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Empirical audit and review is an approach to assessing the evidentiary value of a research area. It involves identifying a topic and selecting a cross-section of studies for replication. We apply the method to research on the psychological consequences of scarcity. Starting with the papers citing a seminal publication in the field, we conducted replications of 20 studies that evaluate the role of scarcity priming in pain sensitivity, resource allocation, materialism, and many other domains. There was considerable variability in the replicability, with some strong successes and other undeniable failures. Empirical audit and review does not attempt to assign an overall replication rate for a heterogeneous field, but rather facilitates researchers seeking to incorporate strength of evidence as they refine theories and plan new investigations in the research area. This method allows for an integration of qualitative and quantitative approaches to review and enables the growth of a cumulative science.

Multiple approaches – including observational and experimental – are necessary to articulate powerful theories of learning. Our field’s key questions, which rely on these varied methods, are still open. How do children perceive and produce language? What do they encounter in their linguistic input? What does the learner bring to the task of acquisition? Considerable progress has been made for the development of spoken English (especially by North American learners). Yet there is still a great deal to discover about how children in other populations proceed, especially populations in rural settings. To examine language learning in these populations, we need a multi-method approach. However, adapting and integrating methods, particularly experimental ones, to new settings can present immense challenges. In this paper, we discuss the opportunities and challenges facing researchers who aim to use a multimethodological approach in rural samples, and what the field of language acquisition can do to promote such work.

Inspired by Syrett (2013), three experiments explored children's ability to distinguish attributives (e.g., \"three-pound strawberries,\" where MPs as adjectives signal reference to attributes) versus pseudopartitives (e.g., \"three pounds of strawberries,\" where MPs combine with of to signal part-whole relations). Given the systematic nature of the syntax-semantics mapping, we asked whether children are able to use syntax to interpret how entities are quantified. In Experiment 1, four- and five-year-olds were asked to choose between two characters for the one who was selling appropriate items matching an attributive or pseudopartitive expression. In Experiment 2, children of the same age heard items described with a phrase using either an attributive, a pseudopartitive, \"each\" (\"each weighs three pounds\"), or \"all together\" (\"all together they weigh three pounds\"). At test, with some items removed, children were asked whether the same phrase applied to the remaining items (e.g., \"Does Dora still have three-pound strawberries?\"). Children did not distinguish between attributives and pseudopartitives but did so for \"each\" and \"all together.\" Experiment 3 extends the age range with a third experimental design. Children heard \"each\" or \"all together\" descriptions (e.g., \"each strawberry weighs three pounds\") and judged, at test, which of two characters \"said it better\" (i.e., \"Mickey says 'these are two pounds of strawberries,' but Donald says 'these are two-pound strawberries.'\"). Children under 6 were at chance. Together, the three experiments suggest that despite its systematicity, children do not automatically appreciate the mapping between syntax and semantics.

Children’s early speech often bears little resemblance to that of adults, and yet parents and other caregivers are able to interpret that speech and react accordingly. Here we investigate how adult listeners’ inferences reflect sophisticated beliefs about what children are trying to communicate, as well as how children are likely to pronounce words. Using a Bayesian framework for modelling spoken word recognition, we find that computational models can replicate adult interpretations of children’s speech only when they include strong, context-specific prior expectations about the messages that children will want to communicate. This points to a critical role of adult cognitive processes in supporting early communication and reveals how children can actively prompt adults to take actions on their behalf even when they have only a nascent understanding of the adult language. We discuss the wide-ranging implications of the powerful listening capabilities of adults for theories of first language acquisition. The authors use a computational model of word recognition to show that adults’ interpretation of young children’s speech depends heavily on beliefs about what children are likely to say.

Children are famously scrappy learners: curious, active, and resourceful. And yet when we consider their development of language — a complex social system that children are highly motivated to master — we tend to study them as passive recipients of adult guidance. This overlooks language development as a fruitful domain in which to study children’s self-directed learning, as well as insights that recent active learning frameworks could bring to language development. In this dissertation, I discuss language development as a coordinated process between communicative adults and increasingly active learners. In particular, I see children’s learning from speech not directed to them, but rather overheard, as a uniquely ecologically valid test case of their self-directed learning capabilities. A combination of experimental and computational studies from this perspective speak to an apparent paradox in the language development literature: while studies testing correlations between sources of language input in toddlers’ home environments and later vocabulary growth have been taken to indicate that overheard speech is ineffective for word-learning, numerous experimental studies show in-lab learning from simplified indirect speech during the same period. The idea, borrowed from experiments with infants, that children may disattend to stimuli that are too complex for their current level of competence may help explain these conflicting results. That is, young rational learners may initially learn little from overhearing because the speech that surrounds them is too complex to maintain their attention — especially when compared to the speech that they receive in interactions with adults.A first study compares multiple empirically-motivated metrics of speech complexity in largescale longitudinal child-directed corpora, and overheard speech simulated via corpora of adult-adult conversations. We find that words in simulated overheard speech are likely to be less concrete, more unpredictable, later-acquired, and lower frequency than words in speech to children. This is likely to be true through at least the first four years of life, spanning the period when measurements of overheard speech quantity in children’s environments have repeatedly been found to be unrelated to children’s early vocabularies.Across three studies in the second chapter, we test children’s ability to learn from dense, naturalistic overheard speech in a context designed to place significant demands on their self-directed learning abilities, including their spontaneous recognition of an “information gap” and independent information-gathering. In contrast to previous laboratory experiments — but consistent with many overhearing opportunities day-to-day — the speech we used included multiple pieces of novel linguistic information, embedded in diverse sentence structures, and delivered in the register and rate typical of adult-adult conversations. While all children in our sample were able to learn a set of 5–6 novel facts, only older preschoolers (Mage = 5.1 years) demonstrated robust learning of novel words through overhearing. Analyses of children’s play and gaze behavior during the overhearing episode suggest that older children’s success is owed at least in part to their enhanced ability to coordinate attention between the referential context and the nearby speech.In the third chapter, we develop a novel method to test the classic idea that children learn best from information that is of an appropriate level of complexity for them, and in particular the role that children themselves might play in actively selecting and attending to potential sources of information. By measuring children’s attention to a story narrated at distinct levels of verbal complexity — operationalized in terms of words’ estimated age of acquisition — we find evidence that children attend more to speech that is more appropriate for their level of competence. Furthermore, while previous research has assumed that children’s attention and learning are meaningfully related, our method provides direct evidence, as children’s self-directed attention to the story predicted their comprehension of and ability to learn new words from it.Inspired by qualitative studies typically limited to child-directed speech, in the fourth chapter, we develop a coding scheme that enables us to characterize the full range of potential sources of language accessible to a given child, in terms of their relative utility for word-learning. In applying this scheme to longitudinal video data from the home of a single English-learning child, we find that features that contribute to the referential transparency and salience of an utterance (in and out of the laboratory), are not exclusive to child-directed speech, but rather occur with some lower frequency in overheard speech as well. In light of this, our analyses suggest a functional role for caregivers’ exaggerated prosody in distinguishing speech intended for the child, and as a self-reinforcing cue to language where the child’s attention is likely to be rewarded. Through this fine-grained coding of individual utterances in context, our results thus uncover dynamics in how adults and children co-structure the early language environment — and how the landscape itself shifts with the child’s maturation — which are otherwise hidden from more quantitative approaches.Ongoing work extends the ideas in the dissertation to new contexts and populations, be-ginning by employing the same scheme to describe crosslinguistic learning environments, facilitating contact with more humanistic fields like anthropology. The fifth chapter adapts existing measures of implicit word knowledge to test culturally specific language knowledge in Tseltal Maya infants, who primarily overhear. While the preceding chapters challenge our assumptions of how language is typically learned, this work aims to expand our (testable) notions of what counts as legitimate language knowledge. The experimental studies in this dissertation share a focus on using naturalistic speech and ecologically valid contexts, and together point to the role of domain-general processes like attention, information processing, and learner adaptation in the course of language development.

Children's early speech often bears little resemblance to that of adults, and yet parents and other caregivers are able to interpret that speech and react accordingly. Here we investigate how these adult inferences as listeners reflect sophisticated beliefs about what children are trying to communicate, as well as how children are likely to pronounce words. Using a Bayesian framework for modeling spoken word recognition, we find that computational models can replicate adult interpretations of children's speech only when they include strong, context-specific prior expectations about the messages that children will want to communicate. This points to a critical role of adult cognitive processes in supporting early communication and reveals how children can actively prompt adults to take actions on their behalf even when they have only a nascent understanding of the adult language. We discuss the wide-ranging implications of the powerful listening capabilities of adults for theories of first language acquisition.

How do adults understand children's speech? Children's productions over the course of language development often bear little resemblance to typical adult pronunciations, yet caregivers nonetheless reliably recover meaning from them. Here, we employ a suite of Bayesian models of spoken word recognition to understand how adults overcome the noisiness of child language, showing that communicative success between children and adults relies heavily on adult inferential processes. By evaluating competing models on phonetically-annotated corpora, we show that adults' recovered meanings are best predicted by prior expectations fitted specifically to the child language environment, rather than to typical adult-adult language. After quantifying the contribution of this \"child-directed listening\" over developmental time, we discuss the consequences for theories of language acquisition, as well as the implications for commonly-used methods for assessing children's linguistic proficiency.