By Dr. Ken Broda-Bahm:
Okay, let's line up: Emotional people on the right, logical people on the left. Where would you line up? Too simple? Turns out it is. The idea of classing people in broad categories like emotional/logical, creative/analytic, or "left-brained"/"right-brained" is a staple of folk psychology commonly applied to the task of audience analysis. The brain difference in particular is a common enough reference point that it no longer may be necessary to point out the association between the emotional, intuitive and creative right-brained thinker and the logical, mathematical, and analytic left-brained thinker. The terms have naturally bled into juror analysis as well, with some commentators suggesting that speaking to the left- or right-brained jurors can be an important step in courtroom persuasion. It turns out, however, that we simply aren't either left- or right-brained. The theory was never very well-supported, and now a new study has used fMRI imaging to show that it is flat out wrong.
The case of the left- and right-brain belief provides another reason to be suspicious of science commentaries that purport to provide simple and comprehensive classifications for people. It is also another good example of science that is created and persists more because it is seen as useful rather than because it is valid. That observation about what sticks in science carries a lesson for scientific expert witnesses as well. This post will look how at we know the popular belief is wrong, and will consider implications for both audience analysis and how we understand science.