Does restricting hand gestures impair mathematical reasoning?

Gestures are associated with powerful forms of understanding; however, their causative role in mathematics reasoning is less clear. We inhibit college students' gestures by restraining their hands, and examine the impact on language, recall, intuition, and mathematical justifications of geometric conjectures. We test four mutually exclusive hypotheses: (1) gestures are facilitative, through cognitive off-loading, verbal support, or transduction, (2) gestures are not facilitative, but being inhibited from gesturing increases cognitive demands, (3) gestures are a byproduct of reasoning processes that would take place with or without the gestures’ overt presence, and (4) gestures can cause learners to focus on concrete, salient representations, inhibiting abstraction. We find support for the third hypothesis, concluding that learners making or being inhibited from making gestures does not seem to impact their mathematical problem-solving, cognitive, or language processes. This suggests that being unable to overtly perform personally-generated gestures is not a hindrance to learners in this context; however this would not necessarily hold for directed or structured gestures. •Inhibiting hand gestures does not impair undergraduate performance on geometry tasks.•Inhibiting hand gestures does not impact language use in math justifications.•Gesture may be correlated with valid reasoning, but is not causatively related.•Making dynamic gestures was associated with improved insight and proof.