Researchers agree that comprehenders regularly predict upcoming language, but they do not always agree on what prediction is (and how to differentiate it from integration) or what constitutes evidence for it. After defining prediction, we show that it occurs at all linguistic levels from semantics to form, and then propose a theory of which mechanisms comprehenders use to predict. We argue that they most effectively predict using their production system (i.e., prediction-by-production): They covertly imitate the linguistic form of the speaker's utterance and construct a representation of the underlying communicative intention. Comprehenders can then run this intention through their own production system to prepare the predicted utterance. But doing so takes time and resources, and comprehenders vary in the extent of preparation, with many groups of comprehenders (non-native speakers, illiterates, children, and older adults) using it less than typical native young adults. We thus argue that prediction-by-production is an optional mechanism, which is augmented by mechanisms based on association. Support for our proposal comes from many areas of research (electrophysiological, eye-tracking, and behavioral studies of reading, spoken language processing in the context of visual environments, speech processing, and dialogue). (PsycINFO Database Record

In two experiments we provided evidence for a joint interference effect in picture naming. Participants took longer to name pictures when they believed that their partner concurrently named pictures than when they believed their partner was silent (Experiment 1) 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. These findings are consistent with the idea that speakers represent whether another speaker is preparing to speak, but not what they are preparing to say.

During conversation, there is often little gap between interlocutors' utterances. In two pairs of experiments, we manipulated the content predictability of yes/no questions to investigate whether listeners achieve such coordination by (i) preparing a response as early as possible or (ii) predicting the end of the speaker's turn. To assess these two mechanisms, we varied the participants' task: They either pressed a button when they thought the question was about to end (Experiments 1a and 2a), or verbally answered the questions with either yes or no (Experiments 1b and 2b). Predictability effects were present when participants had to prepare a verbal response, but not when they had to predict the turn-end. These findings suggest content prediction facilitates turn-taking because it allows listeners to prepare their own response early, rather than because it helps them predict when the speaker will reach the end of their turn.

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It has been suggested that intra- and inter-speaker variability in speech are correlated. Interlocutors have been shown to converge on various phonetic dimensions. In addition, speakers imitate the phonetic properties of voices they are exposed to in shadowing, repetition, and even passive listening tasks. We review three theoretical accounts of speech imitation and convergence phenomena: (i) the Episodic Theory (ET) of speech perception and production (Goldinger, 1998); (ii) the Motor Theory (MT) of speech perception (Liberman and Whalen, 2000; Galantucci et al., 2006); (iii) Communication Accommodation Theory (CAT; Giles and Coupland, 1991; Giles et al., 1991). We argue that no account is able to explain all the available evidence. In particular, there is a need to integrate low-level, mechanistic accounts (like ET and MT), and higher-level accounts (like CAT). We propose that this is possible within the framework of an integrated theory of production and comprehension (Pickering and Garrod, 2013). Similarly to both ET and MT, this theory assumes parity between production and perception. Uniquely, however, it posits that listeners simulate speakers' utterances by computing forward-model predictions at many different levels, which are then compared to the incoming phonetic input. In our account phonetic imitation can be achieved via the same mechanism that is responsible for sensorimotor adaptation; i.e., the correction of prediction errors. In addition, the model assumes that the degree to which sensory prediction errors lead to motor adjustments is context-dependent. The notion of context subsumes both the preceding linguistic input and non-linguistic attributes of the situation (e.g., the speaker's and listener's social identities, their conversational roles, the listener's intention to imitate).

a b s t r a c tRecent social-cognitive research suggests that the anticipation of co-actors' actions influences people's mental representations. However, the precise nature of such representations is still unclear. In this study we investigated verbal joint representations in a delayed Stroop paradigm, where each participant responded to one color after a short delay. Participants either performed the task as a single actor (singleaction, Experiment 1), or they performed it together (joint-action, Experiment 2). We investigated effects of co-actors' actions on the ERP components associated with perceptual conflict (Go N2) and response selection (P3b). Compared to single-action, joint-action reduced the N2 amplitude congruency effect when participants had to respond (Go trials), indicating that representing a co-actor's utterance helped to dissociate action codes and attenuated perceptual conflict for the responding participant. Yet, on NoGo trials the centro-parietal P3 (P3b) component amplitude increased for joint-action, suggesting that participants mapped the stimuli onto the co-actor's upcoming response as if it were their own response. We conclude that people represent others' utterances similarly to the way they represent their own utterances, and that shared perception-action codes for self and others can sometimes reduce, rather than enhance, perceptual conflict.

Dialog partners coordinate with each other to reach a common goal. The analogy with other joint activities has sparked interesting observations (e.g., about the norms governing turn-taking) and has informed studies of linguistic alignment in dialog. However, the parallels between language and action have not been fully explored, especially with regard to the mechanisms that support moment-by-moment coordination during language use in conversation. We review the literature on joint actions to show (i) what sorts of mechanisms allow coordination and (ii) which types of experimental paradigms can be informative of the nature of such mechanisms. Regarding (i), there is converging evidence that the actions of others can be represented in the same format as one’s own actions. Furthermore, the predicted actions of others are taken into account in the planning of one’s own actions. Similarly, we propose that interlocutors are able to coordinate their acts of production because they can represent their partner’s utterances. They can then use these representations to build predictions, which they take into account when planning self-generated utterances. Regarding (ii), we propose a new methodology to study interactive language. Psycholinguistic tasks that have traditionally been used to study individual language production are distributed across two participants, who either produce two utterances simultaneously or complete each other’s utterances.

Switching language is costly for bilingual speakers and listeners, suggesting that language control is effortful in both modalities. But are the mechanisms underlying language control similar across modalities? In this study, we attempted to answer this question by testing whether bilingual speakers incur a cost when switching to a different language than the one just used by their interlocutor. Pairs of unbalanced Dutch (L1) -English (L2) bilinguals took turns naming pictures in a pure Dutch, a pure English, and a mixed-language block. In the mixed block, one participant (Switching Participant) voluntarily switched between Dutch and English, whereas the other (NonSwitching Participant) named all pictures in Dutch. Within the mixed block, the Non-Switching participant took longer to name pictures when the Switching participant's response on the preceding trial had been in English rather than Dutch, and this local switch cost was larger the more the NonSwitching participant was proficient in English. Additionally, there was strong cross-person itemlevel interference: The Non-Switching participant named pictures more slowly in Dutch if the Switching participant had previously named those same pictures in English rather than Dutch.These findings indicate that comprehension of utterances produced by another speaker in L2 makes subsequent production of L1 utterances more costly. We interpret this as evidence that language control mechanisms are shared between comprehension and production, and specifically that bottom-up factors have a considerable influence on language selection processes in both modalities.Keywords: voluntary language switching; joint task; comprehension; production. Bilinguals often switch between their languages, especially during informal conversations with other bilinguals (e.g., Grosjean, 2001). However, switching language leads to slower responses in laboratory tasks, both when bilinguals produce a switch (e.g., Meuter & Allport, 1999) and when they comprehend a switch (e.g., Thomas & Allport, 2000). Showing that language switches are costly to process in comprehension and to execute in production is relevant for theories of bilingual dialogue since bilingual interlocutors tend to switch between their shared languages within their respective turns (e.g., Grosjean, 2001). But furthermore, in some bilingual conversations, each interlocutor consistently uses only one language (normally her first language, L1), so that switches occur between turns (if the two bilinguals have different L1's). Thus, bilinguals may also be confronted with switches from comprehension (of their interlocutor's utterance) to production (of their own utterance).The goal of the present study was to investigate whether comprehension of utterances produced by another speaker in one's second language (L2) makes subsequent production of L1 utterances more costly. As we explain below, the occurrence of cross-person switch costs is compatible with theories of bilingual lexical selection that assume shared language contro...