What is Event-related potential?
An event-related potential (ERP) is a measured brain response that is directly time-locked to a specific sensory, cognitive, or motor event. ERPs are extracted from EEG recordings by averaging brain activity across many trials to isolate the signal from background noise.
How it works
ERPs consist of a series of positive and negative voltage deflections (components) that reflect different stages of information processing. Key components include the P300 (attention and memory updating), N400 (semantic processing), N170 (face recognition), and ERN (error detection). Each component has characteristic timing, scalp distribution, and sensitivity to specific experimental manipulations, making ERPs a powerful tool for dissecting the stages of cognitive processing.
Applied example
When a person reads a sentence ending with an unexpected word (‘I drink my coffee with cream and socks’), the N400 component shows a large negative deflection about 400 milliseconds after the unexpected word, reflecting the brain’s detection of semantic incongruity.
Why it matters
ERPs provide a real-time window into the brain’s sequential processing of information, revealing the hidden stages between stimulus and response.
