Seda Yilmaz 1 Department of Industrial Design, Iowa State University, 146 College of Design, Ames, IA 50010 e-mail: seda@iastate.edu Colleen Seifert Department of Psychology, University of Michigan, 3042 East Hall, Ann Arbor, MI 48109 e-mail: seifert@umich.edu Shanna R. Daly College of Engineering, University of Michigan, 210 Gorguze Family Laboratory, Ann Arbor, MI 48109 e-mail: srdaly@umich.edu Richard Gonzalez Department of Psychology, University of Michigan, 426 Thompson Street, Ann Arbor, MI 48109 e-mail: gonzo@umich.edu Design Heuristics in Innovative Products Current design theory lacks a systematic method to identify what designers know that helps them to create innovative products. In the early stages of idea generation, designers may find novel ideas come readily to mind, or may become fixated on their own or exist- ing products. This may limit the ability to consider more and more varied candidate con- cepts that may potentially lead to innovation. To aid in idea generation, we sought to identify “design heuristics,” or “rules of thumb,” evident in award-winning designs. In this paper, we demonstrate a content analysis method for discovering heuristics in the designs of innovative products. Our method depends on comparison to a baseline of exist- ing products so that the innovative change can be readily identified. Through an analysis of key features and functional elements in the designs of over 400 award-winning prod- ucts, 40 heuristic principles were extracted. These design heuristics are outlined accord- ing to their perceived role in changing an existing product concept into a novel design, and examples of other products using the heuristics are provided. To demonstrate the ease of use of these design heuristics, we examined outcomes from a classroom study and found that concepts created using design heuristics were rated as more creative and var- ied. The analysis of changes from existing to innovative products can provide evidence of useful heuristic principles to apply in creating new designs. [DOI: 10.1115/1.4032219] 1 Introduction Exciting product designs depart from what is currently on the market [1]. For this reason, one design strategy is to generate as many creative solutions as possible that fit the problem require- ments in the initial concept generation phase [2]. By generating multiple alternative concepts with varied features, the designer can then select the best prospects for further development. One estimate is that only 8% of development costs are incurred during the early design phase; yet, decisions made in this phase deter- mine up to 70% of the total cost over the product’s life [3]. Per- haps as a result, researchers have investigated the cognitive processes that occur in the concept generation phase of design cre- ation [4–10]. While a common ideation technique in industry is traditional team brainstorming [11], a growing body of research has identified its limitations [12]. Designers can also become “fixated” [13–16], where their attention is focused on a single past example or on one new idea. How do designers generate more and more varied concepts in order to produce product innovations? Design expertise is a complex subject to study empirically because the creative process appears unpredictable and opportun- istic [17]. But studies of expert designers have uncovered some of the behaviors associated with the generation of designs: An expert designer draws upon precedents [18], is able to restructure a design problem space through transformations [19], makes long interrelated chains of moves (and retrieves larger knowledge chunks from memory) [20], and identifies “clues” to good designs [21]. Experts within a domain learn to incorporate a variety of cognitive changes that improve performance [22,23]; in particular, they learn to use domain-specific, implicit knowledge derived from their experiences [24]. This implicit knowledge in expertise appears to take the form of simple rules of thumb used to generate a judgment or decision [25]. While the term “heuristic” more commonly refers to strategies that use existing information to guide search in problem-solving [26], cognitive heuristics are “best guesses” at potential solutions and are not guaranteed to lead to a determinate solution. Psychological research shows that experts use cognitive heuristics constantly and effectively, and their effi- cient use of domain-specific heuristics distinguishes them from novices [27]. For example, an expert firefighter arrives at a scene and instantly recognizes what approach to take to the fire based on implicit knowledge built from many experiences with other scenes; then, that knowledge serves as a heuristic to direct action in this novel setting [28]. The cognitive heuristic directs behavior in the new setting, though it is not certain to be successful. We draw upon this concept of cognitive heuristics to describe an experience-based rule of thumb in memory that can be useful in suggesting new design concepts, called design heuristics [29,30]. In this approach, specific cognitive heuristics are posited as implicit knowledge based on past experiences that help the de- signer to explore the solution space of potential designs [30,31]. Successively applying different design heuristics assists in creat- ing different candidate concepts from this potential design space. We propose that expert designers employ design heuristics in order to enhance the variety, quality, and creativity of potential designs they generate during the ideation stage. In a case study of an expert practitioner working on a two-year project, we examined the designer’s work as captured in his pro- gression of designs recorded on a scroll such that related designs appear in adjacent positions. By closely analyzing the progression of concepts in the scroll, a large number of different design heuris- tics were identified [31]. This designer appeared to have acquired design heuristics that could be applied to create multiple new con- cepts. The concept sketch in Fig. 1 illustrates one design heuristic from this study. In the retrospective interview, the designer com- mented, “… more homes in the world have existing bathtubs than have an open room. I was inventing a new toilet and but then I got practical and said you know, wait a minute, while it’s fun and nice, everyone else already has a tub. So can I do some of that this way adding onto an existing tub?” By “adding on” snap-on trays onto the bathtub for the needed functions, using the heuristic 1 Corresponding author. Contributed by the Design Theory and Methodology Committee of ASME for publication in the JOURNAL OF MECHANICAL DESIGN. Manuscript received February 13, 2015; final manuscript received November 11, 2015; published online June 1, 2016. Assoc. Editor: Carolyn Seepersad. Journal of Mechanical Design JULY 2016, Vol. 138 / 071102-1 Copyright V C 2016 by ASME Downloaded From: https://mechanicaldesign.asmedigitalcollection.asme.org/pdfaccess.ashx?url=/data/journals/jmdedb/935307/ on 02/17/2017 Terms of Use: http://www.asme.or