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What is electroencephalography (EEG) and how does it work?

When we are awake, when we are asleep, and especially when we are making a decision or performing an action: our brain’s activity is non-stop, demanding and involves many different areas in interpreting the stimuli to which we are exposed.


This activity is observable and measurable thanks to electroencephalography, also known as EEG, a measuring instrument used in neuromarketing.

How does electroencephalography work?

Electroencephalography measures the electrical impulses that enable neurons to communicate and exchange information. This is achieved by placing a series of electrodes on the skull and using them to observe the impact of input on the brain at an unconscious level, recording how much and in what way the neural networks in the different parts of the brain are activated in response to that input.

The brain’s electrical signal is reproduced on a graph, the electroencephalogram: a computer connected to the instrument is then delegated to analyse the results.

EEG: different types of brain waves

Thanks to EEG, it is possible to observe brain activity in association with the frequency of the brainwaves produced by our brain, which differ according to the different levels of information processing. This makes them useful for informing us about the different processes and mental states we experience while performing an activity.

Brain waves are divided into:

  • ALFA waves: predominant when awake and relaxed, they are usually recorded when the person observed has their eyes closed;
  • BETA waves: these waves usually indicate a state of brain activation or alertness;
  • GAMMA waves: observed during more elaborate cognitive activities and mnestic consolidation;
  • THETA waves: evident during states of fluctuation, such as dozing or meditation, or during states of emotional tension;
  • DELTA waves: the waves that predominate during deep sleep.

EEG and other tools

To carry out a more complete and effective neurometric analysis, EEG is usually combined with other neuromarketing tools, for better observation of people’s unconscious behaviour. Electroencephalography is often used in conjunction with eye-tracking and biofeedback.

What makes EEG so advantageous and effective is its ability to provide time-accurate information on the person’s brain signal observed during a test. Results on brain activation in relation to a stimulus can be obtained within a range of milliseconds.

How does neuromarketing use EEG?

EEG can be very useful for advertising and marketing, helping to identify the moment-by-moment response of potential customers to a new product, a billboard, a commercial, or even during an entire in-store experience. Electrodes are applied to the candidate using a portable helmet.


Let’s use a practical example: a study by Rome’s La Sapienza University tried to establish whether there was a difference in the brain activation of different people when they watched a commercial, and whether the commercial had an impact and was memorable at an unconscious level. The results showed that those who remembered the commercial some time after watching it had a different type of brain activation than those who had forgotten it.

While watching the test video, participants experienced increased activation in the frontal areas of the left hemisphere, resulting in increased GAMMA and THETA waves. As neuroscience explains, the left hemisphere would be particularly active during the encoding of material to be remembered, while the right hemisphere would be active during the recall of memories.