In order to effectively communicate information, the choice of representation is important. Ideally, a chosen representation will aid readers in making desired inferences. The ability of diagrams to convey information effectively comes, in part, from their tendency to make facts explicit that would otherwise need to be inferred. This diagrammatic benefit has often been referred to as a free ride, which has recently been generalized to the notion of an observational advantage. In this talk, I will present the theory of observation – capturing when one statement is observable from another – which exploits relations between syntactic elements of representations that convey meaning. Using the concept of observability as a basis, I will give a formal characterization of the observational advantages of one representation over another. By considering observational advantages, people will be able to make better-informed representation choices. To exemplify the theory, I will show that Euler diagrams sometimes have numerous observational advantages over set-theoretic statements. This formally justifies Larkin and Simon’s claim that “a diagram is (sometimes) worth ten thousand words”.

This is joint research with Atsushi Shimojima and Mateja Jamnik.

Gem’s interests are firmly situated in the study of diagrams, encompassing their mathematical properties and cognitive effectiveness. Her multi-disciplinary research aims to expose how we can effectively design and apply diagrammatic representations in order to communicate, and reason about, information. She is perhaps best known for her ground-breaking contributions towards the development of diagrammatic logics alongside methods to automatically draw diagrams as visualizations of information. Gem’s current research is creating novel mechanisms to facilitate representation change in order to enhance human understanding. As leading figure in the Diagrams community, Gem has been highly influential in the direction of diagrams-related research as well as the Diagrams conference series. Having previously been Director of the Visual Modelling Group at the University of Brighton, she is now a Visiting Fellow at the University of Cambridge.