Brain fingerprinting is a technology designed to detect concealed information stored in the brain. The technique consists of measuring an electrical brain wave responses to specific stimuli such as words, phrases or pictures presented on a computer screen. But, how can we use this mind-reading tech? It sounds absurd, but brain fingerprinting can help us to flush out criminals.
During a brain fingerprinting test, a computer program can analyze the data collected to determine if there are crime-relevant information stored in the brain of the suspect. Indeed, if a subject is shown something which poses some significance, their brain waves will react in a particular way, allowing us to know that the suspect recognizes the item.
The G.B. Grinder case
In 1999, a woodcutter named James Grinder had confessed to murdering Julie Helton, a woman who had died 15 years prior. A short time later, the man retracted his statements, contradicting himself time and time again. With evidence being decades old, the police were struggling to devise a case strong enough to convict Grinder and so the Sheriff decided to call in Lawrence Farwell, a doctor who had been working on something revolutionary. Farwell had discovered a new way to determinate the guilt or innocence of a suspect by measuring their brain activity. According to Farwell, this method was “more advanced and accurate than a lie detector”.
The first application of brain fingerprinting
During the test led by Farwell, Grinder viewed short phrases flashed on a computer screen, some of which were probe stimuli containing specific details of the crime that would be known only to the perpetrator. These included the murder weapon, the method whit which the victim was killed, the injuries inflicted on the victim, what the perpetrators used to bind the victim’s hands, the place where the body was left, items that the perpetrators left near the crime scene and items that were taken from the victim during the crime.
Computer analysis of the brain fingerprinting test found, with a statistical confidence level of 99.9%, that the specific details of the crime were recorded in Grinder’s brain as “information present”. That means that the details of Julie Helton’s murder were recorded in the suspect’s brain.
Following the test results, Grinder faced a probable death sentence. So, he pled guilty to the rape and murder of Julie Helton in exchange for a life sentence without parole and also confessed to the murders of three other young women.
This was the first real-world law enforcement use of brain fingerprinting. Afterward, the method has been successfully applied in real-world cases and ruled admissible as scientific evidence in court.
How does it work?
Brain Fingerprinting use the P300 component of the event-related brain potential (ERP). The name P300 refers to the fact that the response is electrically positive (P) and has a latency of at least 300 ms (300). The potential occurs when a subject recognizes a stimulus as significant in the context in which it is presented.
In the early P300 research, the responses were evoked by very simple stimuli such as clicks or tones. Then, scientists began to use more complex stimuli. With a more rich and complex stimulus, the response is delayed, because the subject takes longer to discern what the stimulus is and evaluate its significance.
The electroencephalograph (EEG) signals used for brain fingerprinting are recorded non-invasively from the scalp.
The discovery of P300-MERMER
Later, Farwell discovered that the P300 can be considered to be part of a larger response he called P300-MERMER, a memory and encoding related multifaceted electroencephalographic response. Brain fingerprinting using the P300-MERMER has resulted in no false positives, no false negatives, and no indeterminates. However, it doesn’t mean that brain fingerprinting is 100% accurate, because such a statement contains an implicit prediction about the future. A technology that is “100% accurate” never makes an error, now or ever.
However, results obtained confirm that brain fingerprinting can accurately detect the presence or absence of concealed information. This means that this technology can generate useful forensic evidence in real-world applications national security and criminal justice.