Collaboration under uncertainty in unscripted conversations: The role of hedges.

The present study examined the role of hedges in a referential communication task. Pairs of participants received an identical set of cards, each card displaying a geometric configuration (a "tangram"). One participant, the director, instructed their partner, the matcher, to reproduce a series of predetermined tangram sequences using their own cards. Directors sometimes included a hedge in their description of a tangram (e.g., "looks kinda like an eagle"), and more so the first time than on subsequent mentions. The present study tested the hypothesis that, by revealing their uncertainty regarding the adequacy of their description in conveying the intended meaning, directors signal a possible difficulty in establishing reference. This in turn prompts their addressee to display, rather than merely assert, their understanding (by presenting a description for the tangram the matcher believes the director is referring to, for the director to evaluate). Analyses of matchers' responses to descriptions that directors had hedged or not confirmed the hypothesis. This finding supports the view that conversational partners work together to reach the mutual belief that they have coordinated what the speaker means and what their addressee takes them to mean. Conversational partners expend more joint effort when they deem the risk of misunderstanding to be high than when it is perceived to be low. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Imitation of coarticulatory vowel nasality across words and time.

We investigated phonetic imitation of coarticulatory vowel nasality using an adapted shadowing paradigm in which participants produced a printed word (target) after hearing a different word (prime). Two versions of primes with nasal codas were used: primes with a natural degree of vowel nasality and hypernasalized primes. The version of the prime participants heard varied, whether consistent with their past experience with nasality from the talker or inconsistent, and the duration of delay between prime and target. People spontaneously modify coarticulatory nasality to resemble that demonstrated in the prime they were exposed to. Furthermore, this imitation also reflects the degree of nasality demonstrated by overall experience with the speaker's vowels. The influence of past experience on imitation increases with increased delay between prime and target. Imitation of another speaker appears to involve tracking general articulatory properties about the speaker, and not solely what was specific to the most recent experience.

Differences in coda voicing trigger changes in gestural timing: A test case from the American English diphthong /aɪ/.

We investigate the hypothesis that duration and spectral differences in vowels before voiceless versus voiced codas originate from a single source, namely the reorganization of articulatory gestures relative to one another in time. As a test case, we examine the American English diphthong /aɪ/, in which the acoustic manifestations of the nucleus /a/ and offglide /ɪ/ gestures are relatively easy to identify, and we use the ratio of nucleus-to-offglide duration as an index of the temporal distance between these gestures. Experiment 1 demonstrates that, in production, the ratio is smaller before voiceless codas than before voiced codas; this effect is consistent across speakers as well as changes in speech rate and phrasal position. Experiment 2 demonstrates that, in perception, diphthongs with contextually incongruent ratios delay listeners' identification of target words containing voiceless codas, even when the other durational and spectral correlates of voicing remain intact. This, we argue, is evidence that listeners are sensitive to the gestural origins of voicing differences. Both sets of results support the idea that the voicing contrast triggers changes in timing: gestures are close to one another in time before voiceless codas, but separated from one another before voiced codas.

Prosody and language comprehension.

This review provides a summary of the most recent advances on the study of how prosody is used during language comprehension. Prosody is characterized as an abstract structure composed of discrete tonal elements aligned with the segmental composition of the sentence organized in constituents of increasing size, and this structure is influenced by the phonological, syntactic, and informational structures of the sentence. Here, we discuss evidence that listeners are affected by prosody when establishing those linguistic structures. Prosody has been shown to influence the segmentation of the utterance into syllables and words, and, in some cases, whether a syllable or word is judged to be present or not. The literature on how prosody informs the structural relationship between words and phrases is also discussed, contrasting views that assume a direct (albeit probabilistic) link between syntax and prosody with those that posit a complex interface between syntax and prosodic structure. Finally, the role of prosody in conveying important aspects pertaining to the sentence's information structure (i.e., which parts of the sentence's meaning are highlighted and brought forward to the discourse, which ones are presupposed and left in the background, which attitudes are being conveyed about the concepts or propositional content) has long been recognized. Current research focuses on which prosodic elements contribute to marking the dimensions (or semantic primitives) of the information structure.

Context-conditioned generalization in adaptation to distorted speech.

People were trained to decode noise-vocoded speech by hearing monosyllabic stimuli in distorted and unaltered forms. When later presented with different stimuli, listeners were able to successfully generalize their experience. However, generalization was modulated by the degree to which testing stimuli resembled training stimuli: Testing stimuli's consonants were easier to recognize when they had occurred in the same position at training, or flanked by the same vowel, than when they did not. Furthermore, greater generalization occurred when listeners had been trained on existing words than on nonsense strings. We propose that the process by which adult listeners learn to interpret distorted speech is akin to building phonological categories in one's native language, a process where categories and structure emerge from the words in the ambient language without completely abstracting from them.

The effect of the temporal structure of spoken words on paired-associate learning.

In a series of experiments, participants learned to associate black-and-white shapes with nonsense spoken labels (e.g., "joop"). When tested on their recognition memory, participants falsely recognized as correct a shape paired with a label that began with the same sounds as the shape's original label (onset-overlapping lure; e.g., joob) more often than a shape paired with a label that overlapped with the original label at offset (offset-overlapping lure; e.g., choop). Furthermore, the false-alarm rate was modulated by the phonetic distance between the sounds that distinguished the original label and the lures. Greater false-alarm rates to onset-overlapping labels were not predicted by explicit similarity ratings or by consonant identification and were not dependent upon label familiarity. The asymmetry at erroneously recognizing onset- versus offset-overlapping lures remained unchanged as the presentation of the shape at test was delayed in time, suggesting that response anticipation based on the first sounds of the spoken label did not contribute much to the false recognition of onset-overlapping lures. Thus, learning 2 words whose names differ in their last sounds appears to pose greater difficulty than learning 2 words whose names differ in their first sounds because, we argue, people are biased to give more importance to the early sounds of a name than to its last sounds when learning a novel label-referent association. (PsycINFO Database Record (c) 2009 APA, all rights reserved).

Talker adaptation in speech perception: adjusting the signal or the representations?

Past research has established that listeners can accommodate a wide range of talkers in understanding language. How this adjustment operates, however, is a matter of debate. Here, listeners were exposed to spoken words from a speaker of an American English dialect in which the vowel /ae/ is raised before /g/, but not before /k/. Results from two experiments showed that listeners' identification of /k/-final words like back (which are unaffected by the dialect) was facilitated by prior exposure to their dialect-affected /g/-final counterparts, e.g., bag. This facilitation occurred because the competition between interpretations, e.g., bag or back, while hearing the initial portion of the input [bae], was mitigated by the reduced probability for the input to correspond to bag as produced by this talker. Thus, adaptation to an accent is not just a matter of adjusting the speech signal as it is being heard; adaptation involves dynamic adjustment of the representations stored in the lexicon, according to the characteristics of the speaker or the context.

The temporal dynamics of ambiguity resolution: Evidence from spoken-word recognition.

Two experiments examined the dynamics of lexical activation in spoken-word recognition. In both, the key materials were pairs of onset-matched picturable nouns varying in frequency. Pictures associated with these words, plus two distractor pictures were displayed. A gating task, in which participants identified the picture associated with gradually lengthening fragments of spoken words, examined the availability of discriminating cues in the speech waveforms for these pairs. There was a clear frequency bias in participants' responses to short, ambiguous fragments, followed by a temporal window in which discriminating information gradually became available. A visual-world experiment examined speech contingent eye-movements. Fixation analyses suggested that frequency influences lexical competition well beyond the point in the speech signal at which the spoken word has been fully discriminated from its competitor (as identified using gating). Taken together, these data support models in which the processing dynamics of lexical activation are a limiting factor on recognition speed, over and above the temporal unfolding of the speech signal.

Effects of prosodically modulated sub-phonetic variation on lexical competition.

Eye movements were monitored as participants followed spoken instructions to manipulate one of four objects pictured on a computer screen. Target words occurred in utterance-medial (e.g., Put the cap next to the square) or utterance-final position (e.g., Now click on the cap). Displays consisted of the target picture (e.g., a cap), a monosyllabic competitor picture (e.g., a cat), a polysyllabic competitor picture (e.g., a captain) and a distractor (e.g., a beaker). The relative proportion of fixations to the two types of competitor pictures changed as a function of the position of the target word in the utterance, demonstrating that lexical competition is modulated by prosodically conditioned phonetic variation.

Looking at the rope when looking for the snake: conceptually mediated eye movements during spoken-word recognition.

Participants' eye movements to four objects displayed on a computer screen were monitored as the participants clicked on the object named in a spoken instruction. The display contained pictures of the referent (e.g., a snake), a competitor that shared features with the visual representation associated with the referent's concept (e.g., a rope), and two distractor objects (e.g., a couch and an umbrella). As the first sounds of the referent's name were heard, the participants were more likely to fixate the visual competitor than to fixate either of the distractor objects. Moreover, this effect was not modulated by the visual similarity between the referent and competitor pictures, independently estimated in a visual similarity rating task. Because the name of the visual competitor did not overlap with the phonetic input, eye movements reflected word-object matching at the level of lexically activated perceptual features and not merely at the level of preactivated sound forms.

Continuous mapping from sound to meaning in spoken-language comprehension: immediate effects of verb-based thematic constraints.

The authors used 2 "visual-world" eye-tracking experiments to examine lexical access using Dutch constructions in which the verb did or did not place semantic constraints on its subsequent subject noun phrase. In Experiment 1, fixations to the picture of a cohort competitor (overlapping with the onset of the referent's name, the subject) did not differ from fixations to a distractor in the constraining-verb condition. In Experiment 2, cross-splicing introduced phonetic information that temporarily biased the input toward the cohort competitor. Fixations to the cohort competitor temporarily increased in both the neutral and constraining conditions. These results favor models in which mapping from the input onto meaning is continuous over models in which contextual effects follow access of an initial form-based competitor set.

The role of prosodic boundaries in the resolution of lexical embedding in speech comprehension.

Participants' eye movements were monitored as they heard sentences and saw four pictured objects on a computer screen. Participants were instructed to click on the object mentioned in the sentence. There were more transitory fixations to pictures representing monosyllabic words (e.g. ham) when the first syllable of the target word (e.g. hamster) had been replaced by a recording of the monosyllabic word than when it came from a different recording of the target word. This demonstrates that a phonemically identical sequence can contain cues that modulate its lexical interpretation. This effect was governed by the duration of the sequence, rather than by its origin (i.e. which type of word it came from). The longer the sequence, the more monosyllabic-word interpretations it generated. We argue that cues to lexical-embedding disambiguation, such as segmental lengthening, result from the realization of a prosodic boundary that often but not always follows monosyllabic words, and that lexical candidates whose word boundaries are aligned with prosodic boundaries are favored in the word-recognition process.

The time course of spoken word learning and recognition: studies with artificial lexicons.

The time course of spoken word recognition depends largely on the frequencies of a word and its competitors, or neighbors (similar-sounding words). However, variability in natural lexicons makes systematic analysis of frequency and neighbor similarity difficult. Artificial lexicons were used to achieve precise control over word frequency and phonological similarity. Eye tracking provided time course measures of lexical activation and competition (during spoken instructions to perform visually guided tasks) both during and after word learning, as a function of word frequency, neighbor type, and neighbor frequency. Apparent shifts from holistic to incremental competitor effects were observed in adults and neural network simulations, suggesting such shifts reflect general properties of learning rather than changes in the nature of lexical representations.