Early links in the early lexicon: Semantically related word-pairs prime picture looking in the second year.

With word meanings and word forms paired up like books in their jackets, the human lexicon is a vast and complex library. From its sparse beginnings in infancy, the lexicon incorporates thousands of words and concepts into an efficient processing system. Relationships between words provide an interconnected cross-referencing system, allowing the mature language user to slip between the shelves with ease. For decades, the technique of ‘priming’ has been used to probe organisational characteristics of the adult semantic system. In the priming method, semantic context is systematically manipulated to influence on-line language processing. When sequential activation of particular items alters task performance, inferences can be made about the psychological reality of the relationship between the items – and thereby, inferences about the nature of the system. Both visual and auditory primes are known to influence the speed of lexical access (Antos, 1979; Meyer & Schvaneveldt, 1971; Radeau, 1983) and ambiguity resolution (Swinney, 1979). Various types of semantic relationship have been demonstrated using the priming method, including word association (Moss, Ostrin, Tyler, & Marslen-Wilson, 1995; Nation & Snowling, 1999), taxonomy (Meyer & Schvaneveldt, 1971), shared semantic features (McRae, Cree, Seidenberg, & McNorgan, 2005; Moss, McCormick, & Tyler, 1997), and instrumental relationships (Moss et al., 1995). Thus, facilitation in priming tasks can be understood as a spread of activation between related items in a semantic network (Anderson, 1983; Collins & Loftus, 1975; Meyer & Schvaneveldt, 1976). Yet little is known about the development of the semantic system from first words and concepts, to this complex adult system. Is a system encoding relationships between concepts in place from the early stages of word learning? Or does it arise after extensive experience? Are early relationships adult-like? Or does reorganisation occur? The goal of this chapter is to review recent evidence for adult-like relationships between words in the second year using a recently developed method for investigating the organisational properties of the infant lexicon.