Simultaneous Changes in Visual Separation Threshold and Voltage of Corfical Alpha Rhythm

An automated psychophysical method allows a human subject to track his own separation threshold for two flashes delivered in sequence without interfering with the simultaneous recording of the alpha rhythm of his electroencephalogram. A systematic rise in this threshold is observed when the alpha voltage declines from its normal alert level. This suggests that an increase in the minimum resolvable temporal sequence may contribute to the development of the negative time errors associated with drowsiness and sleep.