A decade of research suggests that infants readily detect patterns in their environment, but it is unclear how such learning changes with experience. We tested how prior experience influences sensitivity to statistical regularities in an artificial language. Although 12-month-old infants learn adjacent relationships between word categories, they do not track nonadjacent relationships until 15 months. We asked whether 12-month-old infants could generalize experience with adjacent dependencies to nonadjacent ones. Infants were familiarized to an artificial language either containing or lacking adjacent dependencies between word categories and were subsequently habituated to novel nonadjacent dependencies. Prior experience with adjacent dependencies resulted in enhanced learning of the nonadjacent dependencies. Female infants showed better discrimination than males did, which is consistent with earlier reported sex differences in verbal memory capacity. The findings suggest that prior experience can bootstrap infants' learning of difficult language structure and that learning mechanisms are powerfully affected by experience.Statistical information, such as the frequency of different events and the likelihood of their co-occurrence with other events, provides us with critical knowledge about our environment. For example, facial features are likely to co-occur (e.g., mouths co-occur with two eyes and a nose). Likewise, the occurrence of the word a or the suggests that a noun like cat or duck is likely to follow. Sensitivity to statistical information emerges early in development, with infants detecting regularities in visual input by 2 months of age (Kirkham, Slemmer, & Johnson, 2002) and in aurally presented stimuli by 7 months (Saffran, Aslin, & Newport, 1996;. Research over the last decade suggests that statistical learning plays a critical role in language acquisition by supporting segmentation of words from fluent speech (Saffran et al., 1996), acquisition of word-order patterns (Gómez & Gerken, 1999), and syntactic categories and their co-occurrence privileges (Gerken, Wilson, & Lewis, 2005;Gómez & LaKusta, 2004).One important question researchers would like to answer is how statistical learning is affected by experience, and they have begun to address this question in the domains of word segmentation and vocabulary development. For example, experience with phonological properties helps infants segment words from fluent speech Thiessen & Saffran, 2007), and successful word segmentation in turn facilitates learning cooccurrence relationships between words (Saffran & Wilson, 2003). Likewise, experience with associations between individual objects and labels can attune infants to higher order correspondences between words and their referents (e.g., object labels tend to refer to things In our study, we asked how prior experience influences the acquisition of complex syntactic patterns. For example, sensitivity to nonadjacent relationships between words is necessary for learning the hierarchical structure o...

Psychological scientists have become increasingly concerned with issues related to methodology and replicability, and infancy researchers in particular face specific challenges related to replicability: For example, high-powered studies are difficult to conduct, testing conditions vary across labs, and different labs have access to different infant populations. Addressing these concerns, we report on a large-scale, multisite study aimed at (a) assessing the overall replicability of a single theoretically important phenomenon and (b) examining methodological, cultural, and developmental moderators. We focus on infants’ preference for infant-directed speech (IDS) over adult-directed speech (ADS). Stimuli of mothers speaking to their infants and to an adult in North American English were created using seminaturalistic laboratory-based audio recordings. Infants’ relative preference for IDS and ADS was assessed across 67 laboratories in North America, Europe, Australia, and Asia using the three common methods for measuring infants’ discrimination (head-turn preference, central fixation, and eye tracking). The overall meta-analytic effect size (Cohen’s d) was 0.35, 95% confidence interval = [0.29, 0.42], which was reliably above zero but smaller than the meta-analytic mean computed from previous literature (0.67). The IDS preference was significantly stronger in older children, in those children for whom the stimuli matched their native language and dialect, and in data from labs using the head-turn preference procedure. Together, these findings replicate the IDS preference but suggest that its magnitude is modulated by development, native-language experience, and testing procedure.

Infants are highly sensitive to statistical patterns in their auditory language input that mark word categories (e.g., noun and verb). However, it is unknown whether experience with these cues facilitates the acquisition of semantic properties of word categories. In a study testing this hypothesis, infants first listened to an artificial language in which word categories were reliably distinguished by statistical cues (experimental group) or in which these properties did not cue category membership (control group). Both groups were then trained on identical pairings between the words and pictures from two categories (animals and vehicles). Only infants in the experimental group learned the trained associations between specific words and pictures. Moreover, these infants generalized the pattern to include novel pairings. These results suggest that experience with statistical cues marking lexical categories sets the stage for learning the meanings of individual words and for generalizing meanings to new category members.

Statistical learning may be central to lexical and grammatical development: The phonological and distributional properties of words provide probabilistic cues to their grammatical and semantic properties. Infants can capitalize on probabilistic cues to learn grammatical patterns in listening tasks. However, infants often struggle to learn labels when performance requires attending to less obvious cues, raising the question of whether probabilistic cues support word learning. The current experiment presented forty 22-month-olds with an artificial language containing probabilistic correlations between words’ statistical and semantic properties. Only infants with higher levels of grammatical development capitalized on statistical cues to support learning word-referent mappings. These findings suggest that infants’ sensitivity to correlations between sounds and meanings may support both word learning and grammatical development.

Children who rapidly recognize and interpret familiar words typically have accelerated lexical growth, providing indirect evidence that lexical processing efficiency (LPE) is related to word-learning ability. Here we directly tested whether children with better LPE are better able to learn novel words. In Experiment 1, 17- and 30-month-olds were tested on an LPE task and on a simple word-learning task. The 17-month-olds' LPE scores predicted word learning in a regression model, and only those with relatively good LPE showed evidence of learning. The 30-month-olds learned novel words quite well regardless of LPE, but in a more difficult word-learning task (Experiment 2), their LPE predicted word-learning ability. These findings suggest that LPE supports word-learning processes, especially when learning is difficult.