The effects of time and incubation on design concept generation

•More ideas and a greater variety were found with additional time (2 h versus 50 min).•A two-day incubation period helped novice designers break fixation.•For higher quality concepts, additional consecutive time is better than incubation.•For more novel concepts, additional consecutive time is better than incubation.•For efficiently generating novel, feasible solutions, a 50-min session is best.

The optimal length and format for concept generation is largely unknown. One experiment compares a 50-min session to a 2-h session, observing that senior undergraduates generate more ideas and a greater variety of solutions with additional time, although high novelty solutions are developed within the first 50 min. A second study finds that more novel solutions are generated after an incubation period, although it is at the expense of feasibility. Comparing the two studies shows that incubation generates a greater quantity of ideas, while extended time aids in high quality and novelty. Since the 50-min and 2-h groups generate similar numbers of high quality and high novelty solutions, a 50-min ideation period is effective for developing high quality, novel solutions.