Contingent negative variation

The contingent negative variation (CNV) was one of the first event-related potential (ERP) components to be described. The CNV component was first described by W. Grey Walter and colleagues in an article published in Nature in 1964. The importance of this finding was that it was one of the first studies which showed that consistent patterns of the amplitude of electric responses could be obtained from the large background noise which occurs in electroencephalography (EEG) recordings and that this activity could be related to a cognitive process such as expectancy. The contingent negative variation (CNV) was one of the first event-related potential (ERP) components to be described. The CNV component was first described by W. Grey Walter and colleagues in an article published in Nature in 1964. The importance of this finding was that it was one of the first studies which showed that consistent patterns of the amplitude of electric responses could be obtained from the large background noise which occurs in electroencephalography (EEG) recordings and that this activity could be related to a cognitive process such as expectancy. Grey Walter and colleagues conducted the experiment in the chronometric paradigm. They had noticed that the electric response became attenuated, or habituated when a single stimulus is repeated. They also noticed that the amplitude of the electric response returned when a second stimulus was associated with the first stimulus. These effects were strengthened when a behavioral response was required for the second stimulus. In a chronometric paradigm, the first stimulus is called the warning stimulus and the second stimulus, often one that directs the subject to make a behavioral response, is called the imperative stimulus. The foreperiod is the time between the warning and imperative stimuli. The time between the imperative stimulus and the behavioral response is called the reaction time. The CNV, then, is seen in the foreperiod, between the warning and imperative stimulus.