The ERP Technique
The event-related potential (ERP) is a derivative of the more familiar electroencephalogram (EEG). The EEG is a record of the ongoing electrical activity in a brain. When brain cells called neurons are busy processing information, they emit electrical signals. We record those electrical signals – the EEG – by placing a stretchy elastic cap on your head. The cap has electrodes sewn into it, which “listen in” to the electrical activity naturally occurring in your brain much like a stethoscope “listens in” to your heart beat.
Event-related potentials (ERPs) are exactly that: electrical potentials in the brain in response to specific events. So while we record the ongoing EEG from the electrodes in the cap, we present different types of events for the brain to respond to; for example, written words or letters, spoken words, pictures, or sounds. By measuring the brain’s response to these different kinds of events, we can learn about how the brain processes different types of information.