External information sources in computer programming. The role of textual and graphical representations in support of complex problem solving activities

A number of emerging accounts of problem solving behaviour in complex domains have emphasised the role played by the external environment in the mediation of cognitive activity (Latkin, 1989). Theories of display-based problem solving seek to explain certain facets of behaviour by stressing the contribution of external memory sources as repositories for search control knowledge and intermediate state information. The main idea promoted by such models is that display-based strategies can partially supplant a complex goal structure by enabling problem solvers to substitute efficient perceptual operations for unreliable cognitive processes. One area in which the role of display-based problem solving has gained prominence is in the programming domain. This paper presents evidence for differences in the nature of programmers´ information externalisation strategies. Two experiments are reported which suggest that experts rely much more upon the use of external memory sources in situations where the device they use to construct the program hinders the utilisation of a display. Experts tend to externalise low level information, mainly to aid simulation, whereas novices develop higher level representations which might be characterised as transformations or re-representations of the program typically of diagrammatic form. Moreover, in the case of experts the nature of externalised information appears to depend upon whether they are generating a program or comprehending it