The nature of syntactic planning for language production may reflect language-specific processes, but an alternative is that syntactic planning is an example of more domaingeneral action planning processes. If so, language and non-linguistic action planning should have identifiable commonalities, consistent with an underlying shared system. Action and language research have had little contact, however, and such comparisons are therefore lacking. Here, we address this gap by taking advantage of a striking similarity between two phenomena in language and action production. One is known as syntactic priming-the tendency to re-use a recently produced sentence structureand the second is hysteresis-the tendency to re-use a previously executed abstract action plan, such as a limb movement. We examined syntactic priming/hysteresis in parallel language and action tasks intermixed in a single experimental session. Our goals were to establish the feasibility of investigating language and action planning within the same participants and to inform debates on the language-specific vs. domain-general nature of planning systems. In both action and language tasks, target trials afforded two alternative orders of subcomponents in the participant's response: in the language task, a picture could be described with two different word orders, and in the action task, locations on a touch screen could be touched in two different orders. Prime trials preceding the target trial promoted one of two plans in the respective domain. Manipulations yielded higher rates of primed behavior in both tasks. In an exploratory cross-domain analysis, there was some evidence for stronger priming effects in some combinations of action and language priming conditions than others. These results establish a method for investigating the degree to which language planning is part of a domain-general action planning system.

Dominant theories of language production suggest that word choice—lexical selection—is driven by alignment with the intended message: To talk about a young feline, we choose the most aligned word, kitten. Another factor that could shape lexical selection is word accessibility, or how easy it is to produce a given word (e.g., cat is more accessible than kitten). To test whether producers are also influenced by word accessibility, we designed an artificial lexicon containing high- and low-frequency words whose meanings correspond to compass directions. Participants in a communication game (total N = 181 adults) earned points by producing compass directions, which often required an implicit decision between a high- and low-frequency word. A trade-off was observed across four experiments; specifically, high-frequency words were produced even when less aligned with messages. These results suggest that implicit decisions between words are impacted by accessibility. Of all the times that people have produced cat, sometimes they likely meant kitten.

While many implicit decisions are the result of a trade-off, trade-offs in word use, such as whether a producer meant to convey a message more aligned with kitten despite saying a more accessible word like cat, are difficult to measure. To test the trade-off between message alignment and accessibility, we designed an artificial lexicon where word meanings corresponded to angles on a compass. In a novel language communication game, participants trained on some words more than others (high- vs low-frequency), and then earned points by producing words, often requiring an implicit decision between a high- vs low-frequency word. A trade-off was observed across four experiments, such that high-frequency words were produced even when less aligned with messages. Since high-frequency words are more accessible, these results suggest that implicit decisions between words are impacted by accessibility. Of all the times that people have said cat, many times they likely meant kitten.