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Abstract: The purpose of this study is to investigate the handedness of menta-lly retarded children and the relationship between handedness and thecerebral lateralization. 100 mentally retarded children(2-12 years of age)participated in this study. The results show: (1) there is a high-left-handedness phenomenon(ormixed handedness)in mentally retarded childrei. The average ratio of thefrequency of left hand and right hand in giasping behavior of these sub-jects in four experiments was nearly 1:2, very similar to the same ratioof 1-2-year-old normal children's level; (2) sex and age had no significant-influence upon the handedness of retarded children; (3) the level ofretardation is significantly related with handedness. The ratio of the fre-quency of left hand and right hand of mildly retarded children in gras-ping behavior is bigger than that of the same ratio of moderately and se-verely retarded children (4) the cues, which mentally retarded childrenused in grasping objects were different in four experiments: in experime-nts Ⅰ to Ⅲ, position(closeness of hand)was the main cue while in experi-ment Ⅳ, preference, not position, was the main cue: (5) there is a directrelationship between the mixed handedness and the lack of cerebral la-teral specialization or the poor cerebral dominance. This remains an openquestion

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