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Squeezing a Rubber Ball May Boost Creative Thinking

a simple way to encourage creativityPsychological research suggests a simple brain hack for temporarily boosting creativity and all it requires is a rubber ball. The technique itself is extremely simple: all you have to do is squeeze a rubber ball with your left hand as hard as you can for about a minute.

An original study on this technique by four Israeli researchers (Goldstein et al., 2010) found that subjects who squeezed a rubber ball with their left hand solved noticeably more problems on a remote associates test, a standard test of convergent thinking. This form of creative thinking, usually contrasted with divergent thinking, is most useful for “connecting the dots:” combining existing information, comparing and juggling ideas, solving problems with some specified criteria, or extracting ideas from other information. A lot of real-world innovation or typical business problem-solving depends heavily on convergent thinking.

The participants in the left hand group solved on average 50 percent more of the problems than did those in the right hand group. Interestingly, subjects who squeezed the ball with their right hand solved even fewer problems than subjects in the control group, who were not doing any hand clenching at all.

Hardball Dilemma
The original study on this technique showed that it helps with problems of convergent thinking, but a relatively recent study by JongHan Kim (2015) published in Creativity Research Journal puts an interesting twist on this brain hack: squeezing a ball may improve either convergent thinking or divergent thinking and it all depends on the ball’s hardness.

Squeezing a hard ball such as a regular lacrosse ball will boost convergent thinking. On the other hand, squeezing a soft ball such as a typical stress ball made of gel or preferably something even more malleable will boost divergent thinking. Divergent thinking, in contrast to convergent thinking, is primarily about flexibility, free-flowing unconstrained ideation, and thinking straight outside the box.

Why it Works:

1. Increased activation.

There are several explanations for why this technique works. One view, favored in the original study, is that clenching the left hand activates motor regions in the right hemisphere, and this activation in the motor cortex spreads to other regions in the right hemisphere. This tilts the overall hemispheric balance toward the right brain, which is responsible for greater creativity.

2. Decreased activation.
A competing explanation seems to get stronger experimental support from a study published in December 2015 by a group of German researchers (Cross-Villasana et al 2015). These researchers argue that hand clenching works not by increasing activation but rather by decreasing it. More precisely, activation is increased during the hand clenching, but as soon as the hand clenching stops, it leads to reduced overall activation. This reduced activation helps most likely because it prevents competition and interference from nonessential brain regions and generally improves the brain’s information processing.

Moreover, this study shows that the right hand contraction leads to reduced activation only in the left hemisphere, but the left hand contraction has this effect in both hemispheres. This happens, the study authors suggest, probably because the right hemisphere has greater level of white matter and greater connectivity with the rest of the brain. Of course, the effects of this technique don’t last very long, but there should be some appreciable effect for at least 15 minutes.

3. Embodied cognition.
An entirely different explanation concerns the reason why different hardness of the ball has differing effects. The underlying concept here is that of the embodied cognition, which basically stands for the idea that our bodily experiences influence our thinking.

For example, other studies on embodied cognition show that we judge people to be more rigid if we touch a hard wooden block as opposed to a soft blanket or we drive a softer bargain in negotiations if we are seated in a soft chair (Ackerman et al., 2010). Predictably, squeezing a hard ball produces a bodily sensation of hardness, and this directs the thoughts toward more focused attention and deeper thinking. On the other hand, squeezing a soft ball feels easy and you can also sense malleable shapes of the ball; such bodily sensations of ease and malleability direct thoughts toward flexibility and multiple perspectives, and all of this helps you think of more divergent ideas.



Goldstein, A., Revivo, K., Kreitler, M., & Metuki, N. (2010). Unilateral muscle contractions enhance creative thinking. Psychonomic Bulletin & Review, 17 (6), 895-899. doi: 10.3758/PBR.17.6.895

Kim, J. (2015). Physical activity benefits creativity: Squeezing a ball for enhancing creativity. Creativity Research Journal, 27 (4), 328-333. doi: 10.1080/10400419.2015.1087258

Cross-Villasana, F., Gröpel P., Doppelmayr, M., Beckmann, J. (2015). Unilateral left-hand contractions produce widespread depression of cortical activity after their execution. PLoS ONE 10(12): e0145867. doi: 10.1371/journal.pone.0145867

Ackerman, J.M., Nocera, C.C., Bargh, J.A. (2010). Incidental haptic sensations influence social judgments and decisions. Science, 328, 1712-1715. doi: 10.1126/science.1189993

Micha Klootwijk/Bigstock

Squeezing a Rubber Ball May Boost Creative Thinking

Will Tumonis

Will Tumonis is an innovation consultant specializing in fundamentals of creative and adaptive thinking, especially in the context of complex problem solving and strategic decision-making. Previously he was an academic researcher working on behavioral and theoretical decision-making. He created the Nootomics project (, which aims to develop practical applications from behavioral research on creative thinking. He is also the founder of Swaycraft LLC, a consultancy which specializes in strategic social innovation.

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APA Reference
Tumonis, W. (2018). Squeezing a Rubber Ball May Boost Creative Thinking. Psych Central. Retrieved on November 30, 2020, from
Scientifically Reviewed
Last updated: 8 Jul 2018 (Originally: 21 Jun 2016)
Last reviewed: By a member of our scientific advisory board on 8 Jul 2018
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