Criminal with VR glasses betrays himself with just one glance
Memory detection methods have been proven for decades, yet only the Japanese police work with them. PhD student Ine Van der Cruyssen devised a variation on the test in which suspects visit the crime scene in virtual reality (VR). “Culprits looked at the changes much earlier and longer than innocent people.”
Not everyone wanted to cooperate with UvA psychology doctoral student Ine Van der Cruyssen's research. Indeed, in her doctoral research, a collaboration between the UvA and the Hebrew University of Jerusalem, which she conducted in Israel, subjects were sent out to steal money and jewelry in the lab of fellow researchers. “Of the 40 subjects, 33 eventually completed the study,” Van der Cruyssen says. “A few refused to steal the jewelry or failed to steal it.”
The subjects were divided into two groups: the “guilty” ones were sent to the neighboring lab to steal money and jewelry; the “innocent” ones had to go read some posters on campus for form's sake. Then the whole group got back together and told the investigators that a crime had been committed and that they would be interrogated.
The test subjects were all given VR glasses with which they visited different virtual locations: one of which was the lab where the money and jewelry had been stolen. Van der Cruyssen says: “In the VR images of the lab, we had changed things. For example, a blue backpack had suddenly turned red and the large dartboard that hung prominently on the wall had disappeared.”
This is noticeable when you recognize the room, but not when you first see the room. The researchers wanted to make exactly that distinction. Van der Cruyssen: “The ‘guilty’ subjects looked much earlier and longer at the empty wall and the red backpack in the crime scene than the ‘innocent’ subjects.”
The researchers were able to measure this by looking at where the subjects looked the longest and most. “Eye movements very often happen unconsciously and very quickly. This makes them reasonably resistant to faking, should the suspect already be familiar with the test. “In this way, Van der Cruyssen was able to significantly distinguish the guilty from the innocent. “Although some ‘guilty ones’ said afterwards that they had not realized at all that anything had changed in the lab.”
Japanese police
That memory detection works has been demonstrated for decades. The best-known form of memory detection is the concealed information test. In this, suspects are shown the murder weapon, such as a knife, along with some equivalent alternatives such as a hammer or a gun. The idea is that the guilty will react differently to the murder weapon than to the alternatives, while innocent people react equally to the objects. Scientists measure this by measuring heart rate, breathing, and skin conductance - how much you sweat.
Yet for now, only Japanese police are working with memory detection. “The problem is that it requires a lab and scientifically trained personnel, personnel who are also well versed in the murder case,” Van der Cruyssen explains. In Japan, cooperation between police and science is closer, the doctoral student says.
What the test subject sees through the VR glasses. The heatmap shows where the subject’s gaze lingered longest and most. Left: innocent, Right: guilty. It is a different situation than described in the article.
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Leak problem
In addition, controls in Japan are stricter on leaking information to the media. “This is because the test measures whether the suspect has knowledge about the crime, but not how that knowledge was acquired. If you have already read in the newspaper that a knife was used, there is a risk that you will test positive.”
Van der Cruyssen's research with the VR glasses may offer a solution to that leakage problem. “We have now shown that changes in the crime scene can separate the guilty from the innocent. Should it be leaked that the crime scene was a kitchen, the police can still use the kitchen as a situation and make changes to it in VR. That way the police remain in control.”
This has now been demonstrated in a relatively small study; the follow-up study with a larger group of subjects has also been set up in the meantime. “There we also want to investigate how guilty people react to the crime scene without changes, as a control group. That would strengthen the evidence that the changes cause the eye movements, and not the fact that the subjects recognize the space.”
Ine Van der Cruyssen received her doctorate on September 29th for her dissertation “Reading the Criminal Mind: Exploring Novel Methods of Memory Detection.”
