The previous post discussed how squeezing a rubber ball may temporarily boost creative thinking. There is also a twist on this brain hack that may enhance memory. A 2013 study by Ruth Propper and her colleagues found that hand clenching may enhance your ability both to remember new ideas as well as recall existing information. However, the memory boost is likely to be small.
Also, the underlying neuroscientific model is a lot more dubious. This technique is based on the HERA model (Hemispheric Encoding/Retrieval Asymmetry), which basically says that left hemisphere is responsible for encoding of the new information and right hemisphere for retrieval. Further, an easy way to increase activation of the particular hemisphere is by clenching the contralateral hand (the hand of the opposite side). The HERA model has been heavily criticized as being based on a limited neuroscientific methodology. Furthermore, this technique for enhancing memory appears at odds, for example, with cortical deactivation research mentioned briefly in the last post.
Still, if you want to experiment with it to see if it gives you some benefit, it is pretty simple to perform:
- When you want to better soak up information (as when you’re reading an article or listening to a talk), squeeze a rubber ball or something similar with your right hand for about a minute. This will enhance the activation of the left hemisphere, which is supposed to help you better remember new information.
- Conversely, when you want to better retrieve various ideas (as when you need to recall ideas during a brainstorming session or while writing something), clench your left hand, which is supposed to enhance the activation of the right hemisphere.
Of course, clenching the wrong hand will backfire, but it is just as important to avoid clenching both hands at the same time.
 Ruth E. Propper, Sean E. McGraw, Tad. T. Brunye, and Michael Weiss, “Getting a Grip on Memory: Unilateral Hand Clenching Alters Episodic Recall,” PLoS ONE, 8, e62474. DOI:10.1371/journal.pone.0062474.
 Adrian M. Owen, “HERA Today, Gone Tomorrow?,” TRENDS in Cognitive Sciences, 7(9), 383-384 (2003). DOI: 10.1016/S1364-6613(03)00195-5.
For one, the HERA model is based almost entirely on functional neuroimaging data, and other neuroscientific methodologies don’t support it. For example, the HERA would predict that patients with unilateral frontal-lobe damage would have impaired either encoding or retrieval, depending on which hemisphere is damaged; yet, the studies don’t show any significant differences between patients with left and right sided frontal-lobe lesions.