Upper and Lower Extremity Midline Crossing Effects Upon Adults with Mild to Moderate Mental Retardation


Evidence that individuals with mental retardation exhibit midline crossing problems is available. The purpose of this study was to determine if midline crossing inhibition (MCI) was present in individuals with mild to moderate mental retardation (MMR) when crossing the midline of the body with both the upper and lower extremities. Whether MCI was more evident when the individual used the nonpreferred extremity rather than the preferred extremity was also investigated. Thirteen adults with MMR performed a choice reaction time (CRT) and movement time (MT) task using an MCI assessment method designed by Eason and Surburg (1993). Measurement of CRT and MT were recorded as participants performed contralateral, midline, and ipsilateral movements. The premise behind this method was that contralateral movement constituted a more complex task, therefore, requiring more processing time. Multivariate analysis of variance and subsequent analyses revealed that adults with MMR exhibited MCI with both the upper and lower extremities. In addition, MCI was most evident when using the preferred extremities, which suggested a side preference in performing motor tasks. Detection of MCI can serve as the basis for job training leaders and employers to develop strategies which can remedy problems in the workplace that may be caused by this inhibition.

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Education and Training in Mental Retardation and Developmental Disabilities