Achieving ‘implicit’ common ground: alignment through priming

Some of the history and scope of research on the priming process will be examined in detail later in this inquiry (see Chapter 6.3). However, it is the work of Branigan, Pickering & Cleland (2000) that at this point plays an essential role in the narrative, by specifically assessing the ability of interlocutors to co-ordinate, not just their reference strategies, but also the syntactic structures they use during dialogue.

Quoting the benefits to both Speaker and Hearer that result from semantic and lexical co-ordination, Branigan et al propose that the same advantages should also hold with respect to other linguistic levels, such as grammatical structure. Furthermore – and very importantly – they demonstrate that the linguistic priming mechanism is bi- directional: participants in a dialogue will display co-ordination of grammatical form by using a particular form if they have heard the other speaker use it. This is

demonstrated in a series of experiments in which participants take turns to describe scenes that lend themselves to alternative syntactic constructions (e.g. double object

vs. prepositional object constructions, as in ‘Give Bill the book’ vs ‘Give the book to Bill’). ‘We found a dramatic tendency for speakers to produce a syntactic form that they had just heard the other participant use: When the verb remained the same, they produced 55% more syntactically co-ordinated responses than non-co-ordinated responses; when it differed, they produced 26% more co-ordinated than non-co- ordinated responses’ (Branigan et al, 2000: B20).

Results such as these mark a significant advance on earlier investigations of syntactic priming, where the effect demonstrated is one-way only (i.e. production of a given grammatical form increased the probability of the spontaneous production of the same form; cf Bock, 1986; 360), and they lead to a significant conclusion: ‘Our finding…’ Branigan et al continue, ‘is informative about the nature of the language processing system. It demonstrates that there are shared syntactic representations underlying comprehension and production, and moreover that these representations are activated during spontaneous dialogue’ (ibid: B22)

Importantly in the context of my own inquiry, a suggested consequence of this sharing process is reduction of speaker effort. As Branigan et al point out (ibid: B15), speakers can, by coordinating grammatical form, reduce the computational load associated with the syntactic processing of their contributions: thus, ‘when they have a choice between alternative grammatical structures to express a meaning, speakers should tend to use one or other form if the other speaker has just employed that form.’ But this is not the only implication of Branigan et al’s findings. Owing to the parity of representation that they indicate between the functions of

comprehension and production, the way has been opened to devising a model of dialogue in which direct and automatic ‘tight coupling’ – enabled by priming – can be hypothesized at every level, from the articulatory to the situational, with the result that interlocutor misinterpretation rates are reduced. Furthermore, the difference observed by Branigan et al between the priming effect produced in same-verb and different-verb exchanges (i.e. the stronger syntactic repetition effect when prime and target utterances use the same verb) supports the idea that there is, not just horizontal alignment across the levels, but also vertical alignment between them. ‘This

thinking,’ Pickering explains later, ‘illustrates a principle of the interactive-alignment model: alignment at one level (in this case, lexical alignment) enhances alignment at

other levels (in this case, grammatic alignment)12. This means that alignment can “percolate up” through the different linguistic levels to the critical level of the situation model’ (Pickering, 2006: 736). And this vertical ‘percolation’, linked with its accompanying horizontal process, can thus ensure that partners use similar language, articulated in similar fashion, to communicate with each other about the same thing, such as the same square in the Garrod & Anderson maze.

A major corollary of Pickering & Garrod’s alignment-via-priming argument lies in its impact on the whole theoretical area of mutual understanding in its various aspects: common knowledge, mutual belief/grounding, audience modelling, and mutual manifestness. If, as their model suggests, alignment between two

interlocutors takes place automatically, the need for deliberate, conscious audience modelling – a ‘decision box’ in which a Speaker decides what is most appropriate to say to a given Addressee – becomes substantially diminished. In its place, Pickering & Garrod propose a weaker concept, that of ‘implicit’ (rather than ‘full’, i.e.

Clarkian) common ground. This, in fully interactive dialogue at least, gives both participants an extensive grasp of their interlocutor’s knowledge state because – through the automatic alignment process – it makes information that was accessible to one party accessible to the other13.

[It] is effective because an interlocutor builds up a situation model that contains (or at least foregrounds) information that the interlocutor has processed (either by producing that information or comprehending it). But because the other interlocutor is also present, he comprehends what the first interlocutor produces and vice versa. This means that both interlocutors foreground the same information, and therefore tend to make the same additions to their situation models… As the conversation proceeds and more information is added, the amount of information that is not shared will be reduced. Hence, the implicit common ground will be extended. Notice that there is no need to infer the situation model of one’s interlocutor.

(op cit: 178)

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They point out that alignment also takes place at the articulation level, with speakers echoing each other’s accents, speech rates, and the extent to which they shorten repeated expressions.

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Garrod & Pickering, in a later exposition of their 2004 alignment model, further clarify the distinction between the two ‘grounding’ concepts. Clark, they point out, argues that interlocutors use various strategies to accumulate common ground, which ‘refers to all the information that both interlocutors believe to be shared by themselves and their conversational partner. This is actually a stricter notion than alignment, which merely refers to the information that happens to be shared’ (Garrod & Pickering, 2007: 443).

Normal conversation, Pickering & Garrod continue, therefore does not routinely require modelling the interlocutor’s mind, even though it may give the impression of doing so: an effect first noted, they point out, in Brown & Dell’s 1987 study of production-comprehension relationships.14 Instead, the overlap between participants’ representations will be big enough for a speaker’s specific contribution either to set off appropriate changes in the listener’s representation, or to trigger the interactive repair process: ‘The listener will retain an appropriate model of the speaker’s mind,

because, in all essential respects, it is the listener’s representation as well [authors’

emphasis]’ (ibid: 180)

A further set of implications concerns the ease or otherwise with which Speakers fulfil their role. Such massive priming, Pickering & Garrod suggest, can greatly enhance language production, via the prior activation of relevant linguistic

representations (e.g. lexical and syntactic representations). While speakers do not usually just aim to repeat what’s been said to them, they will tend – thanks to the activation of their syntactic and lexical representations created by previous utterances – to repeat the syntactic and lexical forms used by an interlocutor, and thus become aligned with him. It follows from this that, in both sentence recall and dialogue, ‘very much less choice’ needs to be made than in monologue: an effect suggested earlier by Branigan et al. ‘The decisions that occur in language production (e.g. choice of word or structure) are to a considerable extent driven by the context and do not need to be a burden for the speaker. Thus, they are at least partly stimulus-driven rather than entirely internally generated, in contrast to accounts like Levelt (1989)’ (ibid: 183).

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In an investigation of how, or whether, speech production is adapted to comprehension, this concludes that, in the main, such adaptation takes place neither because speakers model their listeners’ information needs nor because they remember their own comprehension experiences in the same linguistic context. Instead, Brown & Dell suggest, the key mechanism here is a process of conceptual constraint, whereby adaptation takes place because ‘analogous processes underly [sic] translating a conceptual structure to a text and deriving a conceptual structure from a text’ (Brown & Dell, 1987: 452). According to this listener-independent account, the way a Speaker processes a text as a ‘Hearer’ (actually, in this case, a ‘Reader’) influences the way he then reproduces it in speech. An unexpected, and therefore salient, element in the text will feature in the spoken summary, with the

2.4.5 Challenges and developments

Pickering & Garrod’s 2004 model of priming-driven dialogue has not gone unchallenged. One interesting objection that can be raised concerns a potential conflict between Pickering & Garrod’s treatment of dialogue production and comprehension as an automatic, low-level ‘mechanistic’ process involving no inferences about interlocutors’ mental states, and a pragmatic approach such as Relevance Theory, which treats utterance comprehension as an inferential process resulting in the attribution of a complex mental state – a Gricean speaker’s meaning. In the context of my own inquiry – which is broadly sympathetic to relevance theory but sees the alignment model as making a major contribution – this argument might seem to present a considerable problem; and indeed, Pickering & Garrod’s search for an alternative to Clark’s broadly Gricean approach was largely based on their desire to avoid what they saw as the costly modelling of interlocutors’ mental states.

However, as Sperber & Wilson (2002) point out, the attribution of mental states (‘theory of mind’) itself can be conceived of in two ways. It might be thought of as a conscious, reflective reasoning process of the type described in Grice’s famous ‘working-out schema’ for implicatures: ‘He said that P; he could not have done this unless he thought that Q; he knows (and knows that I know that he knows) that I will realise that it is necessary to suppose that Q; he has done nothing to stop me thinking that Q; so he intends me to think, or is at least willing for me to think, that Q’ (Grice, 1989: 30-31).

This seems to be the type of process that Pickering & Garrod have in mind in their debate with Clark. Alternatively, it might be an automatic, modularised inference process that takes place below the level of consciousness, and as such is relatively fast and effort-free. Sperber & Wilson argue that mental state attributions in general are carried out by an inferential ‘mindreading’ module with a variety of sub-modules, one of which is specifically dedicated to comprehension. The type of low-level priming processes discussed by Pickering & Garrod are quite compatible with this modular approach to inference, and I will argue that they can contribute to it in worthwhile ways.

The relevance-theoretic approach to comprehension is therefore both inferential and mechanistic, in the sense that the inferences carried out by the relevance-guided comprehension module are as spontaneous and automatic as the priming mechanism that supports the alignment model of dialogic interaction proposed by Pickering & Garrod. It is then an empirical question how much of utterance production and comprehension – which is treated on both sides as typically fast, automatic and unconscious – is purely a matter of activation (e.g. by priming), and how much is properly inferential. In what follows, I will focus mainly on the activation side, but I assume, unlike Pickering & Garrod (though in common with most people working in pragmatics), that a substantial element of inference is also necessarily involved.

Other grounds on which Pickering & Garrod’s model has been criticised include its assumption of production/comprehension parity of representation, and its apparent rejection of an explicit audience modelling process as the basis for communication. One alternative proposed is that of a radically different method of expressing

dialogic coordination, via a grammar formalism involving a common, parsing-based architecture for both comprehension and production (Kempson et al, 2001;

Kempson, 2004: 202). And Pickering & Garrod themselves acknowledge limitations to their theory.

They accept, for instance, that alignment on the basis of ‘implicit common ground’ does not meet all communication requirements, simple and resource-effective though this is claimed to be; as a fail-safe device, they propose the use of full common ground, with concomitant inferencing about an audience, at moments when

alignment has failed to clarify a reference. Use of full common ground is also likely when one interlocutor wants to deceive or withhold information from another, or when a Speaker wants deliberately to influence an Addressee in some way. ‘It is important to stress that we are proposing interactive alignment as the primitive mechanism underlying dialogue, not a replacement for the more complicated strategies that conversationalists may employ on occasion’ (ibid: 180).

Another disclaimer is perhaps more fundamental. Although Pickering & Garrod cite a wide range of examples of linguistic priming, they concede that ‘fully specified theories of how much priming operates are not available for all levels’ (ibid:

176). Indeed, the concept of automatic alignment through priming (like that of

automatic audience modelling, to which it leads) has been another target of criticism.

One issue of particular concern is an apparent methodological gap between priming at lower linguistic levels and priming at the level of the situation model. As

explained by Warren & Rayner (2004), the objection here rests on the contention that phonological, lexical, and syntactic priming are similar in that representations primed are an ‘inalienable part’ of a message structure, while semantic priming, though less direct, can also draw on representations that are generally similar. Situation models, however, are different: there is no direct priming channel here as there is between the physical aspects of a message. Nor yet is the looser semantic priming pattern

applicable, as ‘individuals do not necessarily begin dialogue with similar situation representations. Therefore the priming link between individuals’ situation models in the interactive alignment model must be of a different sort from the priming channels between other representations… More research into the details of situation model priming and the complex interplay of priming and inhibition between different levels of representation will be necessary in order to fully specify the operation of the model and to evaluate its ascribed simplicity’ (Warren & Rayner, 2004: 211).

A further disclaimer made by Pickering & Garrod in 2004 concerns the upper limit of their model itself. Does the process of alignment that they hypothesize go beyond the level of the situation (e.g. who, what, why, when, etc) to that of content choice itself? Importantly in the context of my own inquiry, they here draw a dividing line:

Our contention is that interactive alignment (and in particular the automatic alignment channels) affects the structures used in production and interpretation rather than directly determining the content [authors’ emphasis] of production and interpretation. In other words, we assume that alignment provides an explanation of the manner [my emphasis] in which interlocutors produce and interpret contributions. So we propose that alignment channels only produce a direct link between the structures that the interlocutors use in language

processing. Hence, the alignment process is automatic and direct, even though it does not determine exactly what the speaker produces (as this depends on his long-term knowledge) or how the addressee interprets what he hears “beyond” the level of the situation model.

In later work, Pickering & Garrod rise to these challenges. Interestingly, they later re-label the main mechanism supporting alignment as ‘a process of automatic (nonconscious and effortless) imitation at different linguistic levels’ (Garrod & Pickering, 2009: 296; authors’ emphasis)15. However, they also suggest ways in which their automatic alignment model could be developed to include both linguistic and non-linguistic mechanisms, and review some accounts (Garrod & Pickering, 2007) of how these may operate. In addition to the priming-driven processes of linguistic alignment described in their 2004 model, they suggest that alignment may take place in a variety of ways: via beliefs about one’s interlocutor; via imitation in non-linguistic dimensions (e.g. facial expressions); via tacit agreement between interlocutors (such as the ‘conceptual pact’ described by Brennan & Metzing; cf Chapter 2.3.3); via feedback; and via physical co-presence. They also explore the extent to which these may be either automatic or ‘strategic’: i.e. choices explicitly made on the basis of inferences about the extent of common ground existing between a speaker and his interlocutor.

Amongst these potential alignment mechanisms, the first – the appeal to beliefs about one’s interlocutor – bridges the gap between automaticity and explicit audience modelling. It also marks a return on Garrod & Pickering’s part to the notion of priming or, rather, of the processes that possibly underlie it. No doubt, they say, speakers make some reasoned decisions about how to produce descriptions on the basis of what they believe their audience to know. ‘But their choices may also reflect automatic resonance processes … [which] could arise from the prior

association of particular types of addressee with particular expressions, the activation of such types of addressee as a result of the interaction, and the subsequent activation of those expressions’ (Garrod & Pickering, 2007: 444). Here they cite the work of Horton & Gerrig (2005) on the role played in achieving common ground, not by expressly-formulated communication strategies, but by ordinary memory processes acting on ordinary memory representations.

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A re-labelling that may seem to contain a contradiction in terms, as the usual interpretation of imitation involves adoption of the same goals – which is not the case in the ‘nonconscious and effortless’ process described here of copying form, such as grammatical choice or speech rate (cf also Garrod & Pickering, 2007).

Suggesting that the process of audience design, while important, remains ‘woefully underspecified’, Horton & Gerrig propose that the explanation of what appears to be common ground is the outcome of a memory process termed ‘resonance’: a ‘fast, passive, and effort-free mechanism in which cues in working memory interact in parallel with information residing in long-term memory’ (Horton & Gerrig, 2005a: 10) and which, by a process of association, brings a wide range of information within cognitive reach. And, they continue, where conversational situations are concerned, ‘we suggest that other individuals function as highly salient cues to make

information with which they are associated ready.’

Thus, apparent instances of calculated audience design on the part of a Speaker may in fact be the outcome of partner-specific memory processes that make information closely connected with an interlocutor accessible during language use. Horton & Gerrig test this claim by comparing the way in which different participants in a matching task are exposed to information about their partners, and their subsequent conversations with them. The results show that speakers were more likely to adjust their utterances to their partners’ communicative needs when each addressee could be associated with a unique referential context and, therefore, those in the

experimental group ‘were able to exhibit more evidence of audience design because the memory representations required for audience design were more readily

accessible during the period of time they allowed themselves to plan their utterances’ (Horton & Gerrig, 2005b: 139). They also suggest that this resonance-based model can be extended to accommodate, not just the automatic referencing of information held in common by interlocutors, but also the automatic message formation that can take place between them – the words they use: ‘We expect that addressees would