What are the 'carry over effects' in changing from a procedural to a declarative approach?

Highlights are presented of the carry-over effects in changing from a procedural to a declarative approach. The results of a case study of programming in Prolog for a relatively simple problem are reported. The different methods that the subjects used to solve the problem are described. It is argued that they can be explained on the basis of strategies used for problem decomposition and the choice of data representation. It is also argued that the methods of solution used suffer from a carry-over effect based on a procedural approach and, in particular, that the choice of data representation used appears to be more important than the paradigm used.<>