There is a clear conflict between making an interface easier to use and making computer-based problems easier to solve. Making the control of the problem-solving domain more complex helps users to reach their solutions in less steps. Previous explanations of this phenomena have been centred in how the interface impacts on learning or planning of the problem solving domain. This paper adds a new element to this work by drawing on observational analysis. Interface differences are closely related to the types of strategy a user employs. A more complex interface makes the user more sensitive to their problem solving situation. Explanations of the phenomena are reconsidered in the light of strategy analysis. The effect occurs in problem solving interfaces because the domain specific requirements of the interface cannot be divorced from the domain independent goals. The application of the effect to design is discussed in relation to several areas.