The background literature presented in the article should offer a clear argument for why the study being reported is necessary. It explains the origins of the research question. When evaluating the introduction, we read the description of the literature carefully and ask whether the literature cited provides good support for the study. We also look at the kind of support offered. Is there a theory that guides the research? Does this study build directly upon previous research? Is it important? Will it make a contribution to the field?

DeLoache, Miller, and Rosengren review a number of studies of symbol use in young children. They report findings that show that young children do not make a connection between a symbol and its referent even when it is pretty obvious (e.g., the relation between a room and its scale model) but that by age 3, most children can use a scale model to make conclusions about the room. They cite the theory of dual representations to explain why symbolic reasoning may develop slowly. Symbolic reasoning requires that the person using the symbol is able to think about the features of the symbol and what it represents at the same time. If the symbol is attractive and has very specific features, this may make it very difficult to think about its abstract nature.