Two disadvantages of a television system as pattern stimulator for evoked potentials

The use of television systems to generate patterned stimuli for the examination of EPs has disadvantages due to the frame frequency of 50Hz of television sets. Because of this, changes in the pattern last 20 msec, with the result that the variability in EP latencies is larger than in the results obtained by projector systems. Furthermore, 50 Hz noise on the recordings, transmitter through the visual system, may be seen.