A good combination of words and images facilitates learning. This is based on the dual coding theory (Paivio, 1971), which uses the idea that humans need either verbal associations or visual imagery to increase learning effectiveness. The theory assumes that we have two specific yet connected cognitive subsystems. One subsystem is specialized in representing and processing nonverbal objects/events (i.e., imagery), and the other subsystem is specialized in dealing with language. To put it simply, the theory discusses how we process verbal and visual information in our brains.
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