Proceedings of the Annual Meeting of the Cognitive Science Society

Speakers are known to insert optional words when upcoming material is difficult. In three studies, we investigated howphonological interference and motor planning difficulty affect production choices. First, analyses of the spoken COCAcorpus (¿100m words) showed lower use of [optional-that] in relative clauses following a that determiner (that boy [that]we saw) than following other determiners (this boy [that] we saw). Second, a sentence recall study confirmed numericallylower rates of optional-that use and more recall/production errors in the presence of a homophonous that determinercompared with sentences with other determiners. These two studies suggest phonological interference reduces the planningbenefits of optional-that. Third, in a separate sentence recall study, we demonstrated optional-that use increases withmotor planning difficulty (concurrent finger tapping). Together, these results demonstrate that speakers balance multipleconstraints when planning speech, and that both phonological interference and concurrent tasks affect language productionchoices.