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.