This paper presents a computational model of how conversational participants collaborate in making referring expressions. The model is based on the planning paradigm. It employs plans for constructing and recognizing referring expressions and meta-plans for constructing and recognizing clarifications. This allows the model to account for the generation and understanding both of referring expressions and of their clarifications in a uniform framework using a single knowledge base.

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Participants in a discourse sometimes fail to understand one another, but, when aware of the problem, collaborate upon or negotiate the meaning of a problematic utterance. To address nonunderstanding, we have developed two plan-based models of collaboration in identifying the correct referent of a description: one covers situations where both conversants know of the referent, and the other covers situations, such as direction-giving, where the recipient does not. In the models, conversants use the mechanisms of refashioning, suggestion, and elaboration, to collaboratively refine a referring expression until it is successful. To address misunderstanding, we have developed a model that combines intentional and social accounts of discourse to support the negotiation of meaning. The approach extends intentional accounts by using expectations deriving from social conventions in order to guide interpretation. Reflecting the inherent symmetry of the negotiation of meaning, all our models can act as both speaker and hearer, and can play both the role of the conversant who is not understood or misunderstood and the role of the conversant who fails to understand.

Speakers often repeat the first word of major constituents, as in, ‘‘I uh I wouldn’t be surprised at that.’ ’ Repeats like this divide into four stages: an initial commitment to the constituent (with ‘‘I’’); the suspension of speech; a hiatus in speaking (filled with ‘‘uh’’); and a restart of the constituent (‘‘I wouldn’t...’’). An analysis of all repeated articles and pronouns in two large corpora of spontaneous speech shows that the four stages reflect different principles. Speakers are more likely to make a premature commitment, immediately suspending their speech, as both the local constituent and the constituent containing it become more complex. They plan some of these suspensions from the start as preliminary commitments to what they are about to say. And they are more likely to restart a constituent the more their stopping has disrupted its delivery. We argue that the principles governing these stages are general and not specific to repeats.

The MRC machine usable dictionary contains 150837 words with up to 26 linguistic and psycholinguistic attributes for each. The attributes are from sources that are publicly available, but difficult to obtain and structure into a single dictionary. Three utility programs are described which permit the selection of words defined by a set of specified attribute values, and the attribute values for a set of specified words. These programs permit the construction of word sets for psycholinguistic experiments which control for the attributes specified in the dictionary. The dictionary may also be of use to researchers in artificial intelligence and computer science who require psychological and linguistic descriptions of words. - 2 - Those wishing to construct word sets as stimuli for psycholinguistic experiments must take into account a large number of characteristics of the words (see Cutler, 1981; Whaley, 1978). The Medical Research Council (MRC) Psycholinguistic Database version 1, was...

We formalize and extend the contribution model of Clark and Schaefer (1987, 1989) so that it can be represented computationally; we then present a method for combining the turns of two individual agents into one incrementally determined, coherent representation of the processes of dialog. This representation is intended to approximate what a participant might represent about the dialog so far, for the immediate purpose of referring, making contextual inferences, and repairing problems of understanding, as well as for the longer term purpose of storing the products of dialog in memory. Such an approach, we argue, is necessary for enabling a computer-based partner to converse in a way that seems natural to a human partner. Introduction Dialog is a collective activity that is managed in real time by agents with limited attentional, computational, and knowledge resources. Even when two agents are rational and cooperative, inhabit the same location, speak the same language, sh...

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A central concern of psycholinguistic research is explaining the relative ease or difficulty involved in processing words. In this thesis, we explore the connection between lexical processing effort and measurable properties of the linguistic environment. Distributional information (information about a word's contexts of use) is easily extracted from large language corpora in the form of co-occurrence statistics. We claim that such simple distributional statistics can form the basis of a parsimonious model of lexical processing effort.

Dialogue has its origins in joint activities, which it serves to coordinate. Joint activities, in turn, usually emerge in hierarchically nested projects and subprojects. We propose that participants use dialogue to coordinate two kinds of transitions in these joint projects: vertical transitions, or entering and exiting joint projects; and horizontal transitions, or continuing within joint projects. The participants help signal these transitions with project markers, words such as uh-huh, m-hm, yeah, okay, or all right. These words have been studied mainly as signals of listener feedback (back-channel signals) or turn-taking devices (acknowledgment tokens). We present evidence from several types of well-defined tasks that they are also part of a system of contrasts specialized for navigating joint projects. Uh-huh, m-hm and yeah are used for horizontal transitions, and okay and all right for vertical transitions.

The proposal examined here is that speakers use uh and um to announce that they are initiating what they expect to be a minor (uh), or major (um), delay in speaking. Speakers can use these announcements in turn to implicate, for example, that they are searching for a word, are deciding what to say next, want to keep the floor, or want to cede the floor. Evidence for the proposal comes from several large corpora of spontaneous speech. The evidence shows that speakers monitor their speech plans for upcoming delays worthy of comment. When they discover such a delay, they formulate where and how to suspend speaking, which item to produce (uh or um), whether to attach it as a clitic onto the previous word (as in "and-uh"), and whether to prolong it. The argument is that uh and um are conventional English words, and speakers plan for, formulate, and produce them just as they would any word.