Tuesday, 11 September 2012

Do images colour perceptions?

With the increasing use of functional Magnetic Resonance Imaging (fMRI), the activities of a human brain at work are now routinely depicted in three-dimensional colour images. These attractive pictures of the brain are near mandatory appendages to news stories on neuroscience in the popular media and have been shown to have a persuasive effect on readers.

In an article in Cognition a few years ago, David McGabe and Alan Castel had famously shown how brain images had a hugely persuasive influence on public perceptions of stories on neuroscience. These images affected people’s judgements of scientific reasoning because they provided a tangible physical representation of brain activity.

One of the reasons of this appeal of brain images is, as John Grohol says, quite simply because “the pretty, compelling pictures of fMRI” add a colourful layer to otherwise boring psychological research – they “seem to illustrate a direct, causative relationship … even if one doesn’t exist.” This is, of course, a major challenge and, as Grohol points out, fMRI images are not always an accurate reflection of a brain’s activity and does not capture “the complexity of human behaviour.”

So yes, fMRI brain images have a persuasive influence on readers of popular science stories. But do these images have a greater persuasive effect than other kinds of images on how readers perceive a story?

Not really, going by a new study by David Gruber of the City University of Hong Kong and Jacob Dickerson of Georgetown College, USA. In an article forthcoming in the Public Understanding of Science, the two researchers report on a study in which they monitored the effect on participants of a variety of images attached to news articles on neuroscience. The images shown to the participants included fMRI images, artistic drawings and still images from science fiction films. “There is no significant difference between readers’ evaluations of an article regardless of the associated image,” the researchers say.

What this means is that each image may be persuasive in its own right. But there’s no way to predict if one kind of image is more persuasive than the other at a general level. This then is a significant extension of the McCabe & Castel study.

As Gruber and Dickerson point out, research would need to explore how images interact with a specific text and the specific context of a particular reader to affect understanding of a news story on neuroscience.

In another study focused more broadly on the impact of pictures accompanying true or false claims, Eryn Newman, a PhD student from Victoria University of Wellington, New Zealand, with researchers from the University of Victoria in British Columbia, Canada, found empirical evidence for the notion of “truthiness”— popularised by US comedian and satirist Stephen Colbert. Colbert defines truthiness as “the truth that you feel in your gut regardless of what the facts support.” The research, published in Psychonomic Bulletin and Review, found that people are more likely to believe a claim, even if it is untrue, if it is accompanied by decorative pictures:
In a series of four experiments in both New Zealand and Canada, Newman and colleagues showed people a series of claims such as, “The liquid metal inside a thermometer is magnesium” and asked them to agree or disagree that each claim was true. In some cases, the claim appeared with a decorative photograph that didn’t reveal if the claim was actually true—such as a thermometer. Other claims appeared alone. When a decorative photograph appeared with the claim, people were more likely to agree that the claim was true, regardless of whether it was actually true.

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