Hemispheric specialization in children as reflected in the longitudinal development of ear asymmetry

The longitudinal development of ear asymmetry has been investigated in two samples of kindergarten and primary school children over an age range of six years. Ear preference in a dichotic digit test, administered four times, did not appear to be affected by age and sex: right ear advantage was predominant at all times. Individual comparison showed the development of ear advantage to depend on initial preference. Initially left eared subjects when changing ear advantage do so from left to right at early and from right to left at later school ages. The left-right shift may be due to the school teaching of linguistic skills which could selectively activate the left cerebral hemisphere. This explanation is supported by the finding that initially right eared subjects tended to conserve that preference at early school ages. Acknowledgements. We would like to thank Mr. P. Borgman and his staff of the Johannesschool in Amsterdam as well as their pupils who did not protest despite being examined year after year. The cooperation of the Free University Audio-Visual Center (Mr. Fred Van Hilst) is kindly acknowledged. Finally we would like to thank Dr. Paul Harris who was willing to read the English text critically and all others who assisted in the completion of this research.