Brain Responses

Basis of the BCI

Your brain reacts to contrast changes. This is what happens every time a button goes from white to black and from black to white. This brain responses is the basis of our BCI technique, often referred to as cVEP (code-modulated Visual Evoked Potential). The code-modulated stems from our Gold codes (minimal correlation between the flickering patterns) that are modulated such that there can only be short (1 bit) and long (max 2-bit) flickers (ie. on-off-on and on-off-off-on).

During calibration the system is trained to recognise your brain response to one flickering. With this information we can extract information of what you are looking at on the screen (which flicker pattern you are attending to).

You can find your brain response to the flickering, by navigating to the local website and clicking on the logs in the documentation section. For more info, read the configuration page .

As this system is a very quick response in response to a stimulus, timing is crucial when working with this system. Delays may therefore cause performance decreases.

Refer to this article for some general information on the BCI.

Performance

Your performance will increase slightly over time. This is due to you getting familiar with the best looking-technique and training yourself not to be distracted by other buttons.

Some people will have higher performance than other people. This is determined by the way your brain is formed. For example, sometimes the relevant visual area lays more hidden inside the brain instead of on the outside. PLEASE NOTE: It is not an indication of something wrong with your brain if the system works less than on other people.