimulus forms were presented successively to the same hand, and, in the second condition, the stimuli were presented simultaneously to both hands. The subjects were required to determine if the forms were the same or different. The results indicated no significant differences in right-hand-left-hand performance in the first- or third-grade subjects; however, the left hand (right hemisphere) was more accurate in discrimination for the fifth graders and the adults. This indicated an age factor. A sex difference was found only in the adult group, with the male subjects making fewer errors than the female subjects. Finally, it was found that the simultaneous presentation of the two stimuli forms was more difficult than the first condition. In the context of the present investigation one other study deserves mention. Hatta, Yamamoto, Kawabata, and Tsutui (1981) studied hemispheric specialization for tactile recognition in normal children. The subjects were eight boys and eight girls at the second-, fourth-, and sixth-grade levels.
These subjects were required to tactilly explore objects and match each with an analogue object on visual display. The performance of right and left hands was compared. No significant differences were found in second and fourth graders; however, the sixth graders were more accurate at this task with their left hand. Sex differences were noted. Right-hand performance was superior to left in females, but no right-handed-left-handed difference was exhibited in the males’ performance on this task. Consequently, it would appear that older children consistently do better on cross-modal tasks involving tactile-visual integration, but, according to various studies, there is variability as to when this skill reaches full maturity. Also, although sex differences appear to exist, they are found inconsistently. In the Hatta et al. (1981) study, females showed a hand preference, whereas, in the Flannery and Balling (1979) study, males did better than females. To date, no study has evaluated right-hand tactile-visual integration in a developmental population incorporating race and gender as major factors. Presumably, right-hand performance reflects the functioning of the left tertiary cortex in cross-modal integration and thus allows for a more objective evaluation of Luria’s (1980) hypothesis.
Subjects
This study included a sample of 200 average-functioning, right-handed children from a South Carolina school district of approximately 50,000 students. The sample was composed of 40 children at each age level from the ages of S through 9, Each group of 40 children at the five age levels examined comprised 20 males and 20 females. Each of these gender groups included 10 white and 10 black children. All subjects were previously familiarized with the examiner, and the subject population included only those normal children who had not been referred for special services. All children had normal vision and hearing. Measure
The instrument designed to assess stereognosis as used in this study consisted of a box into which the child could reach through a sleeve to feel various geometric shapes without visual input. Two sets of identical threedimensional wooden shapes were devised. Each set consisted of nine shapes. These shapes were cut from an 8.35 cm block and painted white. The shapes included a circle, a square, a triangle, an octagon, a cross, a six-pointed star, a five-pointed star, a small diamond, and a large diamond.
L. L. Heverly, W Issac, and G. W Hynd
142
Procedure Each child was asked to reach into the box with her or his right hand and to explore tactilly the geometric shape placed in her or his palm. The child was then required to select the same shape from an alternative set of blocks placed before her or him by pointing with the left hand. There was no time limit, and, if the child responded verbally, she or he was requested to point to her or his selection. The order of presentation of the nine geometric shapes was determined by a table of random numbers. The set of nine shapes was presented for three consecutive trials, with each trial randomly ordered. Thus, a total of 27 presentations was possible. Each of the responses. was scored as either correct or incorrect. The total possible score was a maximum of 27 correct choices. Data Analysis A 5 (age) x 2 (sex) x 2 (race) analysis of variance (ANOVA) was used to evaluate the data. Because all were independent measures, a single withingroups error term was used. Sheffe’s (Keppel, 1982) post-hoc comparisons of the age means was then computed. RESULTS Table 1 presents the means and standard deviations for all factors. Although no significant effect was found for gender, F( 1, 180) = 2.47, p > .05, there was, as expected, a significant effect for age, F(4, 180) = 22.43, p < .Ol. TABLE 1 Means and Standard Deviations by Age Groups for Black and White Children Age 5-o
to 5-11
6-O to 6-11 7-o to 7-11 8-O to 8-l 1 9-o to 9-11
Race
N
Mean
Standard Deviation
White Black White Black White Black White Black White Black
20 20 20 20 20 20 20 20 20 20
18.00 16.35 21.20 19.35 22.40 22.10 23.25 22.35 23.50 22.65
4.64 3.91
3.20 4.41 3.20 2.23 2.68 3.04 1.96 2.72
Note. The 20 subjects for each racial group consisted of 10 males and 10 females.
Neurodevelopmental
Changes
I43
Also, a significant effect was found for race, F( 1,180) = 5.70, p < .05. The white subjects were found to perform significantly better on this task than the black subjects. None of the two- or three-way interactions was statistically significant (p > .05). These results support previous research, which has indicated an increase in accuracy of performance on tactile-visual cross-modality functioning in normally developing children as they get older (Flannery & Balling, 1979). Sheffe’s comparison of means was used to determine if there were significant differences among the age levels. This procedure indicated that the j-yearold subjects performed significantly differently from the older age groups, F(4,180) = 17.81, pc .Ol. This showed that all of the older children performed significantly better on this task than the 5-year-olds. The 6-year-old subjects did not perform significantly differently from the 7-year-olds, F(4,180) = 7.23, p > .Ol. However, they did perform significantly differently from the 8-year-old group, F(4,180) = 8.12, p< .05, and from the 9-year-old group, F(4,180) = 14.53, p< .Ol. This indicated that the S- and g-year-old subjects performed significantly better than the 6-year-old subjects. No other significant differences (pc .05) were found among the age groups, indicating that the 7-, 8-, and 9-year-old subjects performed similarly. In summary, on this tactile-visual cross-modality task, no difference in male-female performance was found. As predicted, significant differences were found among the age groups, with older children performing significantly better than younger children. Unique to this investigation, and a finding not reported elsewhere, is the fact that black children consistently did more poorly in cross-modal tactile-visual recognition than the white children across all ages from 5 through 9. DISCUSSION
The results of this study support the notion that patterns of parietal-lobe function improve with age in children. In the groups studied, ages 5 through 9, increasing accuracy on the tactile-visual task was evident with age, and significant differences were found between the age groups. Five-year-olds performed significantly less accurately than all the other groups of children. No significant difference was found between 6- and 7-year-olds; however, 6year-olds performed significantly less accurately than 8- and 9-year-olds. No significant differences were found among the 7-, 8-, and 9-year-old age groups. Luria (1973) stated that the tertiary zones of the parietal lobe do not become fully operative until 7 years of age. The findings of this study lend objective developmental evidence to Luria’s hypothesis. It is important that the finding that racial differences exist on this task involving cross-modal integration lends increasing support to a growing body of literature that
144
L. L. Heverly,
W Issac, and G. W Hynd
indicates the importance of culture on the development of neuropsychological abilities (e.g., Albert & Obler, 1978; Hynd, Teeter, & Stewart, 1980). In addition to adding support to the findings of Flannery and Balling (1979), these results relate to those reported by Satz and his coheagues (Satz, Taylor, Friel, & Fletcher, 1978). Based on the premise that children who are delayed in perceptual-motor development and cross-modal sensory integration will also be delayed in learning to read, Satz assessed the predictive validity of a number of measures in a large-scale longitudinal study. Having assessed them in kindergarten and followed them through the fifth grade, Satz found that three of the five overall best predictors of reading failure were associated with tactile-visual functioning (finger localization, the Beery Visual-Motor Integration Test, and a visual-recognition task). Thus, in terms of neurodevelopmental processes important in the acquisition of prerequisite reading skills, those associated with cross-modal sensory integration are vitally important. It is in this regard that the present study is relevant. Those basic crossmodal integrative skills associated with the left tertiary cortex seem fully developed by age 7, when most normal children are developing an essential comprehension of the reading process using primarily visuo-spatial or orthographic attributes of memory (Hynd & Obrzut, 1977). The racial differences found in this study warrant further evaluation. They also call into question the applicability of norms developed for neuropsychological tests, in which potential racial differences are not considered across developmental levels. Clearly, the effect of culture or ethnic group in the development of neuropsychological abilities is not yet well defined. If the tasks used in this study are reflective of neurodevelopmental process associated with left tertiary cortex functioning, then do they suggest delay of important basic integrative process? Also, is there some point at which black children reach the level of functioning of white children, and what predictive effect might thus exist across age groups according to ethnic group? Further study seems indicated to address these and related issues regarding the development of neuropsychological process in normal children.
REFERENCES Albert,
M. L., & Obler, L. K. (1978). The 6ifi~g~u~ brain. New York: Academic
fliank, M., Attman, & Bridger (1968). Cross-modal transfer school children. fsychonomic Science, 10, 5 l-52. Fishbein, H., Decker, J., & Wilcox, P. (1977). Cross-modality
of form transfer
Press.
discrimination of spatial
in pre-
information.
British Journal of Psychology, 68, 503-508. Flannery, R. C., & Balling, J. D. (1979). Developmental changes in hemispheric specialization for tactile spatial ability. Developmenta/ Psycho/ogy, 15. 364-372. Galaburda, A. M., & Eidelberg, D. (1982). Symmetry and asymmetry in the human posterior
Neurodevelopmental
Changes
145
thalamus: II. Thalamic lesions in a case of developmental dyslexia. Archives of Neurology, 39, 333-336. Geschwind, N., & Levitsky, W. (1968). Left-right asymmetries in temporal speech region. Science, 161, 186-187. Hatta, T., Yamamoto, M., Kawabata, Y., & Tsutui, K. (1981). Development of hemisphere specialization for tactile recognition in normal children. Cortex, 17, 611-616. dyslexia: Hier, D. B., LeMay, M., Rosenberger, x., & Perlo, V. P. (1978). Developmental Subgroup with a reversal of cerebral asymmetry. Archives of Neurology, 35, 90-92. Hynd, Cl. W., & Obrzut, J. E. (1977). Developmental shift hypothesis and preferred memory attributes in elementary school children. Perceptuul and Motor Skills, 46, 167-170. Hynd, G. W., Teeter, A., & Stewart, J. (1980). Acculturation and the lateralization of speech in bilingual Native Americans. International Journal of Neuroscience, 11, 1-7. Keppel, G. (1982). Design and analysis: A researcher’s handbook (2nd ed.). New Jersey: Prentice-Hall. Luria, A. R. (1973). The working brain: An introduction to neuropsychology. New York: Basic Books. Luria, A. R. (1980). Higher corticulfunctions in man. New York: Basic Books. Satz, P., Taylor, H. G., Friel, J., & Fletcher, J. M. (1978). Some developmental and predictive precursors of reading disabilities: A six year follow-up. In A. L. Benton & D. Pearl (Eds.), Dyslexia: An appraisal of current knowledge. New York: Oxford University Press. Soroka, S. M., Corter, C. M., & Abramovitch, R. (1979). Infants’ tactual discrimination of novel and familiar tactual stimuli. Child Development, 50, 1251-1253. Whitaker, H. A. (1976). Neurobiology of language. In E. R. Carterette & M. P. Friedman (Eds.), Handbook of Perception: Vol. II. New York: Academic Press. Witelson, S. F., & Pallie, W. (1973). Left hemisphere specialization for language in the newborn: Neuroanatomical evidence of asymmetry. Brain, 96, 641-646.