‘Footprints’ are marks or features of a design that alert the analyst to the possible existence of
usability difficulties caused by violations of design principles. PUMA Footprints make an explicit link between
the theory underlying a Programmable User Model and the design principles that can be derived from that
theory. While principles are widely presented as being intuitively obvious, it is desirable that they should have a
theoretical basis. However, working directly with theory tends to be time-consuming, and demands a high level
of skill. PUMA footprints offer a theory-based justification for various usability principles, with guidelines on
detecting violations of those principles
