Friday, March 19, 2010

Handedness and creationism

A few weeks back, I mentioned a paper published in Laterality that linked degree of handedness with belief in creationism. Thanks to a reader, I now have a copy of that paper.

The paper is basically what I described. The authors, Niebauer et al., used a survey to assess degree of handedness and belief in creation. Handedness was assessed using the Edinburgh Handedness Inventory (EHI). EHI measures the degree of hand preference on a scale of -100 (for absolute lefthanders) to 100 (for absolute righthanders). Niebauer et al. developed a four question Likert test to assess belief in creationism:

1. The earth was created in less than seven days.
2. Adam and Eve were the first two human beings.
3. The theory of evolution is well supported.
4. Evidence such as fossils, bones, and certain rock formations support the idea that the earth is at least millions of years old.

They coded the answers so that a score of 4 was "extreme belief in creationism" and 28 was "extreme belief in evolution." (Oddly enough, I would have answered "strongly agree" to all of those, and thus would have had a score of 16.) They administered the tests to students from two different midwestern universities. Their results supported the idea that strongly handed individuals were more likely to believe in creationist ideas.

Why would handedness be related to belief in creationism? That's covered in the introduction to the paper, where Neibauer et al. describe a model of the brain in which the left hemisphere is involved in maintenance of beliefs, and the right hemisphere "detects anomalies" in the beliefs and updates them after some threshold is reached. Brains with hemispheres that interact well should theoretically update beliefs more readily than brains with hemispheres that do not interact well.

What would this have to do with belief in creationism? They cite two papers by Evans that suggest that there is a developmental sequence of beliefs. Young children believe more readily in creationism and resist evolutionary explanations, while older children are more receptive to evolutionary ideas. So if children with a strong hand preference are exposed to information about evolution, they are more likely to resist it than children with a mixed hand preference, because brains with good interhemispheric interaction are more likely to be mixed handed individuals. To put it another way, strongly handed individuals probably need more convincing to update their beliefs from creationism to evolution than mixedhanders.

Wild stuff. Especially since I'm strongly handed. Makes me want to do my own test (with a slightly modified creationism assessment) to confirm these results.

In the meantime, though, I can see a useful application. After I read the paper, I asked some of my students whether they were strongly handed or mixed handed. They were strongly handed, so I was relieved. In the future, I could imagine using the EHI to weed out heretics before they become a problem. Maybe we could even make strong handedness a requirement to serve on the BSG Executive Council. Sure beats seeing if they weigh the same as a duck.



Niebauer et al. 2004. Interhemispheric interaction and beliefs on our origin: degree of handedness predicts beliefs in creationism versus evolution. Laterality 9(4):433-447.

Evans. 2000. The emergence of beliefs about the origins of species in school-age children. Merrill-Palmer Quarterly 46:19-52.

Evans. 2001. Cognitive and contextual factors in the emergence of diverse belief systems: creation versus evolution. Cognitive Psychology 42:217-266.