Dave Munger has a great post on how fMRI images bias the brain. The researchers asked 156 students at Colorado State University to evaluate three different summaries of brain research. As you can probably guess (especially if you’re familiar with this research) the students gave significantly higher ratings for “scientific reasoning” to articles accompanied by pretty pictures of brains. Anatomy is persuasive.
In a final experiment, McCabe and Castel modified a real write-up of a real brain-imaging study, which argued that brain imaging can be used as a lie detector. Students read one of two different versions of the article. One version contained criticism from a brain researcher who wondered whether the technique would work in the real world, while the other omitted the criticism. These groups were again divided into two groups, one of which saw a brain image accompanying the article, and the other who read the article without any images.
Once again, the agreement with the article’s conclusion was significantly higher when a brain image was presented, even though the same evidence was presented in textual form in the article, making the brain image redundant. Even more striking, while agreement with the conclusion was affected by the presence of the brain image, the presence or absence of substantive criticism had no effect.
I’d like to see this study repeated with working neuroscientists. Are they also suckers for fMRI images? If so, should journals modify their graphic policy? After all, there’s no reason why fMRI data needs to be represented with a saggital image of the cortex, complete with splotches of primary color. (Presumably, neuroscientists already know the location of the brain areas showing increased activation. They don’t need yet another image of a excited amygdala or OFC.) You could just as easily (and perhaps more accurately) represent fMRI data with a bar graph. But perhaps scientists intuitively sense that a graphic without anatomy wouldn’t be quite as effective.