The unilateral contractions procedure (i.e., squeezing a ball with one hand) supposedly enhances a wide variety of cognitive functions, from episodic recall to choking under pressure. The practicality and affordability of this procedure makes it highly appealing. But does it work? We addressed this question by testing whether intermittent and sustained unilateral contractions shifted a well-supported hemispheric asymmetry: visuospatial attention. Based on prior research, contracting the left (or right) hand should lead baseline scores on the landmark task—a visuospatial attention measure—to deviate further left (or right). We meta-analysed the results of our six experiments and showed that the unilateral contractions procedure, particularly with intermittent contractions, does not reliably shift landmark task scores measured during (Experiments 4–6) or after (Experiments 1–3 & 6) performing unilateral contractions. Although we question if and how unilateral contractions activate the contralateral hemisphere, Experiment 6 provided some support for the utility of sustained contractions.

据推测，单侧收缩程序（即，用一只手挤压球）可以增强多种认知功能，从间歇性回忆到压力性窒息。该程序的实用性和可承受性使其极具吸引力。但这有效吗？我们通过测试间歇性和持续性单侧收缩是否转移了支撑良好的半球不对称性：视觉空间注意力来解决这个问题。根据先前的研究，收缩左手（或右手）应在路标任务（视觉空间注意措施）上领先基线得分，以进一步偏离左手（或右手）。我们对六个实验的结果进行了荟萃分析，结果表明，单侧收缩过程，尤其是间歇性收缩，不能可靠地移动在执行单侧收缩期间（实验4–6）或之后（实验1–3和6）测量的界标任务分数。尽管我们质疑单侧收缩是否以及如何激活对侧半球，但实验6为持续收缩的实用性提供了一些支持。