Event-Related Potentials (ERPs) are changes in an EEG signal that are caused by the neural processing of an event or stimulus.

ERPs are not readily visible amidst the EEG output and must be extracted during a standard sequence of procedures. These effectively ‘clean-up’ EEG data, making them palatable to statistical analysis An ERP is a waveform: A typical ERP will average the output of 100 or so EEG waves that have been produced in response to an event (e.g. a light flashing on a computer screen). This averaged ERP is recorded as a waveform, consisting of a series of troughs and peaks. The size and distribution of specific peaks/troughs in the waveform can be used as markers of specific cognitive processes. Interpreting an ERP waveform: Early waveform components, N1 and P1 are responses to the visual processing of the object. Later components, such as N2 and P3 indicate conscious processing of the event. Thus, by tracking the waveform, we can see that the brain first begins process the object at around 100ms. After 300ms it has entered consciousness, and the participant can make a judgment about that object (is it round, is it yellow?). By carefully manipulating the experiment, an experimenter can make these peaks and troughs greater or smaller in response to different internal and external demands.

ERP, evoked, related, potenital, eeg, p1, n1, p3, neuroimaging