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The present experiment was designed to investigate the factors affecting the resolution of the contingent negative variation (CNV). In the first session, 11 subjects were tested in a standard CNV paradigm. These subjects were then tested in a probability learning paradigm in which a red or green feedback light informed the subjects whether their choice of response was correct or incorrect. The feedback stimuli were presented .75, I, and 1.5 sec after the imperative stimulus. The results showed that the resolution of CNV occurred immediately after the motor response in the standard CNV paradigm. In the feedback paradigm, on the other hand, the resolution of CNV occurred only after the feedback stimulus. The results suggested that the resolution of CNV is contingent upon the psychological state of completion initiated by the feedback stimulus rather than the motor response.

The present study was designed to investigate the effect of respiration upon slowly changing potential (SCP) using controlled respiratory cycles. EEG and respiration were monitored under 3 different respiration conditions, 7.5, 15, and 30 cycles per min. The results indicated that SCP amplitude decreased as a function of respiration rate. Cross-correlation analysis also showed that SCP variation is correlated with respiration phase. Considering these results, it was suggested that respiratory phase is a variable to be controlled in studies of contingent negative variation (CNV) and other slowly changing potentials.Walter, Cooper, Aldridge, McCallum, and Winter (1964) first reported the existence of the contingent negative variation (CNV) utilizing the simple reaction time paradigm, in which a warning stimulus is followed by an imperative stimulus to which the S has been instructed to respond. Since then, a number of studies concerning CNV have been reported and they were reviewed by Tecce (1972) who showed that CNV is related to the psychological factors of expectancy, conation, motivation and attention. As CNV is a slowly changing potential (SCP), a d.c. or a.c. amplifier with long time constant must be used for recording this potential. In analyzing the recordings, an increased attention should be called to the fact that recordings by this method are vulnerable to slow potential artifacts arising in the organism as evidenced by the current studies (Tecce, 1972). The most serious artifacts for CNV result from eyeball and eyelid movements, artifacts of which can be eliminated by several techniques (Hilyard, 1974). The other movements, however, might generate slow potential shift at scalp. There is a possibility that respiration modifies the activity of nervous system, since Pitts (1946) has postulated an influence of the inspiratory center over ascending brain-stem activating mechanisms. No systematic study, however, has been done on the relationship between SCP and respiration. In order to investigate this relationship in a systematic way, a controlled respiration technique was employed in this experiment. The present study was, therefore, designed to investigate the effect of respiration upon SCP in the controlled respiratory cycles. METHODSubjects. The Ss were 12 college students; all had participated in previous experiments of CNV. Three of them were discarded from analysis, because of failure to control respiration.Apparatus. The EEG for measuring SCP was recorded between vertex and right earlobe sites using Beckman bio-potential electrodes.Respiration was recorded by a San'ei thermofor Scientific Researches (#131038), Ministry of Education.2 Appreciation is expressed to Takashi Matsuda and Naomasa Nomura for their assistance in conducting this experiment.

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The purpose of the present study was to understand both the behavioral (reaction time) and physiological (contingent negative variation and visual evoked response) bases of habituation using a simple reaction time paradigm. Each of 16 adult Ss was given a total of 200 trials with a 1000 msec S1-S2 interval. The results showed that the amplitude of contingent negative variation decreased and reaction time increased over the trial blocks. The visual evoked response, on the other hand, was not changed significantly. The marked habituation effect upon the contingent negative variation was observed in the terminal period of the interstimulus interval. The contingent negative variation (CNV)is classically elicited under the experimental condition us which a warning stimulus (Si) is presented to the S, followed, after a short interval, by an imperative stimulus (Se) to which the S has been instructed to respond. Walter, Cooper, Aldridge, McCallum, and Winter (1964) first reported the existence of the CNV utilizing this model, which is a simple reaction time (RT) paradigm. The CNV has been related to the psychological variables of expectancy, conation, motivation and attention (Tecce, 1972). The evoked response has also been shown to be influenced by psychological factors such as attention directed by counting stimuli and by reaction time task (Kakigi, Miyazaki, & Mori, 1973).There have been few studies, however, investigating the relationship between CNV and evoked response under the condition that CNV and evoked response were monitored separately using the different channels of the amplifier. In most studies, on the other hand, a single channel of long time constant or DC amplifier was used to monitor both CNV and evoked response. By using this measuring method a fast electrical activity such as an evoked response could not be exactly recorded. The present study was, therefore, designed to clarify the relationship between CNV and evoked response using different channels of the amplifier. In addition, habituation of CNV and evoked response, and RT changes during the repeated trials were examined in the present study. The phenomenon of habituation has received much recent attention.