Studying the electrical activity of the brain has revealed one amazing thing: our brainwaves are individualized and unique.

Changes in brain activity under different mental states can be studied with a number of methods, and the information obtained can then be used to identify features of users. More specifically, recording of brain activity can be carried out via measurements of neuronal electrical activity, wherein a common “brainwave” or signal used is the electroencephalogram (EEG). This kind of brain signal occurs continuously and is able to give information regarding an individual’s baseline mental activity as measured over a certain length of time.

Recordings of EEGs can be obtained with relatively cheap and mobile devices in comparison with other techniques of brain imaging. Examples of these techniques include functional magnetic resonance imaging (fMRI), which measures hemoglobin concentration (oxygenated and deoxygenated) post-magnetic field exposure, positron emission tomography (PET), which involves injection of a radioactive substance to track neuron metabolism, and magneto-encephalography (MEG), which detects small magnetic fields that are induced by the brain’s innate electrical currents. more