We report a series of experiments using a new methodology to investigate the relationships between visual and verbal representations and the process of acquiring new semantic associations. Transfer of associative information between stimulus modalities was investigated by training paired associations between novel pictures and novel words. Our results showed that the transfer of associations is a symbolic process, occurring only when participants are aware of the correspondence between the visual and the verbal items afforded by the name relations. We also obtained evidence to suggest that symbolic associations develop more readily from picture associations than from word associations. We argue that this is evidence that semantic knowledge is grounded in perceptual experience. Our most striking result, replicated across experiments, is that transfer of associations between modalities only occurs when subjects have specific conscious awareness about the relationships among associations. This should have implications for cognitive theories of symbolic representation. The methods we developed to expose this phenomenon can be extended to examine those implications more thoroughly. We discuss some of these implications in the terms of competing and complementary cognitive and behavioural theories relating representation to perception and symbols. Dual coding models fit our modality-transfer results more readily than single semantic store models, but neither is well suited for interpreting our awareness results, or for iv discussing perceptual grounding of representation. The models of Deacon and Barsalou both focus on systems of distributed representations grounded in perception; the role of awareness in symbol acquisition in their models is discussed and contrasted with theories from the stimulus equivalence tradition of behaviourist research. From these considerations, we argue that implicit associations underpin symbolic associations, but that semantic knowledge is conscious knowledge about the patterns of association which link representations.