We all have memories that we would like to get rid of. A new study has shown that people are able to suppress memories of their not-so-beautiful deeds, as a result of which their brain activity becomes identical to the brain of an innocent person.
“By simulating theft in the laboratory, we tried to find out how successful people are in suppressing memories of the “crime” and avoiding exposure. We have found that people can effectively suppress their memories, reducing their influence on their behavior,” says Xiaoqing Hu, the lead author of the work, from the University of Texas at Austin (USA).
The experiment involved 78 students who were divided into three groups. Participants from two groups were “guilty” and given the task of finding and stealing an object from the mailbox of one of the teachers. The object was a ring, but the word “ring” was not mentioned in the task, so that at the time of testing, the memories associated with it appeared as a result of the actual “crime”, and not when the task was issued. The third group was “innocent”, the students were asked to go to the same place where the object of the “crime” was and simply write their initials on the bulletin board.
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One group of “guilty” students was given the task of suppressing memories of stealing the ring during an upcoming cover-up test (CSI). The second and third groups were not given any orders. The TSI test is based on the analysis of brain waves, it can be used to determine whether a person has information that indicates his participation in a crime or not. During the study, subjects were given a crime-related word (ring) or one of six other words (bracelet, necklace, watch, cufflinks, locket, purse). At the same time, an electroencephalogram was taken from them. Researchers were especially interested in the so-called P300 wave associated with conscious memories.
The students also took a hidden association test: they had to indicate whether certain statements were true or false. It is believed that the response time indicates the strength of a certain association – the faster the subject answers, the stronger it is, even if he tries to deny it.
In the “guilty” P300s, the reaction was much stronger when they were reminded of the object of the “crime” rather than called neutral objects – but only if they were not given the task of suppressing memories. Those who received such a task did not differ in P300 activity – just like in the “innocent” group. In the hidden association test, the “innocent” and “suppressive” groups also showed similar results.
These results suggest that the suppression of memories affects brain activity and reduces the impact of these memories on human behavior. The scientists now plan to find out if a similar effect extends to other memories. “We all once offended someone or treated someone unfairly and now we feel guilt and shame. Can we suppress these memories and what will be the consequences?” asks Xiaoqing Hu.
Подробнее см. X. Hu et al. «Suppressing unwanted autobiographical memories reduces their automatic influences: evidence from electrophysiology and an implicit autobiographical memory test», Psychological Science, May 2015.