Why a Diagram is (Sometimes) Worth Ten Thousand Words
J. H. Larkin, H. A. Simon 1987 Cognitive Science v11 p65-99

Information is processed differently when presented in textual form as compared to in the form of a diagram. In this article, the authors compare informationally equivalent diagrams with texts. The paper discusses at length how this information is processed, and conclude that diagrams have the ability to group information spatially which can reduce the search process as well as supporting perceptual inferences which are difficult to make from text.

This resource is referenced here:
Resource Type: Pedagogic Resources:Research Results, Report
Research on Learning: Ways Of Learning:Visual Learning