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.
The Science: A ‘Left-Brained’ Indictment of a ‘Right-Brained’ Idea
The appeal of the theory is obvious. After all, people do seem to distinguish themselves in some clear ways: poetic or political, creative or rational, passionate or detailed. We want to believe these differences come from a very basic source, and in these times of cognitive research, the brain now stands in as the cause of things that, in earlier times, we might have attributed to the soul. But research continues to send the message that “it is more complicated than that.” Jeremy Dean’s Psyblog, for example, notes that the evidence for hemisphere-dominance in individuals was never strong to begin with. Only now an fMRI study (Nielsen et al., 2013) has driven a stake through the heart of the theory. Looking for patterns in the brain scans of more than 1,000 individuals, the study failed to find observable support for the idea that different people think with a greater ‘dominance’ of one hemisphere of the brain or the other. “We just don’t see patterns where the whole left-brain network is more connected or the whole right-brain network is more connected in some people.” Psyblog quotes lead author Jared Nielsen, “It may be that personality types have nothing to do with one hemisphere being more active, stronger, or more connected.”
National Public Radio‘s Cosmos & Culture blog also includes an on-point discussion of the research, based on an interview with cognitive neuroscientist Kara Federmeier. She notes that it is true that different brain functions are lateralized in the sense of being associated more with one hemisphere than the other, and also true that the hemispheres operate in an independent fashion at times. “However,” Dr. Federmeier notes, “it seems safe to say that for the most part we all use both sides of our brains almost all the time.”
Of course, it is still the case that some people prefer creative and holistic thought while others lead with logic and analysis. The correction that this science provides is the reminder that these are behavioral preferences, not hard-wired cognitive differences. That distinction should encourage us to view those traits realistically as ones that vary in response to circumstance and message.
The Implications for Juror Analysis
The chief takeaway for jury selection and analysis is that one should be skeptical of all efforts to put people into discrete boxes, including but not limited to the right-/left-brain dominance box. While some jurors will have adopted the behavior of leaning toward the emotive and others toward the rational, nearly all jurors have the potential for either orientation to come to the fore in different situations.
Instead of basing your selection and your adaptation on those broad categories, base it on the specific experiences and attitudes jurors or potential jurors bring to the courtroom. That means finding out as much as possible — through oral voir dire and questionnaires, where allowed — to identify the specific and not the general. And it also means thinking about both the emotional and the logical, the holistic and the analytic, in persuading your fact finders.
The Implications for Understanding Scientific Stickiness
Even with conflicting evidence, it seems likely that decades from now, we’ll still be talking about left- and right-brained people. Why? Because it is useful. As Jeremy Dean notes in Psyblog, “Despite having no solid basis in science, the expressions ‘left-brained’ and ‘right-brained’ will probably survive because it’s an easy way to talk about two aspects of personality.” I’ve noted the same about the Reptile perspective currently in vogue. Tell plaintiffs’ attorneys that science hasn’t and doesn’t support the idea of a reptile brain controlling the cerebrum, and you’ll probably be met with a great yawn of indifference. They stick with it because it is useful.
That presents a fundamental lesson to those providing scientific testimony. No, the lesson is not to stake your position on dubious or unsupported information. Instead, it is to think about what, other than validity, makes an idea stick. In the case of both Reptile and the left-brain/right-brain motif, two things stand out:
- One, the idea is simple enough in each case to be explained in a few sentences.
- Two, the idea seems to comport with our views of how people are, and how the world works.
That second feature corresponds to what the narrative theorist Walter Fisher called narrative fidelity, or the tendency for a story to be seen as more truthful when it jibes with the rest of our worldview. When new information carries that narrative fidelity, we are more likely to see it as useful. Even as it over-generalizes and makes the circumstantial seem intrinsic, the notion of left- and right-brained people is still useful because it gives us a vocabulary and a guide for what we should notice.
The implication for scientific testimony is this: Don’t just tell us why it is valid; tell us why it is useful as well.
______
Other Posts on the Brain and Persuasion:
- Speak to the Brain’s Politics
- Respond to the Reptile
- Learn to Read Jurors’ Minds: Brain Research in the Courtroom
______
Nielsen, J. A., Zielinski, B. A., Ferguson, M. A., Lainhart, J. E., & Anderson, J. S. (2013). An evaluation of the left-brain vs. right-brain hypothesis with resting state functional connectivity magnetic resonance imaging. PloS one, 8(8), e71275.
Image Credit: jvleis, Flickr Creative Commons