Wednesday, 25 April 2012

Psychologists create non-believed memories in the laboratory

Most of the time our autobiographical memories and beliefs match up - we remember last week's journey to a conference and believe that journey really took place. Other times, we believe an event happened - we know we travelled to that conference - but our memory for the event eludes us, perhaps because the trip was so boring or because we drank too much wine.

Recently, psychologists have begun to examine the rarer reverse scenario, in which we have what feels like a memory for an event, but we know (or believe) that the event never happened - we recall the conference journey but know we couldn't have made it. A recent survey (pdf) of over 1,500 undergrads found that nearly a quarter reported having a non-believed memory of this kind. Now Andrew Clark and his colleagues have gone further - for the first time actually provoking non-believed memories in the lab.

Twenty participants were invited to a psychology lab for what they thought was a study into mimicry. Each participant was filmed as they sat opposite and mimicked the actions of a researcher, including clapping their hands, rubbing the table, and clicking their fingers. Each time, the participant would watch passively and then mimic. Altogether 26 different actions were mimicked by each participant.

The clever bit came two days later when the participants were shown clips taken from the earlier footage. These clips showed them sitting passively, watching the researcher perform 12 different actions. In each case, the participant now had to say whether they remembered performing each action, and how strong their belief was that they'd performed each action. Crucially, two of the clips had been doctored - footage of the watching participant had been superimposed over a separate video of the researcher performing two actions that were never part of the original mimicry sessions. Because the participants had earlier mimicked all the actions that they'd witnessed, the doctored footage gave the strong impression that they must have mimicked those two new actions even though they hadn't. This set-up provided a powerful means of inducing false memories - 68 per cent of the participants' memory ratings for the fake actions suggested they "remembered" performing the actions. Their belief that they'd performed these actions was similar in strength to their memories.

Four hours later, the participants returned for a final session in which they were told about the trickery. They were then asked again to provide "memory" and "belief" ratings for the different actions. The take-home finding is that for 25 per cent of the fake actions, the participants now reported significantly stronger memory scores than belief scores - in other words, their (false) memory of having performed the fake actions persisted even though they often no longer believed they'd performed the actions.

Clark and his team said that their findings raised ethical questions about memory research: "To the extent that debriefing might not always completely 'undo' the effects of suggestive manipulation, we might question the ethics of inducing false memories in experimental participants. Is it ethical for participants to leave research labs with remnants of non-believed false memory content in the forefront of their minds?"

A question for future research on non-believed memories is whether belief is needed for the initial formation of the memories, even if that belief later falls away. "Or, alternatively," the researchers said, "can memories form completely in the absence of belief?".

Clark, A., Nash, R., Fincham, G., and Mazzoni, G. (2012). Creating Non-Believed Memories for Recent Autobiographical Events. PLoS ONE, 7 (3) DOI: 10.1371/journal.pone.0032998

Further reading: Charles Fernyhough's blog post on non-believed memories: "Remembering events that never happened."

Post written by Christian Jarrett for the BPS Research Digest.

1 comment:

  1. A well known filmed experiment, more than twenty years ago, in which a subject had fragments of a scenario planted under lab conditions and awoke to recall not only the prescribed scenario but enhanced and developed.