Beware of Brain Images

Via the British Psychological Society’s excellent blog comes news of this study: MCCABE, D., CASTEL, A. (2008). "Seeing is believing: The effect of brain images on judgments of scientific reasoning," Cognition, 107(1), 343-352.

From the abstract:

Brain images are believed to have a particularly persuasive influence on the public perception of research on cognition. Three experiments are reported showing that presenting brain images with articles summarizing cognitive neuroscience research resulted in higher ratings of scientific reasoning for arguments made in those articles, as compared to articles accompanied by bar graphs, a topographical map of brain activation, or no image. These data lend support to the notion that part of the fascination, and the credibility, of brain imaging research lies in the persuasive power of the actual brain images themselves. We argue that brain images are influential because they provide a physical basis for abstract cognitive processes, appealing to people’s affinity for reductionistic explanations of cognitive phenomena.

As the BPS blog elaborates:

David McCabe and Alan Castel presented university students with 300-word news stories about fictional cognitive research findings that were based on flawed scientific reasoning. For example, one story claimed that watching TV was linked to maths ability, based on the fact that both TV viewing and maths activate the temporal lobe. Crucially, students rated these stories to be more scientifically sound when they were accompanied by a brain image, compared with when the equivalent data were presented in a bar chart, or when there was no graphical illustration at all.

This fits in with the theme of how people tend to overvalue something that is dressed up in the attire of science. 

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  • Silas

    And was this claim about bias substantiated by brain scans of the subjects? That would definitely make it more persuasive for me.

  • Fortunately, we don’t rely upon university students to judge advancements in science.

    I wonder what results they would get if they presented cognitive science professionals with articles for peer review, with brain images, with bar charts, and without graphics. Not that I’m suggesting peer review is without its biases, but I would expect it to be less influenced by the inclusion of brain images.

  • Brad Hutchings

    So who’s taking bets on how this applies to the much more relevant question of how people perceive global warming stories that intersperse pictures of drowning polar bears?

  • I believe this cognitively-convincing effect of the published visual image is an almost fully-sufficient explanation for why brain imaging has so dominated neuroscience for the past two or three decades.

    Certainly, brain imaging has not made any significant scientific contribution (other than confirming one or two things already known – and even this may well be a product of publication bias).

    Also important is that brain imaging is capital intensive; which (anti-competitively, by raising the cost of entering the market) serves to perpetuate the dominance of already-dominant scientific groups and institutions.

    In other words, brain imaging has enabled very-expensive and fourth-rate (stamp-collecting) science convincingly to spin-itself as revolutionary.

  • The thing that puzzles me about some brain-scan research (particularly in neuroeconomics, marketing, etc.), is how they get subjects to perform various activities or think about various subjects while in an MRI machine. I’ve had an MRI myself, and the machines are very claustrophobic; they can easily induce a feeling of oppression and panic. If that’s the environment in which people are shown something that they’re supposed to react to, how do we know that their brain activity is unaffected by the claustrophobic and highly artificial environment? Or am I completely misunderstanding such research — are they somehow getting high-res images of brain activity of people going about their normal activities in a natural environment?

  • Adam Safron

    Stuart Buck: Claustrophobia is usually an exclusion criterion for fMRI experiments. During experiments, participants are required to keep their heads as still as possible. Images are displayed on a flat surface using a projector, and the participants have a view of this surface through a mirror that’s placed in front of their eyes. Responses are given using button boxes and other such devices that can be used with hands without extensive physical effort. It’s true that the MRI environment might influence cognitive processing in some ways, but since this is a constant factor across the experiment, this should subtract out when you compare between experimental conditions (and different conditions are counterbalanced to ensure that habituation to the scanning environment isn’t a confounding factor). Converging results from PET imaging and TMS and the neuropsychological literature suggest the results generated aren’t unique to the fMFRI environment. It’s possible that the results don’t generalize to cognitive processes in claustrophobics, but this seems unlikely.

  • Adam Safron

    Bruce G Charlton: Brain imaging is a valuable converging line of evidence that can be used to triangulate upon cognitive processes. Behavioral experiments and neuropsychological data can often be interpreted in multiple ways, and brain imaging provides useful information for disambiguating between competing hypotheses (see the debate on implicit/explicit memory). In my own work, I’m investigating affective phenomena that were previously difficult to investigate without brain imaging.

  • Well, did McCabe-Castel randomize the brain images? If not, then why not infer, for example, that brain images may be more salient than other kinds of visual persuasion?

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