The term event-related potential (ERP) refers to changes in the
brain's electrical activity locked in time to an externally defined
event. ERPs have been used since the early 1960s, when they were
usually referred to as ‘evoked potentials,’ to investigate
sensorimotor and cognitive function in healthy and clinical
populations.
Event-related potential (ERP) is a very small voltage brain
activity that is the direct result of a specific sensory, cognitive
or motor event. It is any stereotyped electrophysiological response
to a stimulus. The transient electric potential shifts (the ERP
components) are time-locked to the stimulus onset. Each ERP
component reflects the brain’s activity which is associated with
one or more mental operations.
Event-Related Potentials (ERPs) are measured brain responses to
particular stimuli. ERPs are measured through
electroencephalography (EEG), a non-invasive procedure which
measures electrical activity of the brain via the use of electrodes
placed on the scalp.
As the EEG reflects thousands of simultaneously ongoing brain
processes, the brain response to a single stimulus or event of
interest is not usually visible in the EEG recording of a single
trial; to see the brain response to the stimulus, the experimenter
must conduct many trials and average the results together, causing
random brain activity to be averaged out and the relevant ERP to
remain
A key advantage of ERP methods is that they provide measures of
neural activity with very high temporal resolution. The superior
temporal resolution of ERPs makes them well suited to examinations
of neural events responsible for human memory, which can
potentially be monitored by ERPs on a millisecond-by-millisecond
basis. Critical memory processes often unfold within the first
second after exposure to a stimulus, and ERPs can allow these
processes to be resolved in real time and with randomized trial
orders.
ERPs are used in psychology because they allow one to obtain
information about the intact human brain and how it processes
signals and prepares actions. Processing of irrelevant information
which does not require an overt response, processes of repressing
and forgetting, and mechanisms of erroneous responses, are only
some examples of problems about which no direct information can be
obtained via overt behavioral measures.
ERPs have been employed in memory research to identify neural
activity associated with both encoding of information into memory
and the later retrieval of stored information. Notably,
dissociations between the different ERP correlates of recognition
memory offer strong support for dual-process models of recognition.
ERP findings further point to a dissociation between the neural
correlates of successful recognition and recall.