Two separate experiments were conducted to study the visual evoked potential (VEP) correlates of sequential blanking, a phenomenon in which up to one-half of a discrete train of stimulus inputs are not perceived for certain orders of input. A PDP-7 digital computer was used to present stimuli (from 2 to 5 letter Xs) on a CRT display in both experiments. In Experiment 1 there were four basic conditions designed and counterbalanced to indicate the nature of the YEP when stimuli were blanked and when Ss reported all stimuli. All of the stimuli were of equal intensity. The main finding was that although the eight Ss did not perceive and report blanked stimuli, they did respond to them physiologically as indicated by the YEP. The implications of these findings were discussed in relation to recent studies of visual masking and metacontrast in which YEP was recorded. In Experiment 2 the normally blanked and the normally blanking stimuli were alternately increased in intensity to determine the effect on sequential blanking and the YEP. Six Ss were tested under three basic counterbalanced conditions. It was found that sequential blanking could be reliably overcome by increasing the intensity of the normally blanked stimuli. In addition, when the normally blanking stimuli were of greater intensity than the blanked stimuli, not only did perceptual suppression occur, but the evidence indicated that there was no YEP to the first of the two blanked stimuli.The phenomenon of sequential blanking has been thoroughly described by Mayzner, Tresselt, and Helfer (1967) and further elaborated upon by Mayzner and Tresselt (1970). Briefly, sequential blanking refers to the finding that if a discrete train of stimuli, occurring in different spatial locations on the display surface of a CRT console, are presented sequentially at certain critical input rates, approximately one-half of these stimuli are not perceived. The object of the present experiment was to determine the nature of visual evoked potentials (VEPs) under conditions in which Ss sawall of the stimuli and when some stimuli were blanked.There have been several studies which have explored the YEP correlates of phenomena such as metacontrast and visual masking (Schiller & Chorover, 1966;Vaughan & Silverstein, 1968;Donchin, Wicke, & Lindsley, 1963;Donchin & Lindsley, 1965). Schiller and Chorover (1966) Wicke, and Lindsley (1963) studied VEPs under the visual masking paradigm in which the second, brighter flash (BF) masks perception of the initial test flash (TF), at interstimulus intervals (lSI) of 0 to 25 msec. At the 20-msec lSI, when visual masking occurred, VEPs were like those of the BF at the 500-msec lSI, or when presented alone. A similar result obtained by Donchin and Lindsley (1965) led to the interpretation that the interference of TF by BF takes place at or preceding the point at which VEPs are recorded (occipital cortex). They expressed the opinion that the same processes which are involved in perceptual blanking seem to be involved in the blocking of the VEP. It wi...

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