Wednesday, 19 June 2013
Jurgen Beckmann and his colleagues tested their intervention across three studies. In the first, 30 semi-professional footballers aimed penalty kicks at holes in a wall. They did this in a low-pressure situation then competitively in front of a crowd. The fist squeezing was described to participants as a way to boost concentration. Kickers who squeezed a soft ball in their right fist (activating the left hemisphere) for thirty seconds prior to the high-pressure situation choked - their performance dipped compared with the no pressure situation. By contrast, the competitors who squeezed their left fist showed no evidence of choking.
It was a similar story with 20 Taekwondo practitioners who performed kick combinations in a relaxed context and then again in a filmed high-pressure situation. Those fighters who squeezed a ball with their right fist prior to the high-pressure challenge showed evidence of choking. By contrast, those who squeezed a ball with their left fist actually showed improved performance.
The last study involved badminton players performing serves. This time there were three stages - relaxed context, high pressure, and high pressure plus fist tightening. All players showed evidence of choking in the first high pressure situation, but then players who squeezed their left fist prior to the second high-pressure challenge showed a return to normal performance levels while those who squeezed their right fist continued to choke.
Beckmann and his colleagues said their "hemisphere specific priming" intervention has practical applications for athletes. "Squeezing the left hand before performing a task under pressure may become a useful part of pre-performance routines in addition to imagination, deep breathing, or cue words."
These results are certainly intriguing but it seems amazing that such a simple task could have such profound effects (in statistical terms, the effect sizes were large). Scrutinising the methodology, the most serious problem seems to be a lack of blinding. It sounds from the researchers' descriptions as though the person instructing participants knew the purpose and rationale of the study, so it's possible their expectations about left-fist squeezing may have influenced the performers (a study last year showed how important these effects can be). It's also a shame there wasn't a no-squeeze control group.
There must also be question marks over the theory underlying this study. Beckmann's group said there is "a large body of research that shows enhanced right-hemisphere activity facilitates skilled performance." But I looked up a couple of references they cited - including EEG studies with archers and marksmen - and these showed correlations between hemispheric activity and performance, not causal effects. It's also important to remember this study didn't even measure brain activity, so the researchers are asking us to take quite a leap of faith in believing their explanation of the results. I think they realise this. "The exact mechanism underlying the effect of hemisphere-specific priming is still unknown," they wrote.
Beckmann, J., Gröpel, P., and Ehrlenspiel, F. (2013). Preventing Motor Skill Failure Through Hemisphere-Specific Priming: Cases From Choking Under Pressure. Journal of Experimental Psychology: General DOI: 10.1037/a0029852
A study published in April that linked fist squeezing with memory performance came in for some serious peer criticism.
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
Image credit: zirac