There are companies developing devices that can read your brain’s output and use it to control external devices. The technology used is similar to that used by an MRI scanner; as with an MRI scanner these technologies have the potential of providing a wealth of benefits for health care. An example application is their use to aid people with missing limbs control artificial replacement.
These devices are getting cheaper (in the $100 range). They are being used to allow people to interact with games and other software applications. The easy and cheap availability of such brain scanning devices however raises some ethical questions. As this emotiv systems presentation shows, these devices can inadvertently read your mind. seeing what are your likes and dislikes.
Such data in the hands of a commision-based salesman is scary. It is easy to imagine a website that can assembles text and pictures on the fly (based on your preferences) to get you to buy whatever is being sold. Worse still they can sell your thoughts, such that other companies know how to target you better.
That is scary.