The Frequency Doubling Illusion and Testing of Magnocellular Sensitivity

Abstract

The frequency doubling illusion has been claimed to be a useful test of magnocellular integrity. This claim is examined. It is found that since the temporal frequency of the stimuli is very high, it is plausible that they are detected by magnocellular neurons. This, however, does not make frequency doubling by itself into an appropriate test of magnocellular sensitivity. This is because it involves testing sensitivity under only one stimulus condition and so does not allow magnocellular deficits to be differentiated from general visual impairments. Further limitations on the use of the frequency doubling illusion to assess magnocellular sensitivity are also discussed.