Still Suspicious: The Suspicious-Coincidence Effect Revisited.

Imagine hearing someone call a particular dalmatian a "dax." The meaning of the novel noun dax is ambiguous between the subordinate meaning (dalmatian) and the basic-level meaning (dog). Yet both children and adults successfully learn noun meanings at the intended level of abstraction from similar evidence. Xu and Tenenbaum (2007a) provided an explanation for this apparent puzzle: Learners assume that examples are sampled from the true underlying category (strong sampling), making cases in which there are more observed exemplars more consistent with a subordinate meaning than cases in which there are fewer exemplars (the suspicious-coincidence effect). Authors of more recent work (Spencer, Perone, Smith, & Samuelson, 2011) have questioned the relevance of this finding, however, arguing that the effect occurs only when the examples are presented to the learner simultaneously. Across a series of 12 experiments ( N = 600), we systematically manipulated several experimental parameters that varied across previous studies, and we successfully replicated the findings of both sets of authors. Taken together, our data suggest that the suspicious-coincidence effect in fact is robust to presentation timing of examples but is sensitive to another factor that varied in the Spencer et al. (2011) experiments, namely, trial order. Our work highlights the influence of pragmatics on behavior in experimental tasks.

Promoting Replicability in Developmental Research Through Meta-analyses: Insights From Language Acquisition Research.

Previous work suggests that key factors for replicability, a necessary feature for theory building, include statistical power and appropriate research planning. These factors are examined by analyzing a collection of 12 standardized meta-analyses on language development between birth and 5 years. With a median effect size of Cohen's d = .45 and typical sample size of 18 participants, most research is underpowered (range = 6%-99%; median = 44%); and calculating power based on seminal publications is not a suitable strategy. Method choice can be improved, as shown in analyses on exclusion rates and effect size as a function of method. The article ends with a discussion on how to increase replicability in both language acquisition studies specifically and developmental research more generally.

Linguistic structure emerges through the interaction of memory constraints and communicative pressures.

If memory constraints were the only limitation on language processing, the best possible language would be one with only one word. But to explain the rich structure of language, we need to posit a second constraint: the pressure to communicate informatively. Many aspects of linguistic structure can be accounted for by appealing to equilibria that result from these two pressures.

Shaping semantic networks with transcranial direct current stimulation.

Images depict specific objects (e.g., a specific dog), yet are named with categorical labels (e.g., "dog"). We examined how semantic representations activated by images may be influenced by implicit labelling. Participants saw images of familiar objects and generated words associated with each image while undergoing transcranial direct current stimulation over the posterior superior temporal gyrus. Additional participants judged how representative generated associates were of the picture category and guessed the category based on the associates. Anodal stimulation was predicted to up-regulate labelling and thereby increase the extent to which participants produced associate that were more representative of the pictured category. Associates generated by anodally stimulated subjects were found to be more representative and enabled more accurate guessing of the category from which they were generated. The general pattern of results was replicated in a follow-up study using words rather than picture cues. Together these results suggest labelling may help stabilise semantic representations, leading to more robust representation of category-relevant information.

Understanding the effect of social context on learning: A replication of Xu and Tenenbaum (2007b).

Does the source of a piece of data-the process by which it is sampled-influence the inferences that we draw from it? Xu and Tenenbaum (2007b) reported a large effect of sampling process on learning: When a category exemplar was presented by a knowledgeable teacher, learners generalized more narrowly than when it was presented from an unknowledgeable source. In 5 experiments, 4 online and 1 in-person, we attempted to replicate this result. Aggregating across our studies, we replicated the original finding of sensitivity to the sampling process, but with a smaller effect size than the original. We discuss these findings in the context of concerns about replicability more generally, as well as the practical relevance of sampling effects in psychological experiments. (PsycINFO Database Record

The length of words reflects their conceptual complexity.

Are the forms of words systematically related to their meaning? The arbitrariness of the sign has long been a foundational part of our understanding of human language. Theories of communication predict a relationship between length and meaning, however: Longer descriptions should be more conceptually complex. Here we show that both the lexicons of human languages and individual speakers encode the relationship between linguistic and conceptual complexity. Experimentally, participants mapped longer words to more complex objects in comprehension and production tasks and across a range of stimuli. Explicit judgments of conceptual complexity were also highly correlated with implicit measures of study time in a memory task, suggesting that complexity is directly related to basic cognitive processes. Observationally, judgments of conceptual complexity for a sample of real words correlate highly with their length across 80 languages, even controlling for frequency, familiarity, imageability, and concreteness. While word lengths are systematically related to usage-both frequency and contextual predictability-our results reveal a systematic relationship with meaning as well. They point to a general regularity in the design of lexicons and suggest that pragmatic pressures may influence the structure of the lexicon.