Thursday, 11 May 2006

Did you see what just happened?

Say someone’s mugged outside the office window – you know what happens next, everyone starts talking about it. The problem for police investigators is that the witnesses start contaminating each other’s memories. But do you think a witness’s memory would be most prone to distortion following a big group chat about the event, or following a one-on-one conversation?

Andrea Dalton and Meredyth Daneman have found our memories are most susceptible to misinformation following a one-on-one conversation, and whereas previous research has focused on peripheral information that’s not that relevant, Dalton and Daneman have shown how easily people’s memories can be distorted for information central to what just happened.

In their study, 89 students watched a five-minute clip from the film Inner Space. They then discussed the clip, either alone with one other student who was actually an accomplice of the researchers, or in a four to six-person group that included the accomplice. In both cases the accomplice said some true things about the clip but also mentioned some deliberately inaccurate things – these were either central to what happened (e.g. that the main character had avoided colliding with a car, when in fact he had hit it), or were peripheral (e.g. he got the name of the shopping mall that was featured wrong).

Afterwards the participants read 16 statements about the clip, including some of the false statements made by the researchers’ accomplice. Crucially, participants who’d discussed the clip one-on-one with the accomplice said his false statements were true 68 per cent of time whereas participants who’d had a group discussion accepted his statements 49 per cent of the time.

This sometimes included the misremembering of central events – participants accepted false statements about central events made by the accomplice 35 per cent of time (versus 82 per cent for peripheral events, and 10 per cent for false statements about central events not mentioned by the accomplice).

“A thorough investigation of the extent to which eyewitnesses’ memories can be altered may contribute to greater acknowledgements within the justice system that absolute reliance on even the most convincing of testimonials may be dangerous”, the researchers said.

Dalton, A.L. & Daneman, M. (2006). Social suggestibility to central and peripheral misinformation. Memory, 14, 486-501.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

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