commonalities between code comprehension
and generation activities
Simon P. Davies
Department of Psychology
University of Hull, Cottingham Road,
Hull, HU6 7RX, UK
This paper reports an experiment on the comprehension of computer programs viewed through a limited access window by novice and expert programmers. The intention of the study was to explore the role played by the external environment in mediating the cognitive processes involved in computer programming.
Previous work by the author Davies ( 1993) using a text editor which only allowed movement between adjacent lines in a program, hence enforcing a strict linear generation strategy, showed that this device restriction can systematically affect error patterns and solution times in a code generation activity. Moreover, this effect was more marked for experts than for novices, suggesting potential disruption to 'normal' problem solving strategies.
This finding may be explained in terms of display-based competence ( Larkin, 1989). Models of display-based competence suggest that part of the process of becoming an expert involves developing strategies which lead to extensive extemalisation behaviour ( Davies, 1996; Green et al, 1987) where information is output to some external source, rather than rely upon working memory. In contrast, novices appear to extemalise little and their comprehension, whilst