Interference in joint picture naming

In 4 experiments we showed that picture naming latencies are affected by beliefs about the task concurrently performed by another speaker. Participants took longer to name pictures when they believed that their partner concurrently named pictures than when they believed their partner was silent (Experiments 1 and 4) or concurrently categorized the pictures as being from the same or from different semantic categories (Experiment 2). However, picture naming latencies were not affected by beliefs about what one's partner said, as it did not matter whether participants believed their partner produced the same utterance, or an utterance that differed by ordering (Experiments 1 and 2) or lexical content (Experiments 3 and 4). These findings are consistent with the proposal that speakers represent whether another speaker is preparing to speak but not what they are preparing to say