EEG stands for electroencephalogram. It is a procedure used to measure the electrical activity produced by the brain. Voltage fluctuations produced by large numbers of neurons firing in synchrony are conducted through brain tissue and the skull. This activity can then be recorded by electrodes placed at various locations on the scalp. Unfortunately, EEG is not sensitive to all of the activity occuring within our brains but one major advantage is its excellent temporal resolution. What this means is that neural activity picked up by EEG is recorded in real time and any delays are in the order of milliseconds.

In research, EEG is often recorded while participants complete some sort of cognitive task. Analyses can then be performed to compare the activity produced by different conditions. So, for example we might look at what happens when someone recognises a previously presented stimuli and compare this to what happens when someone see a new stimuli that has not been previously presented.

EEG is a very safe and non invasive procedure. It involves wearing an elasticated cap with small holes in it. Each hole is filled with a small amount of conductive gel and then electrodes are inserted into each of the holes.