Katherine S. White

Prosody guides the rapid mapping of auditory word forms onto visual objects in 6-mo-old infants

Human infants are predisposed to rapidly acquire their native language. The nature of these predispositions is poorly understood, but is crucial to our understanding of how infants unpack their speech input to recover the fundamental word-like units, assign them referential roles, and acquire the rules that govern their organization. Previous researchers have demonstrated the role of general distributional computations in prelinguistic infants’ parsing of continuous speech. We extend these findings to more naturalistic conditions, and find that 6-mo-old infants can simultaneously segment a nonce auditory word form from prosodically organized continuous speech and associate it to a visual referent. Crucially, however, this mapping occurs only when the word form is aligned with a prosodic phrase boundary. Our findings suggest that infants are predisposed very early in life to hypothesize that words are aligned with prosodic phrase boundaries, thus facilitating the word learning process. Further, and somewhat paradoxically, we observed successful learning in a more complex context than previously studied, suggesting that learning is enhanced when the language input is well matched to the learners expectations.

Word-level information influences phonetic learning in adults and infants

Infants begin to segment words from fluent speech during the same time period that they learn phonetic categories. Segmented words can provide a potentially useful cue for phonetic learning, yet accounts of phonetic category acquisition typically ignore the contexts in which sounds appear. We present two experiments to show that, contrary to the assumption that phonetic learning occurs in isolation, learners are sensitive to the words in which sounds appear and can use this information to constrain their interpretation of phonetic variability. Experiment 1 shows that adults use word-level information in a phonetic category learning task, assigning acoustically similar vowels to different categories more often when those sounds consistently appear in different words. Experiment 2 demonstrates that 8-month-old infants similarly pay attention to word-level information and that this information affects how they treat phonetic contrasts. These findings suggest that phonetic category learning is a rich, interactive process that takes advantage of many different types of cues that are present in the input.

SMART-T: A system for novel fully automated anticipatory eye-tracking paradigms

Anticipatory eye movements (AEMs) are a natural and implicit measure of cognitive processing and have been successfully used to document such important cognitive capacities as learning, categorization, and generalization, especially in infancy (McMurray & Aslin, Infancy, 6, 203–229, 2004). Here, we describe an improved AEM paradigm to automatically assess online learning on a trial-by-trial basis, by analyzing eye gaze data in each intertrial interval of a training phase. Different measures of learning can be evaluated simultaneously. We describe the implementation of a system for designing and running a variety of such AEM paradigms. Additionally, this system is capable of a wider variety of gaze-contingent paradigms, as well as implementations of standard noncontingent paradigms. Our system, Smart-T (System for Monitoring Anticipations in Real Time with the Tobii), is a set of MATLAB scripts with a graphical front end, written using the Psychophysics Toolbox. The system gathers eye gaze data using the commercially available Tobii eye-trackers via a MATLAB module, Talk2Tobii. We report a pilot study showing that Smart-T can detect 6-month-old infants’ learning of simple predictive patterns involving the disappearance and reappearance of multimodal stimuli.

Where are you from? Preschoolers infer background from accent

For adults, accent is an obvious indicator of a speakers geographical background. The current study investigated whether preschoolers are sensitive to the relationship between background and accent. Experiment 1 shows that 3- to 5-year-olds believe that two speakers who share the same accent live in the same place but do not share the same personal preferences. Experiment 2 demonstrates that 4- and 5-year-olds believe that two speakers with the same accent share cultural norms associated with a particular place, but that two speakers with different accents have different cultural norms. As in Experiment 1, children did not think that personal preferences were related to accent. These findings show early awareness of the relationship between accent and geographical background.

He Says Potato, She Says Potahto: Young Infants Track Talker-Specific Accents.

ABSTRACT One of the most fundamental aspects of learning a language is determining the mappings between words and referents. An often-overlooked complication is that infants interact with multiple individuals who may not produce words in the same way. In the present study, we explored whether 10- to 12-month-olds can use talker-specific knowledge to infer the intended referents of novel labels. During exposure, infants heard two talkers whose front vowels differed; one talker trained them on a word-referent mapping. At test, infants saw the trained object and a novel object; they heard a single novel label from both talkers. When the label had a front vowel (Experiment 1), infants responded differently as a function of talker, but when it had a back vowel (Experiment 2), they did not, mapping the novel label to the novel object for both talkers. These results suggest that infants can track the phonetic properties of two simultaneously presented talkers and use information about each talker’s previous productions to guide their referential interpretations.

Listeners learn phonotactic patterns conditioned on suprasegmental cues

Language learners are sensitive to phonotactic patterns from an early age, and can acquire both simple and 2nd-order positional restrictions contingent on segment identity (e.g., /f/ is an onset with /æ/but a coda with /ɪ/). The present study explored the learning of phonototactic patterns conditioned on a suprasegmental cue: lexical stress. Adults first heard non-words in which trochaic and iambic items had different consonant restrictions. In Experiment 1, participants trained with phonotactic patterns involving natural classes of consonants later falsely recognized novel items that were consistent with the training patterns (legal items), demonstrating that they had learned the stress-conditioned phonotactic patterns. However, this was only true for iambic items. In Experiment 2, participants completed a forced-choice test between novel legal and novel illegal items and were again successful only for the iambic items. Experiment 3 demonstrated learning for trochaic items when they were presented alone. Finally, in Experiment 4, in which the training phase was lengthened, participants successfully learned both sets of phonotactic patterns. These experiments provide evidence that learners consider more global phonological properties in the computation of phonotactic patterns, and that learners can acquire multiple sets of patterns simultaneously, even contradictory ones.

Selective influences of nonphonemic variability on early word recognition

Experience with words is necessarily episodic: Each encounter with a word is distinct from previous encounters of that word due to contextual or indexical factors. Nevertheless, we must recognize phonetically distinct instances of a word as lexically equivalent. The normalization problem is particularly challenging for prelexical infants who may not know which acoustic dimensions are phonemic, evidenced by findings that young infants only recognize words when words are perceptually similar across encounters (e.g., spoken by talkers of the same gender). By contrast, older infants are able to recognize dissimilar tokens of words, raising the question of why young infants consider nonphonemic acoustic detail in word recognition. In a series of studies investigating conditions that disrupt early word recognition, it was found that young infants treated as deterministic acoustic detail that may be phonemic in any given language (e.g., vowel length, pitch). Conversely, they effortlessly disregarded details that...

Distributional and statistical bases of allophonic groupings

Segments of a given language do not all have equal status: some are phonetic variants of others. These variants occur only in certain contexts. In addition to occurring in more restricted contexts, however, variant allophones typically occur with lesser frequency. Which (if either) of these asymmetries is important for infants learning of allophonic groupings? Infants were exposed to artificial languages with allophones. Either stops or fricatives were intervocalicly voiced; these voiced segments did not otherwise occur. Infants were then tested on preference for passages like ‘‘rot pazo na bazo rot pazo na bazo’’ or ‘‘na zine rot sine na zine rot sine...’’ All items were grammatical for both groups. For the stop allophone group, /pazo/ and /bazo/ should be one word, whereas /zine/ and /sine/ should be two words; vice versa for the fricative allophone group. In previous work using a similar technique, infants listened longer to passages containing what was perceived as two variants. Across a series of exp...