EEG

n. The EEG (or electroencephalogram) is the graph of an electrical signal produced by large groups of neurons in the brain that can be picked up by scalp electrodes. Scalp EEG recordings are frequently used in psychological or neuroscience experimentation because the process is noninvasive. Participants wear an electrode cap that records the underlying voltage fluctuations in the brain with little or no discomfort to the participant.

The EEG has very high temporal resolution and is capable of detecting millisecond-level changes in electrical activity in the brain. Most important to experimental research are ERPs (event-related potentials), which are portions of the EEG that are time locked to a stimulus onset. ERP recordings consist of a series of positive and negative peaks, whose amplitude and latency are informative about cognitive processes. The peaks of an ERP are labeled by their polarity (negative [N] or positive [P]) and their typical latency in milliseconds (e.g., P300).

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