Dichotic-listening performance following auditory discrimination training in Down's syndrome and developmentally retarded children.

The ear advantages of groups of Down's syndrome, developmentally retarded (aetiology of retardation unknown) and normal children were compared for repeated administrations of a dichotic word test both before and following auditory discrimination training. Training involved words from the dichotic test. The developmentally retarded and normal groups showed the expected right ear advantage, whereas the Down's syndrome group showed an advantage favouring the left ear. However, ear advantages regardless of their direction were of a similar order for the three groups and, further, were stronger for tests which followed training. These results suggest atypical right hemisphere representation of speech perception for Down's syndrome but not for developmentally retarded children.