DETECTION OF EMG ONSET IN ERP RESEARCH

Many researchers have used off-line techniques for the automatic detec tion of electromyogram (EMG) onset. However, very little is known abou t the accuracy of these methods. In the present study, five such metho ds are evaluated and their accuracy is reported. Five subjects were as ked to produce fast (ballistic) and slow (ramp) contractions with thum b and index finger of the right hand in a simple reaction time task. E MG was recorded from the first dorsal interosseus muscle, and onsets w ere visually determined in the raw EMG. These onsets were compared wit h the onsets produced by the automated methods on the rectified and lo w-pass filtered EMG. Four of the automated methods produced very relia ble estimates of the visually determined onsets, at least when additio nal constraints upon the initial estimates were made. Studies using au tomated methods for EMG onset detection should report findings about t heir accuracy.