A recent study about brain activity, out of Northwestern University, may prove promising to criminal investigators. There has been a breakthrough in scientists ability to read the brain’s activities when it comes to recalling what we have casually seen as we go about our day.
The findings were published in Psychological Science. The biggest thing the researcher’s found is a brain wave known as P300 that functions as a marker that can identify people, places, objects, and other minor details that someone sees every day.
EEG readings of brain activity show the P300 brain wave is larger when a person recognizes something they have recently seen. To map the P300 brain waves, researchers use a test called CIT – Concealed Information Test – to determine if a person can recognize information that may be related to a crime.
Most P300 studies have been done in lab settings, which is too removed from the real world to learn what a person might be exposed to in the course of a day. John B. Meixner, the lead researcher in this study, says this new study is more reliable because actual people, going about their normal lives, were used.
John Meixner and his co-author J. Peter Rosenfeld wanted to achieve more realistic results from the CIT, so they outfitted 24 college students with small cameras clipped to their clothing. Each participant wore their camera for four hours as they each went about their normal, everyday activities.
Researchers took the recordings from half the students and chose specific identifiable “probes” for each person. Then they took a bunch of corresponding items that these people had not seen and deemed these as “irrelevant”. For example: if someone went to a certain gas station that day, the researchers might include a few other gas stations as irrelevant items.
In order to simulate a real criminal investigation, the other 12 students were given the same “probe” item as the first group, as well as all “irrelevant” items. This was to compare those with knowledge of “the crime” (in this case, the probe) with those who had no knowledge of this “crime”.
The next day, the students gathered in the lab and were all hooked to EEG machines. They were then shown a series of words describing items or details from the previous day. These were the probes and irrelevant items.
The study showed larger P300 waves for probe items compared to the irrelevant ones. However, this was only evident in the students who had actually seen the probes. All 12 students had large P300 responses to the probe items they had seen. No such responses were seen from the control group who saw no familiar probes.
While these finding hold great promise in the field of memory research, they may have a real-world use in the field of criminal law. Japan and Israel already use the CIT in criminal investigations.
The Unites States does not use the CIT yet, mainly because it doesn’t quite meet the criteria needed to be used in a courtroom. Meixner and Rosenfeld both hope that these new findings may change a few minds.
Further tests will be conducted, including using actual images from the student’s cameras, instead of words, as the probes. Both researchers strongly believe that recognition will be a lot stronger, and P300 brain waves a lot larger, when actual images are shown.