Using lightweight electroencephalography (EEG) to exploit the fringe P3 response

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For a long time, police sketch artists have been used to build a profile of a suspect. They have utilized witness statements and victim reports, however, this method for identifying suspects can be unreliable since the witnesses can hold information back or not be truthful in their statements. Strides have been made in recent years with the more widespread use of the electronic facial identification technique (E-FIT) and even more recently the introduction of artificial intelligence to aid the creation of these E-FIT profiles. These methods still suffer from witness bias and countermeasure techniques since they require a testimony from the witness to create. Sometimes these E-FITs get attention from the news and social media for their comical appearance which can adversely affect the investigation [6-8]. Despite this, E-FITs are used by over 30 countries around the world and have success rates between 40-55% which raises the question of how these images can be made tamper-proof to enable better accuracy and more rapid image generation [5].Current research into improving the precision of the E-FITs by VisionMetric Ltd uses rapid serial visual presentation (RSVP) to measure the brains responses to images that bear resemblance to the suspect. RSVP and other electroencephalography (EEG) based concealed information tests, in combination with the Fringe-P3 method, have proven to be a promising method for forensic applications. For example, the Frings-P3 method has been used to detect subject's email addresses correctly in a stream of addresses thus linking an individual's online identity to themselves [1]. It does this by showing the subject a series of images or similar stimuli on a screen fast enough that the subject does not get enough time to consciously think about the information they have been shown, but the brain does recognise familiarity. Researchers were able to detect a P3 response when the subject was shown a familiar item, in this way you can bypass countermeasure techniques that a subject may try and deploy. In 2014, researchers were able to use this RSVP method to show that you can successfully bypass countermeasure techniques [3]. In this example, the researchers showed the subjects names on the screen and some of the subjects were told techniques to try and dampen the response when a familiar sample was shown, and some subjects were told to try and elevate the response measured to the control stimulus. This research demonstrates that by using this method you are able to bypass countermeasure techniques employed to trick systems like lie detectors which has been a problem for law enforcement agencies for decades.Although these methods show promise, the major drawback is the EEG equipment needed in order to carry out the tests. In a research environment, the traditional equipment is suitable however there is a long preparation time, requires training on a per subject basis and the equipment is bulky and uncomfortable for the wearer, often requiring many electrodes to be placed on the scalp of the subject, therefore not easily deployable in a real-world scenario. To address this issue, researchers have developed a new EEG called SKINTRONICS. This device, which is wireless, lightweight and suffers from a lot less electromagnetic interference has been shown to have the same if not better accuracy than traditional benchtop EEG systems [4]. Although the system has proven to work, it has never been applied to detecting P3 waves. If we could develop a method to accurately combine these methods and prove you can generate increasingly more accurate images based on the brains P3 response it would be an valuable piece of research and would aid law enforcement agencys around the globe.