Early language development is characterized by predictable changes in the words children produce and the complexity of their utterances. In infants these changes could reflect increasing linguistic expertise or cognitive maturation and development. To disentangle these factors, we compared the acquisition of English in internationally-adopted preschoolers and internationallyadopted infants. Parental reports and speech samples were collected for one year. Both groups showed the qualitative shifts that characterize first-language acquisition. Initially, they produced single-word utterances consisting mostly of nouns and social words. The appearance of verbs, adjectives and multiword utterances was predicted by vocabulary size in both groups. Preschoolers did learn some words at an earlier stage than infants, specifically words referring to the past or future and adjectives describing behavior and internal states. These findings suggest that cognitive development plays little role in the shift from referential terms to predicates but may constrain children’s ability to learn some abstract words.

These studies explore the effects of cognitive maturation on language development by examining the acquisition of English in internationally-adopted preschoolers. Parental reports (CDI) were collected from 48 preschoolers, within the first year after they were adopted from China or Eastern Europe. Children who were adopted at two or three years of age showed the same developmental patterns in language production as monolingual infants (matched for vocabulary size). Early on, their vocabularies were dominated by nouns and social words and the proportion of predicates and closed-class words increased with age. Thus shifts in lexical composition appear in older learners and are unlikely to reflect the development of new conceptual resources. Children who were adopted at four or five deviated from this pattern, acquiring fewer nouns and more predicates in the early stages of acquisition. Effects of the child’s birth language on the acquisition of English were limited to the older preschoolers, suggesting that they employ different strategies in word learning. In both groups, grammatical development and lexical development were synchronized in precisely the same way that they are in infancy, raising the possibility that word production and grammatical production are causally connected.

Early language development is characterized by predictable changes in the words children produce and the complexity of their utterances. In infants these changes could reflect increasing linguistic expertise or cognitive maturation and development. To disentangle these factors, we compared the acquisition of English in internationallyadopted preschoolers and internationally-adopted infants. Parental reports and speech samples were collected for one year. Both groups showed the qualitative shifts that characterize first-language acquisition. Initially, they produced single-word utterances consisting mostly of nouns and social words. The appearance of verbs, adjectives and multi-word utterances was predicted by vocabulary size in both groups. Preschoolers did learn some words at an earlier stage than infants, specifically words referring to the past or future and adjectives describing behavior and internal states. These findings suggest that cognitive development plays little role in the shift from referential terms to predicates but may constrain children’s ability to learn some abstract words.

There is ample evidence for a connection between linguistic abilities and performance in theory of mind tasks (ToM), however there is considerable dispute about precisely how these domains are linked. Disentangling the causal relations between domains in typically developing children is tricky because many skills are developing in synchrony. If ToM performance depends upon children’s current linguistic abilities, then the relation should be present even when language acquisition is delayed. We explored these issues in a group of late English learners, 45 internationally adopted children who came to the US at 2.5 years or older, and a control group of language matched preschoolers who were learning English as a first language. The children were tested on general English language abilities, sentence complement comprehension, English vocabulary and ToM. The two groups performed similarly on standard verbal ToM tasks, even though the adopted group was on average nearly 3 years older. However, the adopted children outperformed the controls in ToM tasks with reduced linguistic demands. General language skills predicted ToM ability in both groups and complement comprehension did not account for any additional variance. The data suggests that executive functioning along with general language skills may be the critical components in ToM success. 3

Broadcast video and virtual environments are just two of the growing number of domains in which language is embedded in multiple modalities of rich non-linguistic information. Applications for such multimodal domains are often based on traditional natural language processing techniques that ignore the connection between words and the non-linguistic context in which they are used. This thesis describes a methodology for representing these connections in models which ground the meaning of words in representations of events. Incorporating these grounded language models with text-based techniques significantly improves the performance of three multimodal applications: natural language understanding in videogames, sports video search and automatic speech recognition. Two approaches to representing the structure of events are presented and used to model the meaning of words. In the domain of virtual game worlds, a hand-designed hierarchical behavior grammar is used to explicitly represent all the various actions that an agent can take in a virtual world. This grammar is used to interpret events by parsing sequences of observed actions in order to generate hierarchical event structures. In the noisier and more open-ended domain of

Many theories of early word learning begin with the uncertainty inherent to learning a word from its co-occurrence with a visual scene. However, the relevant visual scene for infant word learning is neither from the adult theorist’s view nor the mature partner’s view, but is rather from the learner’s personal view. Here we show that when 18-month old infants interacted with objects in play with their parents, they created moments in which a single object was visually dominant. If parents named the object during these moments of bottom-up selectivity, later forced-choice tests showed that infants learned the name, but did not when naming occurred during a less visually selective moment. The momentary visual input for parents and toddlers was captured via head cameras placed low on each participant’s forehead as parents played with and named objects for their infant. Frame-by-frame analyses of the head camera images at and around naming moments were conducted to determine the visual properties at input that were associated with learning. The analyses indicated that learning occurred when bottom-up visual information was clean and uncluttered. The sensory-motor behaviors of infants and parents were also analyzed to determine how their actions on the objects may have created these optimal visual moments for learning. The results are discussed with respect to early word learning, embodied attention, and the social role of parents in early word learning. 2 Infants learn their first words through the co-occurrence of a heard word and a visual