Graded cue information in dichotic pitch: effects on event-related potentials.

To determine whether electroencephalogram components elicited by dichotic pitch stimuli are all-or-none threshold-like responses or graded responses that depend on the saliency of the stimuli, we recorded electroencephalograms while participants listened to dichotic pitch stimuli constructed with different signal-to-background ratios. The object-related negativity and P400 components were largest when the dichotic pitch was most salient (high signal-to-background ratio), and decreased in amplitude with decreasing signal-to-background ratio. These results are similar to those reported for mistuned harmonics, thereby providing additional evidence that the object-related negativity and P400 components observed for these disparate stimulus types reflect similar processing. They also support the notion that the object-related negativity and P400 amplitudes are dependent on the level of relevant cue-based stimulus information.