Response to Sloutsky: taking development seriously: theories cannot emerge from associations alone.

In our Opinion piece, we articulated four elements of words that are essential to any theory of acquisition [1]. First, words refer, they do not merely associate. Second, word-meanings incorporate abstract conceptual knowledge (e.g., “intention”, “cause”, “animacy”), as well as sensory and perceptual features. Third, there are different kinds of word (e.g., nouns vs. verbs), each linked to a different kind of concept (e.g., categories of objects vs. events). Finally, words acquire their meaning not only from their histories of co-occurrence with entities in the world, but also from the intricate linguistic and social systems of which they are a part. We amassed evidence from several different research programs bearing on each of these points in children ranging from six months to four years [2, 3] and outlined a detailed developmental trajectory, revealing that conceptual and linguistic capacities are available to preverbal infants and that these become increasingly precise from infancy into the preschool years. Curiously, although each of our four points is contested in Sloutsky's theoretical position [4, 5, 6], he engaged none of them in his response [7]. Neither did he provide a plausible alternative account of specific findings, including for example, that when infants see a set of objects (e.g., red apples) paired with a novel word, they interpret a novel noun as referring specifically to the object category (e.g., apples) and an adjective to an object property (e.g., red). This finding, and others like it, are at odds with Sloutsky's assertions that (1) words are merely features of the objects with which they have become associated, and (2) words (by virtue of their status as auditory information) evoke so global a response in young children as to overshadow visual information. Sloutsky raises two objections, both of which miss their mark. First, he criticizes our proposal, which engages evidence from infancy through the preschool years, as insufficiently developmental. Second, he objects that we fail to account for how early theories arise from “simpler components”. But we reject the assumption that the infants' initial framework theories are constructed from simpler primitives. On the contrary, in our view, initial theories and ontologies (e.g., regarding agency or physical causality) are themselves conceptual primitives, providing strong starting-points in infancy for the more elaborated theories evident later in development. That is, infants establish associations, and make sense of them, within the context of the theories they hold. How does Sloutsky's account fare against his own criticisms? He attributes to infants a capacity to build associations and detect perceptual similarities. But strikingly absent is any account of how theories (which he acknowledges are held by children and adults) could emerge from a bedrock of associations alone. Also absent is a principled account of similarity. In closing, we stand by the developmental portrait we have painted. “As infants and young children build a repertoire of concepts and acquire words to describe them, they [use] both perceptual and conceptual information, and rely upon both the rudimentary theories that they hold and the statistics that they witness.”