Samenvatting
A detailed look at the representations constructed by novice and expert computer programmers is presented. The issue is addressed by looking at the interaction between the representation naturally formed by programmers at each level of expertise and an experimentally induced abstract or concrete "mental set". The data suggest that, in the absence of an experimentally provided set, experts form abstract representations (defined here as what a program does), whereas novices form concrete representations (defined here as how a program functions).