ABSTRACT
This chapter explains how dual coding systems help us to survive and thrive in everyday life. It is based on strong and consistent effects of variables that justify DCT while challenging other theories of cognition. The review also provides empirical grounds for the interpretation of cognitive evolution in later chapters. The description of these adaptive functions elaborates on the principle of cooperative independence, the idea that the verbal and nonverbal systems, although functionally independent, must coordinate their activities to achieve common goals. This is a version of the truism that the adaptive mind must function in an integrative fashion. DCT provides a principled approach to how this is achieved. Independence means that the systems can be active separately or together. Cooperation is possible because each system can activate the other via their interconnections. Cooperative independence implies (a) additive benefits of verbal and nonverbal activity in some tasks, (b) selective reliance on one system when it is especially relevant to a given task, and (c) switching back and forth between them according to changing task demands. Such cooperative activities of the two multimodal systems usually serve us well, but, under some conditions, one system might not be helpful and could even interfere with the efficiency of the other. All these possibilities are illustrated with research examples. A summary of the methods used to measure and manipulate the internal systems is followed by a review of dual coding contributions to memory, anticipation, evaluation, motivation, problem solving, and communication—viewed here as the basic adaptive functions of mind.
