Abstract: According to the semantic network theory, three theoretical hypotheses were presented on the influence of functional connections in mental images on design time, design quality, and creativity of design results. A series of adjustable seat conceptual design cognition experiments with 14 postgraduates of mechanical major were conducted to test the hypotheses based on protocol analysis. The results of MannWhitney nonparametric tests show that the more the functional connections among knowledge units in mental images are, the less design time it takes, the higher quality design it produces, and the more creative design it conceives. So all the hypotheses hold.

Key words: mental image, functional connection, design cognition, protocol analysis