The true P3 is hard to see: some comments on Kok's (1986) paper on degraded stimuli.
Kok (1986) investigated why P3 amplitudes are reduced when stimuli are degraded. He proposed that a positive moment-related component might overlap P3 after intact stimuli and a negative one after degraded stimuli ("MRP overlap" hypothesis). Discussing his findings, it is suggested that MRP overlap can only account for the result if another overlap hypothesis ("nogo overlap") is added. But even this combined hypothesis cannot explain reducing effects of degradation found in other paradigms. While other overlap hypotheses have been proposed in the literature, the most parsimonious hypothesis is to assume that P3 itself gets smaller after degraded stimuli.
Verleger
R
R
Dept. of Neurology, Medical University, Lübeck, F.R.G.
D001143:Arousal / Q000502:physiology*; D001288:Attention / Q000502:physiology*; D002540:Cerebral Cortex / Q000502:physiology; D003265:Contingent Negative Variation; D004569:Electroencephalography; D005074:Evoked Potentials, Visual; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology