Infant Categorization and Early Object-Word Meaning
Although most researchers would agree that language acquisition is the product of mental processes, few would attempt to explain language learning by relying exclusively on nonverbal cognition. As Johnston (1985) pointed out, "The challenge instead is to identify the specific points, if any, at which developments in nonverbal cognition help determine the course of language acquisition" (p. 962). Despite the fact that there is no existing Piagetian model of language acquisition, Piaget's view of language development has been highly influential. According to Piaget, language plays a major part in the child's representation of the world and is a manifestation of the semiotic function, the ability to process information on a representational level, as opposed to an action level (Piaget, 1962). Among the other cognitive abilities emerging with the advent of the semiotic function are deferred imitation, mental imagery, symbolic function, and drawing. Piaget argued that the capacity to learn words and the capacity to learn rules to put those words together into sentences build on the cognitive achievements of the sensorimotor period. In other words, cognition is a prerequisite for language. Elaboration of the constructivist view of language learning that was held by Piaget can be found in Piatelli-Palmarini, 1980.