STEVEN P. DOW, ALANA GLASSCO, JONATHAN KASS, MELISSA SCHWARZ,
DANIEL L. SCHWARTZ, and SCOTT R. KLEMMER
Iteration can help people improve ideas. It can also give rise to ﬁxation, continuously reﬁning one option without considering others. Does creating and receiving feedback on multiple prototypes in parallel, as opposed to serially, affect learning, self-efﬁcacy, and design exploration? An experiment manipulated whether independent novice de-signers created graphic Web advertisements in parallel or in series. Serial participants received descriptive critique directly after each prototype. Parallel participants created multiple prototypes before receiving feedback. As measured by clickthrough data and expert ratings, ads created in the Parallel condition signiﬁcantly outperformed those from the Serial condition. Moreover, independent raters found Parallel prototypes to be more diverse. Parallel participants also reported a larger increase in task-speciﬁc self-conﬁdence. This article outlines a theoretical foundation for why parallel prototyping produces better design results and discusses the implications for design education.