Repetition Parallels in Language and Motor Action: Evidence From Tongue Twisters and Finger Fumblers

We investigated similarities in language and motor action plans by comparing errors in parallel speech and manual tasks. For the language domain, we adopted the “tongue twister” paradigm, while for the action domain, we developed an analogous key-pressing task, “finger fumblers.” Our results show that both language and action plans benefit from reusing segments of prior plans: when onsets were repeated between adjacent units in a sequence, the error rates decreased. Our results also suggest that this facilitation is most effective when the planning scope is limited, that is, when participants plan ahead only to the next immediate units in the sequence. Alternatively, when the planning scope covers a wider range of the sequence, we observe more interference from the global structure of the sequence that requires changing the order of repeated units. We point to several factors that might affect this balance between facilitation and interference in plan reuse, for both language and action planning. Our findings support similar domain-general planning principles guiding both language production and motor action.