Neuropsychologia,1975,Vol. 13,pp. 103to
105. Pergamon
Press. Printed in England.
NOTE! CEREBRAL SPEECH LATERALIZATION DIANA
Psychology Department,
1N YOUNG CHILDREN*
INGRAM
University of Western Ontario, London, Canada (Received
2 April 1974)
Abstract-A right ear superiority was found on a dichotic listening task as early as age three, suggesting that the left hemisphere is to some extent specialized for speech functions by this age. THE DICHOTIC listening
task has been found to be a good indicator of cerebral speech lateralization, so that when words are presented simultaneously to both ears, more words are reported for the ear opposite the hemisphere dominant for speech [l]. Using this technique, a right-ear superiority, and presumably left hemisphere dominance for speech, has been found as early as age three in Japanese children [2], and age four in Canadian children [3]. However, these findings are somewhat tentative in view of reports that children from low socio-economic areas may not develop a right-ear superiority until as late as age six [4], or seven [5]. Accordingly, it was of interest to report more normative data on the development of speech lateralization in young children. METHOD The subjects were 84 right-handed children (14 boys and 14 girls at ages three, four and five) who took part in a study of motor asymmetries [6]. Eighty of the children were tested at five day care centres in the London area, and four of the three-year-olds were tested at the University of Western Ontario. The children came from a variety of socio-economic backgrounds, chiefly non-professional, and were selected only on the basis of age, sex and normal hearing. The dichotic stimuli were presented from a Tandberg tape recorder (Series 6X), by means of stereophonic earphones (Steintron STH-3X). The position of the earphones was counterbalanced over ears within each age and sex group. The tape itself had been specially modified for young children [7], and consisted of two subtests: Pointing-to-pictures, and Placing-objects-on-pictures. No practice trials were given for either part of the tape, because before starting the test, the examiner made sure the child understood the instructions and would respond appropriately. The maximum score possible per ear was 27. RESULTS A 3 x 2 x 2 analysis of variance was computed on the data. The factors analysed were age (three, four and five), sex (male, female), and ear (left, right). The ear factor was a repeated measure. Although mean scores are expressed as percentages, all analyses were carried out on the raw data. Words arriving at the right ear (mean=59.3 % correct) were reported more accurately than words arriving at the left ear (mean=37.0% correct) (F=4521, df=1,78, P
105. Pergamon
Press. Printed in England.
NOTE! CEREBRAL SPEECH LATERALIZATION DIANA
Psychology Department,
1N YOUNG CHILDREN*
INGRAM
University of Western Ontario, London, Canada (Received
2 April 1974)
Abstract-A right ear superiority was found on a dichotic listening task as early as age three, suggesting that the left hemisphere is to some extent specialized for speech functions by this age. THE DICHOTIC listening
task has been found to be a good indicator of cerebral speech lateralization, so that when words are presented simultaneously to both ears, more words are reported for the ear opposite the hemisphere dominant for speech [l]. Using this technique, a right-ear superiority, and presumably left hemisphere dominance for speech, has been found as early as age three in Japanese children [2], and age four in Canadian children [3]. However, these findings are somewhat tentative in view of reports that children from low socio-economic areas may not develop a right-ear superiority until as late as age six [4], or seven [5]. Accordingly, it was of interest to report more normative data on the development of speech lateralization in young children. METHOD The subjects were 84 right-handed children (14 boys and 14 girls at ages three, four and five) who took part in a study of motor asymmetries [6]. Eighty of the children were tested at five day care centres in the London area, and four of the three-year-olds were tested at the University of Western Ontario. The children came from a variety of socio-economic backgrounds, chiefly non-professional, and were selected only on the basis of age, sex and normal hearing. The dichotic stimuli were presented from a Tandberg tape recorder (Series 6X), by means of stereophonic earphones (Steintron STH-3X). The position of the earphones was counterbalanced over ears within each age and sex group. The tape itself had been specially modified for young children [7], and consisted of two subtests: Pointing-to-pictures, and Placing-objects-on-pictures. No practice trials were given for either part of the tape, because before starting the test, the examiner made sure the child understood the instructions and would respond appropriately. The maximum score possible per ear was 27. RESULTS A 3 x 2 x 2 analysis of variance was computed on the data. The factors analysed were age (three, four and five), sex (male, female), and ear (left, right). The ear factor was a repeated measure. Although mean scores are expressed as percentages, all analyses were carried out on the raw data. Words arriving at the right ear (mean=59.3 % correct) were reported more accurately than words arriving at the left ear (mean=37.0% correct) (F=4521, df=1,78, P
