Speech disfluencies can guide the ways in which listeners interpret spoken language. Here, we examined whether three-year-olds, five-year-olds, and adults use filled pauses to anticipate that a speaker is likely to refer to a novel object. Across three experiments, participants were presented with pairs of novel and familiar objects and heard a speaker refer to one of the objects using a fluent ("Look at the ball/lep!") or disfluent ("Look at thee uh ball/lep!") expression. The salience of the speaker's unfamiliarity with the novel referents, and the way in which the speaker referred to the novel referents (i.e., a noun vs. a description) varied across experiments. Three- and five-year-olds successfully identified familiar and novel targets, but only adults' looking patterns reflected increased looks to novel objects in the presence of a disfluency. Together, these findings demonstrate that adults, but not young children, use filled pauses to anticipate reference to novel objects.

An eye-tracking methodology was used to examine whether children flexibly engage two voice-based cues, talker identity and disfluency, during language processing. Across two experiments, 5-year-olds (N = 58) were introduced to two characters with distinct color preferences. These characters then used fluent or disfluent instructions to refer to an object in a display containing items bearing either talker-preferred or talker-dispreferred colors. As the utterance began to unfold, the 5-year-olds anticipated that talkers would refer to talker-preferred objects. When children then encountered a disfluency in the unfolding description, they reduced their expectation that a talker was about to refer to a preferred object. The talker preference-related predictions, but not the disfluency-related predictions, were attenuated during the second half of the experiment as evidence accrued that talkers referred to dispreferred objects with equal frequency. In Experiment 2, the equivocal nature of talkers' referencing was made more apparent by removing neutral filler trials, where objects' colors were not associated with talker preferences. In this case, children ceased making all talker-related predictions during the latter half of the experiment. Taken together, the results provide insights into children's use of talker-specific cues and demonstrate that flexible and adaptive forms of reasoning account for the ways in which children draw on paralinguistic information during real-time processing.

An eye-tracking methodology was used to explore adults’ and children’s use of two utterance-based cues to overcome referential uncertainty in real time. Participants were first introduced to two characters with distinct color preferences. These characters then produced fluent (“Look! Look at the blicket.”) or disfluent (“Look! Look at thee, uh, blicket.”) instructions referring to novel objects in a display containing both talker-preferred and talker-dispreferred colored items. Adults (Expt 1, n = 24) directed a greater proportion of looks to talker-preferred objects during the initial portion of the utterance (“Look! Look at…”), reflecting the use of indexical cues for talker identity. However, they immediately reduced consideration of an object bearing the talker’s preferred color when the talker was disfluent, suggesting they infer disfluency would be more likely as a talker describes dispreferred objects. Like adults, 5-year-olds (Expt 2, n = 27) directed more attention to talker-preferred objects during the initial portion of the utterance. Children’s initial predictions, however, were not modulated when disfluency was encountered. Together, these results demonstrate that adults, but not 5-year-olds, can act on information from two talker-produced cues within an utterance, talker preference, and speech disfluencies, to establish reference.

Brains can perceive or recognize a face even though we are subjectively unaware of the existence of that face. However, the exact neural correlates of such covert face processing remain unknown. Here, we compared the fMRI activities between a prosopagnosic patient and normal controls when they saw famous and unfamiliar faces. When compared with objects, the patient showed greater activation to famous faces in the fusiform face area (FFA) though he could not overtly recognize those faces. In contrast, the controls showed greater activation to both famous and unfamiliar faces in the FFA. Compared with unfamiliar faces, famous faces activated the controls', but not the patient's lateral prefrontal cortex (LPFC) known to be involved in familiar face recognition. In contrast, the patient showed greater activation in the bilateral medial frontal gyrus (MeFG). Functional connectivity analyses revealed that the patient's right middle fusiform gyrus (FG) showed enhanced connectivity to the MeFG, whereas the controls' middle FG showed enhanced connectivity to the LPFC. These findings suggest that the FFA may be involved in both covert and overt face recognition. The patient's impairment in overt face recognition may be due to the absence of the coupling between the right FG and the LPFC.

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