Beyond the language explosion: What gradual word learning tells us about conceptual development

For the past 50 years, language acquisition researchers have explored the fascinating question of “the language explosion”: how children are able to rapidly acquire hundreds to thousands of new words in a brief period of time. Focusing primarily on how basic-level nouns, such as “cup”, are quickly mapped to visible objects, researchers have proposed several constraints guiding early word learning. Their insights include the principle of mutual exclusivity, the whole object bias, the principle of contrast, fast mapping, and the notion of “comprehension before production” (e.g., Carey & Bartlett, 1978; Clark, 1988; Markman, 1994). Such work has greatly enhanced the field’s understanding of how rapid early word learning can be achieved. Much less is known about how children acquire words that do not refer to objects, how children’s word meanings may differ from those of adults, and the inferential processes that take children from their initial mappings to adult-like meanings. In striking contrast to the notion of rapid word learning, we here explore the claim that in some cases, despite early production, children require additional months or even years to achieve adult-like comprehension (e.g., Ameel et al., 2008; Saji et al., 2011; Tillman & Barner, 2015; Wagner, Dobkins, & Barner, 2013; Widen & Russell, 2008; Wynn, 1990). This symposium brings together researchers studying five conceptual domains in which children’s word meanings evolve gradually — color, number, emotion, locomotion, and time — to explore the inferential processes children use to overcome their early assumptions and acquire adult meanings. In each case, we discuss how linguistic and perceptual cues come together to aid the construction of an abstract, domain-specific lexical category, how that category grows and gains internal structure, and how this structure in turn constrains and refines the meanings of individual words within it. Imai discusses children’s acquisition of color words, like “red”, which are initially mapped quickly and coarsely to perceptual referents, but whose meanings must then be gradually refined to language-specific boundaries. In a similar vein, Widen considers how children’s use of emotion labels, like “sadness”, narrows as children acquire new words, like “embarrassment”. Chu argues that children initially have inexact meanings for number words, like “four”, long before they acquire their exact meanings and learn how counting works. Malt examines children’s early meanings for locomotion words, like “running” and “jumping”, and finds that although children overextend their early meanings, they rely on cues from the biomechanics of gait to help restrict the set of meanings they consider. Tillman explores how children learn time words, like “hour,” which lack visible referents, increasing children’s reliance on linguistic structure to constrain early meanings prior to mapping the words to experiences. Finally, Shatz, who has examined abstract word learning processes in several of these domains (e.g., Shatz et al., 1996; 2010), will serve as our moderator and discussant. How young children construct the lexicon as a connected system: The case of color names (Imai with N. Saji, M. Asano, Y. Ujihara K. Yasufuku, M. Ebe & M. Ohba) To acquire adult-like word meanings, children need to construct a system in which the clusters of words in each semantic domain are mutually related, while the boundaries among these words are delineated. This is particularly true for the color lexicon. To investigate the full developmental trajectory through which children construct the color lexicon, we conducted two studies. Study 1 examined how children who knew few color words became able to map eight basic color names (red, blue, yellow, green, purple, pink, brown, orange) to their typical referents, by testing children every month, starting at 24-months of age and ending when the child was able to map all eight words correctly.. In Study 2, three-, 4-, and 5-year-olds and adults were tested on their naming of 93 samples of both chromatic