The cognitive dimensions framework is a broad-brush evaluation technique for interactive devices and for non-interactive notations. It sets out a small vocabulary of terms designed to capture the cognitively-relevant aspects of structure, and shows how they can be traded off against each other. The purpose of this paper is to propose the framework as an evaluation technique for visual programming environments. We apply it to two commercially-available dataflow languages (with further examples from other systems) and conclude that it is effective and insightful; other HCI-based evaluation techniques focus on different aspects and would make good complements. Insofar as the examples we used are representative, current VPLs are successful in achieving a good `closeness of match', but designers need to consider the `viscosity' (resistance to local change) and the `secondary notation' (possibility of conveying extra meaning by choice of layout, colour, etc.).

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Up until now there has been no agreement on what a mental model of a physical system is and how to infer the mental model a person has. This paper describes research aimed at solving these problems by proposing that a Mental Model is a dynamic representation created in WM by combining information stored in LTM (the Conceptual Model of the system) and characteristics extracted from the environment. Three experiments tested hypotheses derived from this proposal. Implications for research on Mental Model are discussed. Mental Models and Working Memory 3 3 The role of Working Memory on measuring Mental Models of physical systems When a person learns to interact with a system it means she/he acquires knowledge about its operation and about the structural relationships between its components. Researchers have called this knowledge the 'Mental Model' of the system (Moran, 1981). The existence of Mental Models, and their importance during the interaction with the system, has been demonstr...

running head title: Design Strategies and knowledge in OOP * Françoise Détienne is a cognitive psychologist with an interest in software design; she is a researcher in the Ergonomic Psychology group of INRIA. An empirical study was conducted to analyse design strategies and knowledge used in object-oriented software design. Eight professional programmers experienced with procedural programming languages and either experienced or not experienced in object-oriented programming participated in this experiment. They were asked to design a program for a procedural problem and a declarative problem. We have concentrated our analysis on the design strategies related to two central aspects of the object-oriented paradigm: (1) associating actions, i.e., execution steps, of a complex plan to different objects and revising a complex plan, and (2) defining simple plans at different levels in the class hierarchy. As regards the development of complex plans elements attached to different objects,

This paper studies the role of imagery in program comprehension. With this goal we investigated whether theories of mental models from Psychology of Programming (e.g., Pennington’s Two Stages Theory) could be expanded to account for the effect of imagery. Given the basic research in image processing, our hypothesis is that imagery would allow a quicker access to the functional (Data Flow) information of programs. Then, Visual Programming Languages should allow for quicker construction of a mental representation based on Data Flow relationships of a program than procedural languages. To test this hypothesis we ran an experiment where we accessed the mental model of C and spreadsheet programmers in different program comprehension situations. The results showed evidence that the spreadsheet programmers developed Data Flow based mental representations in all situations while C programmers seemed to access to a Control Flow based mental representation first.

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