Evoked potentials are the potentials developed in the brain as the responses to external stimuli like light, sound etc. The external stimuli are detected by the sense organs which causes changes in the electrical activity of the brain. It is also called Event related potential.
This is a technique whereby a stimulus, such as a light flash or loud click, is repeatedly applied.
The EEG signal is recorded from a particular area of the brain.
Normal EEG activity, however, masks the brains response to a single stimulus.
Repetitive stimuli have to be used and the evoked response is distinguished from the background activity by using the technique of signal averaging.