The Frontal Cortex

fMRI Biases the Brain

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.


  1. #1 PhysioProf
    June 7, 2008

    I am a “working neuroscientist”, and I am biased against fMRI studies. In the long run, I think it will turn out to be about as useful at understanding how the brain works as phrenology. This is, of course, just my biased view.

  2. #2 Etha Williams
    June 7, 2008

    I’m not quite a working neuroscientist, but I am a student of neuroscience, and I agree with PhysioProf — I tend to be biased against studies using fMRI. While I think it can be a useful tool if the researcher understands and appreciates its limits, fMRI results in the literature seems to often lend themselves to over-simplification and unwarranted broad generalizations (eg, this part of the brain does this).

  3. #3 milo
    June 8, 2008

    fMRI, like all experimental methods, has both strengths and weaknesses in terms of its ability to address hypotheses and advance our knowledge of the workings of the human brain. To dismiss fMRI out of hand, as PhysioProf seems to be doing, seems pretty unscientific for a “working neuroscientist”.

  4. #4 PhysioProf
    June 8, 2008

    To dismiss fMRI out of hand, as PhysioProf seems to be doing, seems pretty unscientific for a “working neuroscientist”.

    Of course it’s unscientific. I explicitly said it was a bias. That means it is unscientific: an intuitive gut instinct.

  5. #5 Byron Bernal
    June 9, 2008

    fMRI is a great tool being abused by basic-science research. fMRI is currently utilized in neurosurgery in many Hospitals to help avoid resection of critical brain areas abnormaly localized.
    But, there are too many studies describing the obvious: that fMRI shows that any emotion, felling, intention, and plan comes from the brain. And many other finding activations and localization for “functions” that remind the old classificaton of phrenology. That is boggus science.

  6. #6 Kevin H
    June 9, 2008

    I’m a grad student in fMRI and I’d say that the pictures on a whole are very necessary. They allow someone who knows the field pretty well to get a pretty good understanding of what’s going on at a glance. Pictures being worth a thousand words and all.

    I’d also be surprised if this effect didn’t generalize to all forms of visual interest. I don’t think there’s anything special about fMRI pictures vs say a colored graph, other than the fact that the fMRI picture is more visual complex and interesting, grabbing more attention. We are talking about degrees of effect here, not some brain-picture-specific response.

    Comparing fMRI to phrenology means one has either very little understanding about the flaws of phrenology, or very little understanding about what fMRI is or how the brain works, or both.

  7. #7 Kevin H
    June 9, 2008

    ah, well looks like my intuition about colored graphs is off the mark now that’s I’ve actually read the paper. Still seems to me that attention must be a big factor, and that trying to limit this field of interest to fMRI is a bit silly.

    Other hypotheses that I think should follow from this work: that cellular neuroscience and animal behavior/ecology would have similar effects. For cellular neuroscience, showing (or just describing) a picture depicting co-labeling of a receptor, or other protein would probably effect the the perceived credibility of the findings. And for animal sciences, I bet including a picture of the animal would boots it’s perceived scientific gravitas.