Global perception of small numerosities (subitizing) in cerebral-palsied children.

The goal of this study was to investigate how global perception of small numerosities (subitizing) develops in cerebral-palsied children (CP), as compared to control children. Twenty-nine 4- to 8-year-old CP children were compared to controls matched on age and sex. Both groups were asked to quantify sets of one to six items displayed briefly on a screen (250 ms). The children were also assessed on counting and eye-hand coordination. CP children exhibited a lower subitizing limit than control children. In CP and control children, the subitizing limit increased significantly with age. In CP children, the subitizing limit was positively correlated with counting performance, and both were positively correlated with eye-hand coordination. In addition, the subitizing limit in CP children with no evidence of a right-hemisphere lesion tended to be higher than in children with a right or bilateral lesion, suggesting right-hemisphere involvement in subitizing. These results support the idea that subitizing and counting are not independent processes during development, and argue in favor of a model of subitizing that relies on a global process.