The role and impact of mental simulation in design

Although theories of mental simulations have used different formulations of the premises of ‘thought experiments’, they can be fitted under a minimalist hypothesis stating that mental simulations are run under situations of uncertainty to turn that uncertainty into approximate answers. Three basic assumptions of mental simulations were tested by using naturalistic data from engineering design. Results from the design protocols showed (1) initial representations in mental simulation had higher than base‐rate uncertainty, (2) uncertainty in mental simulations were lowered after simulation runs, (3) resulting representations had more approximations than base‐rate or initial representations. Further, the reference to external representational systems (sketches and prototypes) was examined. It was found that prototypes had fewer technical/functional simulations compared to sketches or unsupported cognition. Although prototypes were associated with more approximation than unsupported cognition, the different external representation categories did not differ in information uncertainty. The results support the minimalist hypothesis of mental simulations. Copyright © 2008 John Wiley & Sons, Ltd.