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Frequency of cerebral lateral dominance variations among school children of premature and full-term birth
FREQUENCY OF CEREBRAL LATERAL DOMINANCE VARIATIONS AMONG SCHOOL C H I L D R E N OF PR E M AT U RE AND FULL-TERM BIRTH
THOMASH. EAMES, ED.M., M.D. BOSTON, MASS. HI S study of birth weight and cerebral lateral dominance (or sidedness) was made in connection with a long-term investigation of the effects of premature birth on children of school age. Previous findings are at variance with tile commonly held belief that the handicap of premature birth is largely overcome by the time a child is ready to enter school. An early report showed more neurological lesions, defective vision, slow speeds of visual perception, certain lateral dominance variations, and a higher incidence of reading failure among children of premature birth than in a nonpremature group of school children. 1 A later study compared 155 children of school ages who weighed 5.5 pounds or less at birth with 439 of comparable ages with birth weights over 5.5 pounds (considered full term). The findings disclosed a higher percentage of vision below 20/20 among the premature subjects and a higher "average" (median) degree of subnormal vision at all ages from 5 through 9 years. 2 F u r t h e r investigation revealed a tendency for birth weight, visual acuity, and the speeds of object and word perception to exhibit a higher correspondence in a group whose members weighed less than 5.5 pounds
T
at birth than among those whose birth weights were over 5.5 pounds. 3 The present study was made because of the controversial position of lateral cerebral dominance of eye and hand in the etiology, diagnosis, and treatment of language disabilities, particularly in the fields of speech, reading, writing, and spelling. For example, it is often alleged that lateral cerebral dominance variations (such as dominance of the nonpreferred hand, uncertain dominance, or confused dominance) are likely to be associated with speech difficulties, particularly with delayed speech and stuttering, while sinistrality has been blamed for reversal tendencies in reading and writing, in which "b" becomes "d," "saw"--"was," and "dog"--"god," as well as the tendency to t ry to read from right to ]eft. Confused and uncertain dominance of both eye and hand or either have been coupled with reading, writing, and spelling failure as an explanation of such common errors as reversals, regressions, confusions, defects of orientation, and the like. Some believe that lateral cerebral dominance variations produce language difficulties through defective integration in the dominant half of the cortex as a result of some dysfunction of the thalamus, cerebellum, or the nondominant hemisphere. 4
300
EAMES:
:~'REQUENCY OF CEREBRAL LATERAL D O M I N A N C E YARIATIONS
Five hundred ease records were reviewed, of which fifty-three were disqualified because of questionable test results or recording, leaving 447 cases. Forty-three of them (9.6 per cent) had birth weights of 5.5 pounds or less (premature group) and 404 had birth weights of more than 5.5 pounds. The age range was from 5 through 17 years.
Each child in the study had been given ring and aiming tests of eyedhess, and throwing and reaching tests of handedness. Other, supplementary tests of both eyedness and handedness were used in almost every ease, although there was some variation in the number of supplementary tests used and in the selection of those which were used as supplements. The categories of cerebral lateral dominance studied included the following: right eyedness with right handedness (deemed normal), left eyedness with left handedness, right eyedness with left handedness, left eyedness with right handedness, ampbioeularity with right handedness, amphiocularity with left handedness, right eyedness with ambidexterity, left eyedness with ambidexterity, and amphiocularity with ambidexterity. The cases falling in each of the categories were distributed by birth weight, and the frequency of each combination of cerebral lateral dotal nanee was determined and recorded. The entire group was subdivided at the 5.5 pound birth weight line, with those with birth weights of 5.5 pounds or less forming the " ' p r e m a t u r e " group and the others the " f u l l - t e r m " group. A comparison of the frequency of each of the cerebral lateral dominance variations in these two groups showed
301
20 per cent more of the combinations other than right eyedness with right handedness among the " p r e m a t u r e " group, the frequency of such variations being 74 per cent among the " p r c m a t u r e s " and 54 per cent among the " f u l l terms." It is sometimes argued that left eyedness with left handedness is really a normal situation to the extent that both eyedness and handedness controls are on the same side of the brain. With this in mind, the frequency of combinations other than right eyedness with right handedness and left eyedness with left handedness was determined. The " p r e m a t u r e " group exhibited 10 per cent more of these variations, their frequency being 57 per cent, while that of the " f u l l t e r m s " was 47 per cent. Although it is possible that we should regard left eyedness with left handedness as " n o r m a l , " it should be pointed out that this condition is opposed (in theory at least) to the leftto-right approach to reading, writing, and spelling which is characteristic of our culture, and that some have attributed mirror writing and reversals of various kinds to extreme sinistrality. I am inclined to feel that left eyedhess with left handedness is probably as important as any of the combinations other than right eyedness with right handedness, since it may tend to oppose the cultural tendency. F u r t h e r comparison of t l l e t w o groups revealed that several combinations occurred more frequently among the "prematures"; specifically, left eyedness with left handedness was 10 per cent more frequent there than in the " f u l l - t e r m " groups, left eyedness
302
THE JOURNAL OF PEDIATRICS
with right handedness 8 per cent, amphiocularity with right handedness 8 per cent, amphiocularity with left eyedness 3 per cent, and amphiocu]arity with ambidexterity 1 per cent. Conditions occurring less frequently among the "prematures," with the percentage differences, included right eyedness with right handedness 20 per cent less frequent, right eyedness with ]eft handedness 6 per cent, right eyedhess with ambidexterity 2 per cent, and left eyedness with ambidexterity 2 per cent. To the extent that this study is representative, it seems safe to conclude that lateral cerebral dominance variations other than right eyedness with right handedness occur more frequently among the ' ' prematures," except for right eyedness w i t h l e f t handedness, right eyedness with ambidexterity, and left eyedness with ambidexterity. The degree to which variations in lateral cerebral dominance may interfere with language hmetion, t h e mechanism of such impediment, the frequency of its participation as a factor in the etiology of language failure or defect, and individual differences in response to handicaps of the kind
remain to be determined and appear to be a knotty neurological problem. SUre, MARY
Forty-three children between the ages of 5 and 17, whose birth weights were 5.5 pounds or less were compared with 404 of comparable age whose birth weights were over 5.5 pounds. The " p r e m a t u r e " group presented 20 per cent more lateral cerebral dominance variations from the " n o r m a l " right eyedness with right handedness: higher frequencies of left eyedness with left handedness, left eyedness with right handedness, amphiocularity with right handedness, amphiocularity with left eyedness, and amphiocularity with ambidexterity. RE~ER~ENCES 1. Eames, T. I t . : Comparison oT Children of Premature and Full Term B i r t h Who Fail in Reading, J. Ed. Res. 38: 506, 1945. 2. Eames, T. ~I.: Eye Conditions Among Children of Premature, Full Term and Hypermature Birth, Am. J. Ophth. 29: 57, 1946. 3. E~mes, T. H.: The Relationship of B i r t h Weight, the Speeds of Object and Word Perception and Visual Acuity, J. PEDIAT. 471 603, 1955. 4. Van Riper, C.: Speech Correction~ ed. 2, New York, :1949, Prentice-Hall, Inc., p. 268.
THOMASH. EAMES, ED.M., M.D. BOSTON, MASS. HI S study of birth weight and cerebral lateral dominance (or sidedness) was made in connection with a long-term investigation of the effects of premature birth on children of school age. Previous findings are at variance with tile commonly held belief that the handicap of premature birth is largely overcome by the time a child is ready to enter school. An early report showed more neurological lesions, defective vision, slow speeds of visual perception, certain lateral dominance variations, and a higher incidence of reading failure among children of premature birth than in a nonpremature group of school children. 1 A later study compared 155 children of school ages who weighed 5.5 pounds or less at birth with 439 of comparable ages with birth weights over 5.5 pounds (considered full term). The findings disclosed a higher percentage of vision below 20/20 among the premature subjects and a higher "average" (median) degree of subnormal vision at all ages from 5 through 9 years. 2 F u r t h e r investigation revealed a tendency for birth weight, visual acuity, and the speeds of object and word perception to exhibit a higher correspondence in a group whose members weighed less than 5.5 pounds
T
at birth than among those whose birth weights were over 5.5 pounds. 3 The present study was made because of the controversial position of lateral cerebral dominance of eye and hand in the etiology, diagnosis, and treatment of language disabilities, particularly in the fields of speech, reading, writing, and spelling. For example, it is often alleged that lateral cerebral dominance variations (such as dominance of the nonpreferred hand, uncertain dominance, or confused dominance) are likely to be associated with speech difficulties, particularly with delayed speech and stuttering, while sinistrality has been blamed for reversal tendencies in reading and writing, in which "b" becomes "d," "saw"--"was," and "dog"--"god," as well as the tendency to t ry to read from right to ]eft. Confused and uncertain dominance of both eye and hand or either have been coupled with reading, writing, and spelling failure as an explanation of such common errors as reversals, regressions, confusions, defects of orientation, and the like. Some believe that lateral cerebral dominance variations produce language difficulties through defective integration in the dominant half of the cortex as a result of some dysfunction of the thalamus, cerebellum, or the nondominant hemisphere. 4
300
EAMES:
:~'REQUENCY OF CEREBRAL LATERAL D O M I N A N C E YARIATIONS
Five hundred ease records were reviewed, of which fifty-three were disqualified because of questionable test results or recording, leaving 447 cases. Forty-three of them (9.6 per cent) had birth weights of 5.5 pounds or less (premature group) and 404 had birth weights of more than 5.5 pounds. The age range was from 5 through 17 years.
Each child in the study had been given ring and aiming tests of eyedhess, and throwing and reaching tests of handedness. Other, supplementary tests of both eyedness and handedness were used in almost every ease, although there was some variation in the number of supplementary tests used and in the selection of those which were used as supplements. The categories of cerebral lateral dominance studied included the following: right eyedness with right handedness (deemed normal), left eyedness with left handedness, right eyedness with left handedness, left eyedness with right handedness, ampbioeularity with right handedness, amphiocularity with left handedness, right eyedness with ambidexterity, left eyedness with ambidexterity, and amphiocularity with ambidexterity. The cases falling in each of the categories were distributed by birth weight, and the frequency of each combination of cerebral lateral dotal nanee was determined and recorded. The entire group was subdivided at the 5.5 pound birth weight line, with those with birth weights of 5.5 pounds or less forming the " ' p r e m a t u r e " group and the others the " f u l l - t e r m " group. A comparison of the frequency of each of the cerebral lateral dominance variations in these two groups showed
301
20 per cent more of the combinations other than right eyedness with right handedness among the " p r e m a t u r e " group, the frequency of such variations being 74 per cent among the " p r c m a t u r e s " and 54 per cent among the " f u l l terms." It is sometimes argued that left eyedness with left handedness is really a normal situation to the extent that both eyedness and handedness controls are on the same side of the brain. With this in mind, the frequency of combinations other than right eyedness with right handedness and left eyedness with left handedness was determined. The " p r e m a t u r e " group exhibited 10 per cent more of these variations, their frequency being 57 per cent, while that of the " f u l l t e r m s " was 47 per cent. Although it is possible that we should regard left eyedness with left handedness as " n o r m a l , " it should be pointed out that this condition is opposed (in theory at least) to the leftto-right approach to reading, writing, and spelling which is characteristic of our culture, and that some have attributed mirror writing and reversals of various kinds to extreme sinistrality. I am inclined to feel that left eyedhess with left handedness is probably as important as any of the combinations other than right eyedness with right handedness, since it may tend to oppose the cultural tendency. F u r t h e r comparison of t l l e t w o groups revealed that several combinations occurred more frequently among the "prematures"; specifically, left eyedness with left handedness was 10 per cent more frequent there than in the " f u l l - t e r m " groups, left eyedness
302
THE JOURNAL OF PEDIATRICS
with right handedness 8 per cent, amphiocularity with right handedness 8 per cent, amphiocularity with left eyedness 3 per cent, and amphiocu]arity with ambidexterity 1 per cent. Conditions occurring less frequently among the "prematures," with the percentage differences, included right eyedness with right handedness 20 per cent less frequent, right eyedness with ]eft handedness 6 per cent, right eyedhess with ambidexterity 2 per cent, and left eyedness with ambidexterity 2 per cent. To the extent that this study is representative, it seems safe to conclude that lateral cerebral dominance variations other than right eyedness with right handedness occur more frequently among the ' ' prematures," except for right eyedness w i t h l e f t handedness, right eyedness with ambidexterity, and left eyedness with ambidexterity. The degree to which variations in lateral cerebral dominance may interfere with language hmetion, t h e mechanism of such impediment, the frequency of its participation as a factor in the etiology of language failure or defect, and individual differences in response to handicaps of the kind
remain to be determined and appear to be a knotty neurological problem. SUre, MARY
Forty-three children between the ages of 5 and 17, whose birth weights were 5.5 pounds or less were compared with 404 of comparable age whose birth weights were over 5.5 pounds. The " p r e m a t u r e " group presented 20 per cent more lateral cerebral dominance variations from the " n o r m a l " right eyedness with right handedness: higher frequencies of left eyedness with left handedness, left eyedness with right handedness, amphiocularity with right handedness, amphiocularity with left eyedness, and amphiocularity with ambidexterity. RE~ER~ENCES 1. Eames, T. I t . : Comparison oT Children of Premature and Full Term B i r t h Who Fail in Reading, J. Ed. Res. 38: 506, 1945. 2. Eames, T. ~I.: Eye Conditions Among Children of Premature, Full Term and Hypermature Birth, Am. J. Ophth. 29: 57, 1946. 3. E~mes, T. H.: The Relationship of B i r t h Weight, the Speeds of Object and Word Perception and Visual Acuity, J. PEDIAT. 471 603, 1955. 4. Van Riper, C.: Speech Correction~ ed. 2, New York, :1949, Prentice-Hall, Inc., p. 268.