Abstract
Humans have created and maintained an exponentially large and sophisticated behavioral corpus over evolutionary
time. In no small part this was achieved due to our tendency to imitate behaviours rather than to emulate
outcomes. This tendency, however, can lead to inefficiency and redundancy in our behavioral repertoires. Drawing
on evidence from multiple fields of psychology, we propose two novel competing hypotheses. The ‘catalyst
hypothesis’ suggests that low (but not high) proportions of ritualized gesture in instrumental action sequences will
improve subsequent recall of the entire action sequence (without itself enhancing the instrumental utility of the
sequence). Conversely, the ‘cost hypothesis’ suggests that increasing proportions of ritualized gesture will impair
recall, due to the introduction of cognitive load. The null hypothesis states that ritualized gestures are neither
beneficial nor costly. In a pre‐registered experiment, we presented participants with multiple versions of two
complicated 2‐minute action sequences in which we varied the proportion of ritualized gesture. We then quantified
the influence ritualized gesture had on recall for individuals gestures, overall outcomes, and described detail. We
found clear evidence that high proportions of ritualized gestures impair recall for individual gestures and overall
success, and weak evidence that low proportions increase overall success. At present, we may reject the null, but
cannot rule out either of our competing hypotheses. We discuss potential implications for cultural evolution, and
generate competing predictions that allow for adjudication between Ritual Modes theory (Whitehouse, 2004) and
the ‘Cognitive Resource Depletion’ account of Religious Interaction (Schjoedt et al., 2013). All files (including data
and syntax) are freely available at https://osf.io/spz68/.