Line drawing as a possible measure of lateralized motor performance in schizophrenia

In this paper we suggest a new method, conceived by Maher, to assess lateralized motor performance in schizophrenia. Subjects draw two straight lines with each hand. The lines are scanned into a computer, and a regression is run on the points of the line. The root mean squared error (RMS) of the regression equation indicates the deviation from straightness of the line. The average RMS of all four lines is taken as an overall measure of motor disorder, and the difference in performance between the two hands serves as an index of motoric laterality. Scores on the motor disorder index were significantly positively related to clinical ratings of Parkinsonism among schizophrenic inpatients. A marginal relation was found to ratings of voluntary movement disorders, and the task was not associated with dyskinetic movements. Scores on the motor disorder measure were significantly worse for schizophrenic subjects than for staff controls. The laterality index significantly differentiated right- and left-handed subjects, but did not differentiate schizophrenic from control subjects. Maher's simple line drawing task yields objective continuous ratings of motor disorder and handedness and may be a useful tool for examining associations between motor functioning and cognition and symptomatology in schizophrenia.