In spoken languages, children acquire locative terms in a cross-linguistically stable order. Terms similar in meaning to in and on emerge earlier than those similar to "front" and "behind," followed by "left" and "right." This order has been attributed to the complexity of the relations expressed by…

Differences in socioeconomic status (SES) correlate both with differences in cognitive development and in brain structure. Associations between SES and brain measures such as cortical surface area and cortical thickness mediate differences in cognitive skills such as executive function and language. However, causal accounts that link SES, brain,…

The words in children's language learning environments are strongly predictive of cognitive development and school achievement. But how do we measure language environments and do so at the scale of the many words that children hear day in, day out? The quantity and quality of words in a child's input are typically measured in terms of total amount…

Most theories of learning would predict a gradual acquisition and refinement of skills as learning progresses, and while some highlight exponential growth, this fails to explain why natural cognitive development typically progresses in stages. Models that do span multiple developmental stages typically have parameters to "switch" between…

The literature on human and animal learning suggests that individuals attend to and act on cues differently based on the order in which they were learned. Recent studies have proposed that one specific type of learning outcome, the highlighting effect, can serve as a framework for understanding a number of early cognitive milestones. However,…

There are clear associations between the overall quantity of input children are exposed to and their vocabulary acquisition. However, by uncovering specific features of the input that matter, we can better understand the mechanisms involved in vocabulary learning. We examine whether exposure to "wh"-questions, a challenging quality of…

This article reports the structure of associations among 101 common verbs and body parts. The verbs are those typically learned by children learning English prior to 3 years of age. In a free association task, 50 adults were asked to provide the single body part that came to mind when they thought of each verb. Analyses reveal highly systematic…

The emergence of shared symbol systems is considered to be a pivotal moment in human evolution and human development. These changes are normally explained by reference to changes in people's internal cognitive processes. We present 2 experiments which provide evidence that changes in the external, collaborative processes that people use to…