To explore how online speech processing efficiency relates to vocabulary growth in the 2nd year, the authors longitudinally observed 59 English-learning children at 15, 18, 21, and 25 months as they looked at pictures while listening to speech naming one of the pictures. The time course of eye movements in response to speech revealed significant increases in the efficiency of comprehension over this period. Further, speed and accuracy in spoken word recognition at 25 months were correlated with measures of lexical and grammatical development from 12 to 25 months. Analyses of growth curves showed that children who were faster and more accurate in online comprehension at 25 months were those who showed faster and more accelerated growth in expressive vocabulary across the 2nd year. Keywordsinfant language comprehension; infant speech processing; lexical development; eye-tracking; online measures Children in the early stages of learning a language are often credited with "acquiring" new vocabulary, as if words come one by one into the child's possession. When we speak of acquiring something like a piano or a piece of property, the emphasis is on ownership, an odd way to characterize the complex and incremental processes involved in word learning. However, we also speak of acquiring skills, such as playing the piano, in which the emphasis is on gradual mastery rather than possession. It is increasingly evident that learning to recognize, understand, and speak a new word appropriately is a gradual process. Not only do infants respond meaningfully to more and more words over the 2nd year, they also respond with increasing speed and efficiency to each of the words they are learning. That is, rather than "acquiring" a new word in an all-or-none fashion, they get better at recognizing and interpreting the same word in more diverse and challenging contexts.Because comprehension is a mental activity not easily observable in infants' spontaneous behavior, the gradual emergence of understanding has been difficult to study with precision. However, with the refinement of procedures that track listeners' eye movements as they scan a visual array in response to speech, a technique used widely in research with adults (Tanenhaus, Magnusen, Dahan, & Chambers, 2000), it is now possible to monitor the time course of spoken language understanding in very young children. Using a looking-whilelistening procedure with infants from 15 to 24 months of age, Fernald, Pinto, Swingley, Weinberg, and McRoberts (1998) NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript understanding increase dramatically over the 2nd year. In that study, infants looked at pictures of objects while listening to speech naming one of the objects with a familiar word. Whereas 15-month-olds responded inconsistently and shifted their gaze to the correct picture only after the end of the target word, 24-month-olds were faster and more reliable in their responses, initiating a shift in gaze midway through the target word based on partial p...

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Word associations have been used widely in psychology, but the validity of their application strongly depends on the number of cues included in the study and the extent to which they probe all associations known by an individual. In this work, we address both issues by introducing a new English word association dataset. We describe the collection of word associations for over 12,000 cue words, currently the largest such English-language resource in the world. Our procedure allowed subjects to provide multiple responses for each cue, which permits us to measure weak associations. We evaluate the utility of the dataset in several different contexts, including lexical decision and semantic categorization. We also show that measures based on a mechanism of spreading activation derived from this new resource are highly predictive of direct judgments of similarity. Finally, a comparison with existing English word association sets further highlights systematic improvements provided through these new norms.

Inductive learning is impossible without overhypotheses, or constraints on the hypotheses considered by the learner. Some of these overhypotheses must be innate, but we suggest that hierarchical Bayesian models help explain how the rest can be acquired. To illustrate this claim, we develop models that acquire two kinds of overhypotheses -overhypotheses about feature variability (e.g. the shape bias in word learning) and overhypotheses about the grouping of categories into ontological kinds like objects and substances. Learning overhypotheses 3Learning overhypotheses with hierarchical Bayesian models Compared to our best formal models, children are remarkable for learning so much from so little. A single labelled example is enough for children to learn the meanings of some words (Carey & Bartlett, 1978), and children develop grammatical constructions that are rarely found in the sentences that they hear (Chomsky, 1980). These inductive leaps appear even more impressive when we consider the many interpretations of the data that are logically possible but apparently never entertained by children (Goodman, 1955;Quine, 1960).Learning is impossible without constraints of some sort, but the apparent ease of children's learning may rely on relatively strong inductive constraints. Researchers have suggested, for example, that the M-constraint (Keil, 1979) and the shape bias (Heibeck & Markman, 1987) help explain concept learning, that universal grammar guides the acquisition of linguistic knowledge (Chomsky, 1980), and that constraints on the properties of physical objects (Spelke, 1990) support inferences about visual scenes.Constraints like these may be called theories or schemata, but we will borrow a term of Goodman's and refer to them as overhypotheses. 1 Although overhypotheses play a prominent role in nativist approaches to development (Keil, 1979;Chomsky, 1980;Spelke, 1990), some overhypotheses are probably learned (Goldstone & Johansen, 2003). One such overhypothesis is the shape bias -the expectation that all of the objects in a given category tend to have the same shape, even if they differ along other dimensions, such as color and texture. Smith, Jones, Landau, Gershkoff-Stowe, and Samuelson (2002) provide strong evidence that the shape bias is learned by showing that laboratory training allows children to demonstrate this bias at an age before it normally emerges. Other overhypotheses that appear to be learned include constraints on the rhythmic pattern of a child's native language (Jusczyk, 2003), Learning overhypotheses 4 and constraints on the kinds of feature correlations that are worth tracking when learning about artifacts or other objects (Madole & Cohen, 1995).The acquisition of overhypotheses raises some difficult challenges for formal models.It is difficult at first to understand how something as abstract as an overhypothesis might be learned, and the threat of an infinite regress must also be confronted -what are the inductive constraints that allow inductive constraints to be learned? ...