Is the Contingent Negative Variation Contingent on a Motor Response?
Ten subjects participated in an experiment in which each was presented with series of paired stimuli separated by 1000 msec. The first stimulus was a click. The second stimulus was either of two visual patterns, concentric circles or a star figure. Figure selection on each trial was determined by a random procedure.
There were four experimental conditions: 1) Subjects pressed a switch following the presentation of either figure. 2) Subjects pressed a switch following the presentation of the star only. 3) Subjects guessed prior to the clicks, which figure would appear as S2; no overt motor response was required. 4) Subjects had to add 7 to a cumulative sum following a star, and subtract 7 following the circles; no overt motor response was required.
Using data obtained from a vertex to linked ear derivation we conclude that the CNV is not contingent on a motor response to S2.
The electrical potentials recorded following S2, and in particular the positive-going “resolution” of the CNV seemed to vary systematically with the experimental conditions. An application of Tucker's three-mode factor analysis to this CNV is reported.