Speakers Plan Research Articles

Individual differences in the scope of speech planning: evidence from eye-movements

abstractPrevious research has demonstrated that the scope of speakers’ planning in language production varies in response to external forces such as time pressure. This susceptibility to external pressures indicates a flexibly incremental production system: speakers plan utterances piece by piece, but external pressures affect the size of the pieces speakers buffer. In the current study, we explore internal constraints on speech planning. Specifically, we examine whether individual differences in working memory predict the scope and efficiency of advance planning. In our task, speakers described picture arrays to partners in a matching game. The arrays sometimes required speakers to note a contrast between a sentence-initial object (e.g., a four-legged cat) and a sentence-final object (e.g., a three-legged cat). Based on prior screening, we selected participants who differed on verbal working memory span. Eye-movement measures revealed that high-span speakers were more likely to gaze at the contrasting pictures prior to articulation than were low-span speakers. As a result, high-span speakers were also more likely to reference the contrast early in speech. We conclude that working memory plays a substantial role in the flexibility of incremental speech planning.

Inter-subject variability modulates phonological advance planning in the production of adjective-noun phrases

The literature on advance phonological planning in adjective-noun phrases (NPs) presents diverging results: while many experimental studies suggest that the entire NP is encoded before articulation, other results favor a span of encoding limited to the first word. Although cross-linguistic differences in the structure of adjective-NPs may account for some of these contrasting results, divergences have been reported even among similar languages and syntactic structures. Here we examined whether inter-individual differences account for variability in the span of phonological planning in the production of French NPs, where previous results indicated encoding limited to the first word. The span of phonological encoding is tested with the picture-word interference (PWI) paradigm using phonological distractors related to the noun or to the adjective of the NPs. In Experiment 1, phonological priming effects were limited to the first word in adjective NPs whichever the position of the adjective (pre-nominal or post-nominal). Crucially, phonological priming effects on the second word interacted with speakers' production speed suggesting different encoding strategies for participants. In Experiment 2, we tested this hypothesis further with a larger group of participants. Results clearly showed that slow and fast initializing participants presented different phonological priming patterns on the last element of adjective-NPs: while the first word was primed by a distractor for all speakers, only the slow speaker group presented a priming effect on the second element of the NP. These results show that the span of phonological encoding is modulated by inter-individual strategies: in experimental paradigms some speakers plan word by word whereas others encode beyond the initial word. We suggest that the diverging results reported in the literature on advance phonological planning may partly be reconciled in light of the present results.

Ways of looking ahead: Hierarchical planning in language production

It is generally assumed that language production proceeds incrementally, with chunks of linguistic structure planned ahead of speech. Extensive research has examined the scope of language production and suggests that the size of planned chunks varies across contexts (Ferreira & Swets, 2002; Wagner & Jescheniak, 2010). By contrast, relatively little is known about the structure of advance planning, specifically whether planning proceeds incrementally according to the surface structure of the utterance, or whether speakers plan according to the hierarchical relationships between utterance elements. In two experiments, we examine the structure and scope of lexical planning in language production using a picture description task. Analyses of speech onset times and word durations show that speakers engage in hierarchical planning such that structurally dependent lexical items are planned together and that hierarchical planning occurs for both direct and indirect dependencies.

Neural representations and mechanisms for the performance of simple speech sequences.

Speakers plan the phonological content of their utterances before their release as speech motor acts. Using a finite alphabet of learned phonemes and a relatively small number of syllable structures, speakers are able to rapidly plan and produce arbitrary syllable sequences that fall within the rules of their language. The class of computational models of sequence planning and performance termed competitive queuing models have followed K. S. Lashley [The problem of serial order in behavior. In L. A. Jeffress (Ed.), Cerebral mechanisms in behavior (pp. 112-136). New York: Wiley, 1951] in assuming that inherently parallel neural representations underlie serial action, and this idea is increasingly supported by experimental evidence. In this article, we developed a neural model that extends the existing DIVA model of speech production in two complementary ways. The new model includes paired structure and content subsystems [cf. MacNeilage, P. F. The frame/content theory of evolution of speech production. Behavioral and Brain Sciences, 21, 499-511, 1998 ] that provide parallel representations of a forthcoming speech plan as well as mechanisms for interfacing these phonological planning representations with learned sensorimotor programs to enable stepping through multisyllabic speech plans. On the basis of previous reports, the model's components are hypothesized to be localized to specific cortical and subcortical structures, including the left inferior frontal sulcus, the medial premotor cortex, the basal ganglia, and the thalamus. The new model, called gradient order DIVA, thus fills a void in current speech research by providing formal mechanistic hypotheses about both phonological and phonetic processes that are grounded by neuroanatomy and physiology. This framework also generates predictions that can be tested in future neuroimaging and clinical case studies.

Prosodic planning: Local and distant effects of phrase length on pause duration.

Prosodic boundaries, as manifested in pause duration, are known to be influenced by structural properties of the phrases immediately preceding and following the boundary, such as their syntactic structure, prosodic structure, and phonological length. Little is known, however, about how phrases at a distance from a boundary, i.e., not immediately preceding or following it, may affect the durational characteristics of pausing at that boundary. An experiment is presented that investigates the effects on pause duration of prosodic phrases of different length, both immediately at the boundary and farther away from it. The goal is to (a) examine local and distant effects of prosodic phrase length on pause duration and (b) to examine incrementality in production of prosodic structure, i.e., to examine how far ahead speakers plan an utterance, and how prosodic structure affects the planning process. Subjects read 24 English sentences varying along the following parameters: (a) length in syllables (two or four syllables) of the intonational phrase immediately following a target pause and (b) length in syllables of the second, distant, intonational phrase following the pause (10 or 16 syllables long). The synchronous speech paradigm [F. Cummins (2002); E. Zvonik, F. Cummins (2002)] was used to minimize variability in production.

Speech planning during multiple-object naming: Effects of ageing

Two experiments were conducted with younger and older speakers. In Experiment 1, participants named single objects that were intact or visually degraded, while hearing distractor words that were phonologically related or unrelated to the object name. In both younger and older participants naming latencies were shorter for intact than for degraded objects and shorter when related than when unrelated distractors were presented. In Experiment 2, the single objects were replaced by object triplets, with the distractors being phonologically related to the first object's name. Naming latencies and gaze durations for the first object showed degradation and relatedness effects that were similar to those in single-object naming. Older participants were slower than younger participants when naming single objects and slower and less fluent on the second but not the first object when naming object triplets. The results of these experiments indicate that both younger and older speakers plan object names sequentially, but that older speakers use this planning strategy less efficiently.

Time pressure and phonological advance planning in spoken production

Current accounts of spoken production debate the extent to which speakers plan ahead. Here, we investigated whether the scope of phonological planning is influenced by changes in time pressure constraints. The first experiment used a picture–word interference task and showed that picture naming latencies were shorter when word distractors shared the final segments with the picture name. Experiment 2 used the same paradigm but with colored pictures to elicit determiner + adjective + noun phrases. Latencies were shorter when the distractor overlapped phonologically with the picture name. Finally, Experiment 3 demonstrated that in colored picture naming without distractors, latencies were shorter when the object noun began with the same phoneme as the color adjective. Crucially, in all experiments introduction of a response deadline accelerated latencies, but did not alter the relative magnitude of the priming effects. In sum, pressure to provide a swift response does not reduce the scope of phonological planning.

Planning at the Phonological Level during Sentence Production

In two picture-word interference experiments we examined whether phrase boundaries affected how far in advance speakers plan the sounds of words during sentence production. Participants produced sentences of varying lengths (short determiner + noun + verb or long determiner + adjective + noun + verb) while ignoring phonologically related and unrelated words to the verb of the sentence. Response times to begin producing both types of sentences were faster in the presence of a related versus unrelated distractor. The results suggest that the activation of phonological properties of words outside the first phrase and first and second phonological word affect onset of articulation during sentence production. The results are discussed in the light of previous evidence of phonological planning during multi-word production. Implications for the phonological facilitation effect in the picture-word interference paradigm are also discussed.

Observing the what and when of language production for different age groups by monitoring speakers’ eye movements

Research on adult age differences in language production has traditionally focused on either the production of single words or the properties of language samples. Older adults are more prone to word retrieval failures than are younger adults (e.g., Burke, MacKay, Worthley, & Wade, 1991). Older adults also tend to produce fewer ideas per utterance and fewer left-branching syntactic structures (e.g., Kemper, Greiner, Marquis, Prenovost, & Mitzner, 2001). The use of eye movement monitoring in the study of language production allows researchers to examine word production processes in the context of multiword utterances, bridging the gap between behavior in word production studies and spontaneous speech samples. This paper outlines one view of how speakers plan and produce utterances, summarizes the literature on age-related changes in production, presents an overview of the published research on speakers’ gaze during picture description, and recaps a study using eye movement monitoring to explore age-related changes in language production.

Using uh and um in spontaneous speaking

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.