Language acquisition

Previous research has demonstrated that sensitivity to unimodal nonnative speech
contrasts generally narrows during the first year. Although other work has demonstrated
a processing advantage for multimodal stimuli, research on infants' responsiveness to
nonnative contrasts so far has not examined whether concurrent auditory and visual
speech information can modulate perceptual narrowing. Thus, the current study
investigated the influence ofbimodally specified speech sounds on infants' sensitivity to
a nonnative phonemic contrast. Six-month-old and 10- to 12-month-old infants were
tested in a habituation/test procedure for discrimination of an audiovisual nonnative
speech contrast (Hindi /tal dental vs. /Tal retroflex stop). Findings showed that infants at
both ages exhibited evidence of discrimination following habituation to one of the speech
sounds. These findings suggest that the usually observed decline in responsiveness to
nonnative speech contrasts is limited to audibly specified contrasts and that concurrent
visual speech information enhances the discriminability of such contrasts.

From syllables to fluent speech, it is important for infants to quickly learn and decipher linguistic information. To do this, infants must not only use their auditory perception but also their visual perception to understand speech and language as a multisensory coherent event. Previous research by Lewkowicz and Hansen-Tift (2012) demonstrated that infants shift their allocation of visual attention from the eyes to the mouth of the speaker's face throughout development as they become interested in speech production. This project examined how infants, from 4-14-months of age, allocate their visual attention to increasingly complex speech tasks. In Experiment 1, infants were presented with upright and inverted faces vocalizing syllables and the results demonstrated that in response to the upright faces, 4-month-old infants attended to the eyes and 8- and 10-month-olds attended equally to the eyes and mouth. In response to the inverted face presentation, both the 4- and 10-month-olds attended equally to the eyes and mouth but the 8-month olds attended to the eyes. In Experiment 2, infants were presented with a phoneme matching task (Patterson & Werker, 1999, 2002, 2003) and the results demonstrated that the 4-month-old infants successfully matched the voice to the corresponding face, but that older infants did not. Measures of their selective attention to this task showed that the 4-month-old infants attended more to the eyes of the faces during the task, not attending to the redundant speech information at the mouth, but older infants attended equally to the eyes and mouth, although they did not match the voice to the face. Experiment 3 presented infants with a fluent speech matching task (Lewkowicz et al., 2015) which demonstrated that although the infants (12-14-months) did not systematically match the voice to the corresponding face, the infants attended more to the mouth region, which would have provided them with the neces sary redundant information. Overall, these studies demonstrate that there are developmental changes in how infants distribute their visual attention to faces as they learn about speech and that the complexity of the speech is a critical factor in how they allocate their visual attention.

The present research was designed to test whether 3-year-old-English-speaking children preferentially associate novel nouns with intrinsic motion rather than extrinsic motion, as predicted by the theory of Kersten (1998). Intrinsic motion refers to the ways the parts of an object move in relation to one another. In contrast, extrinsic motion refers to the motion of an object as a whole with respect to an external reference point (e.g. another object). In two separate experiments, we demonstrated that nouns are associated with intrinsic motion and verbs are associated with extrinsic motion. Specifically, children were able to detect differences between stimuli paired with novel nouns based on intrinsic motion and stimuli paired with novel verbs based on extrinsic motion. In other words, we shed light on the different motion cues children attend to when learning nouns and verbs. Thus, children utilize motion cues in addition to static characteristics when learning nouns and verbs. Therefore, distinct types of motion information play an important role in the learning of nouns and verbs.

Speech perception plays an important role in how infants begin to produce speech. This study aims to understand how changes in infant selective attention to various parts of talking faces guides their understanding of speech and subsequent production. In this study, we tracked infant (4-12 months of age) and adult gaze patterns to determine where on a face they attend, when hearing and seeing the face speak in either their native (English) or a non-native language (Spanish). We also tracked infant selective attention to moving-silent and silent-static faces, to determine if this would result in different patterns of attention. The findings suggest that there are two shifts in infant attention. The first shift occurs between four and eight months of age, with infants shifting their eyes to the mouth of the talking face. The second shift occurs around twelve months of age, when infants begin to return their gaze back to the eye region when hearing and seeing their native language, but continue to attend to the mouth region when hearing and seeing the non-native language. Overall, the results of this study suggest that changes in selective attention to talking faces guides the development of speech production and is dependent on early language experience.

The current study addressed several questions about the use of language intermingling in child-directed speech and its influence on children's English and Spanish language acquisition on children's language code-switching, Participants were 65 children (Mean age=30.93 months, SD=0.44, 28 boys and 37 girls) who had been exposed to English and Spanish from birth and for whom at least one parent was a native Spanish speaker.... Measures of the children's lexical, grammatical, receptive, and productive language development in English and in Spanish were collected concurrently.... Consistent with sociolinguistic theories that propose that language separation is necessary for heritage language maintenance, children who were exposed to more language intermingling were more English-dominant. Both sensitivity to the language context and children's language dominance were related to children's production of mixed utterances. Children code-switched more when speaking in their less proficient language and when in the context of minority language use.

This study investigated the effects of family composition and properties of children's dual language exposure on bilingual first language acquisition. Mothers of 29 toddlers (13 boys and 16 girls, M age = 25.66 months, SD = .44) kept a language diary, providing measures of the amount, the contexts, and the persons with whom the children experienced English and Spanish. Measures of the children's vocabulary balance were obtained from English and Spanish language inventories. Results showed that only children with two native Spanish-speaking parents had larger Spanish than English vocabularies and experienced more hours of Spanish-only exposure and Spanish-only conversational contexts. Analysis of covariance demonstrated that the effect of family composition on vocabulary balance was completely mediated by the balance of English and Spanish in the children's language exposure. There was no evidence of a unique effect of experiencing Spanish-only conversational contexts or partners on children's acquisition of Spanish.

This experiment tested 3 to 5-year-old children's (n=18) abilities to learn a novel verb in the context of one or two novel objects. We showed the children claymation videos of novel creatures performing two novel actions. They were then tested on whether they could correctly identify the action that a creature was performing in the form of a 'yes' or 'no' response. Children in the blocked condition, who learned the verbs in the context of one creature, responded correctly more often (p=.01) than children in the grouped condition, who learned the verbs in the context of two creatures. Results were similar when tested again one week later. These findings suggest that when teaching young children verbs, it may be more effective to first teach in the context of one object so that the children have a more confident understanding of the verb meaning.