Cognitive P300

General

The P300 (P3) wave is an event related potential (ERP) elicited by infrequent, task-relevant stimuli. It is considered to be an endogenous potential as its occurrence links not to the physical attributes of a stimuli but to a person's reaction to them. It is usually elicited using the oddball paradigm in which low-probability targets are mixed with high-probability ones.

When recorded by electroencephalography (EEG), it's as a positive deflection in voltage with a latency of roughly 300 to 600 ms. The signal is typically measured most strongly by the electrodes covering the parietal lobe though it is generated by various parts of the brain including the hippocampus.

The presence, magnitude, topography and time of this signal are often used as metrics of cognitive function in decision making processes. While the neural substrates of this ERP still remain hazy, the reproducibility of this signal makes it a common choice for psychological tests in both the clinic and laboratory.