Comparative study of laterality in people with fragile X syndrome,people with intellectual disabilities,and people with typical development

Following on from the studies by McManus and Cornish [(1997). Fractionating handedness in mental retardation: What is the role of the cerebellum? Laterality, 2(2), 81–89] and Cornish, Pigram, and Shaw [(1997). Do anomalies of handedness exist in children with fragile-X syndrome? Laterality, 2(2), 91–101], the aim of this paper was to determine laterality in people with fragile X syndrome (FXS). The sample comprised three study groups: the first with 30 people with FXS (mean age 17.9 years), the second 34 people with various intellectual disabilities (ID, mean age 20.9 years), and the third 160 people with typical development (mean age 14.7 years). Laterality was assessed with a test adapted for this study. The results confirm the preponderance of right-handedness (93.3%) in people with FXS and present new data regarding footedness and sensory dominance (eyedness and earedness), indicating inconsistent footedness and ocular cross-dominance. Almost three-quarters (73.5%) of people with other ID were right-handed. The results corroborate those of McManus and Cornish (1997). People with FXS tend to be right-handed but have ocular cross-dominance.