Left Hand Activity Increases Associative Performance

I have always been a skeptic of the claim that creativity is located in the right brain. This claim originated in the early 1970s, after neuroscientist Roger Sperry discovered that surgically severing the connection between the two brain hemispheres could cure extreme cases of epilepsy. The procedure, called a commisurotomy, indeed cured the epilepsy. The problem was that the two hemispheres could no longer communicate. In most everyday life situations, these patients behaved normally and no one could tell they had, essentially, two distinct brains in their skull. But Sperry came up with a series of clever experiments such that information would be presented only to one hemisphere (to the right or left visual field) and the patient asked to respond with only one hemisphere (just the right or the left hand). The results were complex but intriguing.

The popular media grabbed onto highly simplified interpretations of these findings; books like Robert Ornstein’s 1972 The Psychology of Consciousness and Betty Edwards’ 1979 Drawing on the Right Side of the Brain popularized the notion that creativity was located in the right brain. The only problem was that this was completely untrue, a radical misrepresentation of Sperry’s findings. Through the decades since, pretty much all neuroscientists agreed that creativity involved the entire brain, the left and right hemisphere working together, and the serious research focused on the specific roles of each hemisphere in the creative process.

In the last ten years or so, brain imaging studies using fMRI have resulted in a new wave of studies of what is known as “hemispheric specialization” or “localization.” The findings are mixed*, with some studies showing increased LH (left hemisphere) activation and some showing increased RH–although the majority of the studies come down on the side of RH. Keep in mind that in all of these studies, “increase activation” means approximately 3 percent more than baseline, and even less of a difference between the hemispheres…reinforcing the general truth that creativity involves the entire brain in concert. And “creativity” means different things, depending on the test being used, but almost never means real-world creative performance.

The latest study on this topic was published just last year**. The researchers put 40 people into three groups. Group 1 was told to squeeze a ball for 45 seconds with their left hand (thus using the RH); Group 2 was told to squeeze with the right hand (thus using the LH); and Group 3 didn’t squeeze a ball at all. Then, everyone was given a type of creativity test called the Remote Associates Test (RAT) which presents you with three words, and asks you to identify a fourth word that’s related to all three of them. They were given 25 of these triplets and 15 minutes to solve them.

The findings were pretty amazing:

Right hand squeeze: solved an average of about 8 of the 25

No squeeze: solved an average of about 10

Left hand squeeze: solved an average of about 12

Something as simple as increased muscular activity on the left side of your body, stimulating RH activity, can have the effect of enhancing associative performance! And activating the OTHER side of your body and thus the LH actually inhibits performance.

I’ll close with a caveat: Of course, creativity is not the same thing as doing well on the remote associates test. The bulk of the research tells us that creativity is not lateralized in either hemisphere. But associative ability is one cognitive ability that is implicated in real-world creative performance.

*Hemispheric specialization and creative thinking: A meta-analytic review of lateralization of creativity Brain & Cognition, Volume 72, issue 3 Pages 442-448. Konstantin M. Mihov, Markus Denzler, Jens Förster

**Abraham Goldstein, Ketty Revivo, Michal Kreitler, and Nili Metuki. Unilateral muscle contractions enhance creative thinkingPsychon Bull Rev 2010 17:895-899; doi:10.3758/PBR.17.6.895

3 thoughts on “Left Hand Activity Increases Associative Performance

  1. Keith

    Recently I have come across a variety of articles and speeches on youtube referring to studies challenging the previous, and in some cased still being claimed, brain localization theories.

    There were studies that challenged Sperry, Bogen, Gazaniga studies in the 70s and 80s that I found when I was writing my dissertation.

    Also while working on my own studies of sources of creativity in the late 70s and 80s I saw that the statement that CREATIVITY is a right brain function (first of all it it the result of some to many different brain functions) was false and have been disputed that for over 30 years.

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