Analogies and Metaphors in Creative Design

In our increasingly flat and connected world, skills in innovation and creative design have
emerged as key attributes for graduating engineering designers. Metaphors and analogies are
commonly voiced as key tools for enhancing creative design yet little research has been
performed on their relation to each other and their use within the design process.

In this paper we discuss the relationship between metaphor and analogy use in the design process, with a focus on engineering education. We support our discussion with results from interviews and experiments with student designers. Our results highlight that both metaphor and analogy are spontaneously used by student designers and that metaphor dominates as the design tool for early problem framing design phases whereas analogy dominates as a tool for concept generation. We also present an analysis of the metaphors for our understanding of design in use within Germany, the UK and Mexico. We found an 85% overlap between textbook usages of metaphors in conceptual design in these countries as compared to textbooks authored in the United States suggesting that cross-cultural differences in design understanding are relatively small in higher education. We close by presenting a design by analogy method to promote and enhance the use of analogy as a skill for graduating engineering designers.

Introduction

The National Academy of Engineering (NAE) recently released two reports on the Engineer of
2020 [1,2] that identify the "flat world” [3] skills needed by engineers in the twenty-first century. These reports emphasize the need for engineers of the future to develop skills in practical ingenuity and creativity as this is what will differentiate them from low wage engineers on the international market. In other words, the top paid engineers will be those that are skilled in developing innovative new products and markets.

Imagine the genesis of a VW Beetle automobile from an insect or a bridge arch from the
structure of a natural cave formation. Metaphors and analogies, such as these, abound in
discussion of innovation and creative design. For example, analogies to nature or existing
products often assist engineers in finding innovative solutions. Figure 1 shows an innovative
design for a bipolar fuel cell plate. The critical functions of the bipolar plate for current
generation are disturbing, guiding and dispersing a fluid over its surface. Leaves have these
same functional attributes and drawing an analogy between the leaf and the fuel cell rapidly
leads the engineer to make use of nature’s experience.

VW Bwwtle

A widely cited design metaphor discussed in [4] tells the story of how the Canon team was
inspired by the metaphor of a beer-can copier. The beer can copier should be as simple and
inexpensive to manufacture as a beer can. The metaphor promoted the idea of keeping the
copier as a shell, where the parts that are more likely to break down are allocated to the
regularly replaced cartridge. In 1981 Apple promoted their new Apple computer as a bicycle for
the mind [5]. More recently, Ryokai [6] and colleagues at the MIT Media Lab developed the
metaphor The World Is A Palette in their project “the I/O brush” (Figure 2). The brush allows
colors, textures and even movements to be captured from the world to create new types of art
and a new experience for the artist.

 Fuel Cell bipolar plate design generated from an analogy to a leaf.

These examples highlight just a few of the ways metaphors and analogies are used. Metaphors
and analogies are also at work in branding, interface design, problem framing, communicating
a common vision and enhancing concept generation. Furthermore, while traditionally
metaphors were seen primarily as literary flourish, recent research has shown that metaphor
usage is both more pervasive and more profound [7,8]. Metaphors affect the way we reason
about such widespread everyday concepts such as time, problems and emotions. Researchers
have also argued that metaphors are fundamental in our understanding of the design process
itself [9].

This figure shows the example of the metaphor “Design As Functional Analysis.” This metaphor
focuses the design process on the functionality of what a product does while hiding many other
important aspects such as how the user interfaces with the product and the products’
aesthetics.

Metaphor and Analogy : Definition for Design

We begin by defining the relative meanings of analogies and metaphors in design. Both
compare a situation in one domain with the situation in another. Gentner and Markman [10]
posit that whereas the fundamental property of analogies is the relational and structural
similarity, metaphors span the spectrum of relational similarity at one end, and appearance
similarity at the other. These definitions do describe analogy and metaphor as used
within the design context, but a key dimension is missing. The key difference is in the elements
that are mapped between domains and how they are used in the design process. Metaphors
frame and assist the designers in defining the design problem. Metaphors are commonly used
to map users’ understanding, activities and reactions to a product. They help make sense of
customer needs or physical attributes from the source of inspiration. Metaphors exceptional
communication ability provides meaning to a design situation; a cafeteria when seen as an oasis for its visitors becomes a different place entirely. Analogy, in contrast, primarily maps the
causal structure between the source product in one domain to the target design problem being
solved. The causal structure includes a devices’ functional solutions, geometry or component
configuration.

Reasoning with Metaphors and Analogy

Analogies and metaphors are usually seen as a mapping between a source and a target domain. The target domain is the domain to be understood. For example, in the Apple

‘Bicycle for the mind’ example, the Target domain is the Apple computer, and the source
domain is the domain of bicycles and travel. When we use this source domain, we evoke a
travel frame, and we are able to tap into our knowledge about bicycles and travel to enrich our
understanding of the Apple computer. For instance, a bicycle helps the body travel further and
faster than before with less effort. By implication, the Apple computer will allow us to perform
more tasks, faster and more in-depth than before with less effort.

Understanding the cognitive process involved in the formation of metaphors and analogies is

important for understanding and improving the design process. Analogy and metaphor can be
viewed as a mapping of knowledge from one situation to another enabled by a supporting
system of relations or representations between situations [10,11,12,13,14]. This process of
comparison fosters new inferences and promotes construing problems in new insightful ways.
The potential for creative problem solving is most noticeable when the two domains being
compared are very different on the surface [10]. Research has been carried out in the field of psychology to understand the cognitive processes people use for creating and understanding analogies and metaphors [15,16,17].

This figure shows the basic process steps involved in reasoning. For illustration this process will be explained as being applied to the design process even though the same cognitive process occurs anytime a person reasons by metaphor and analogy. The process begins when a person learns a new piece of knowledge (encodes the source of inspiration for a future problem). At some future time, the person is faced with a new problem and must retrieve (remember) a suitable idea source to solve the new problem. Retrieving a useful analogy or metaphor is the most cognitively difficult step. Once a source is remembered, a mapping is created between the source and the new target situation. By developing these mappings we create new inferences.

Past Empirical work on Analogy

Design methods require a deep understanding of the processes people use and the areas where guidance or assistance could improve the process. This knowledge is gained through a
combination of experimental work and naturalistic observation. Even though design-by analogy

is a well-recognized method, few experiments focus exclusively on analogy in design.
Notable results from these experiments, however, include the work of Casakin and
Goldschmidt [18], Ball et al. [21], Kolodner [19], and Kryssanov et al. [20]. Casakin and
Goldschmidt found that visual analogies can improve design problem solving by both novice
and expert architects [18]. Visual analogy had a greater impact for novices as compared to
experts. Ball, Ormerod, and Morley investigated the spontaneous use of analogy with engineers
[21]. They found experts use significantly more analogies than novices do. The type of analogies used by experts was significantly different from the type used by novices. Novices
tended to use more case-driven analogies (analogies where a specific concrete example was
used to develop a new solution) rather than schema-driven analogies (more general design
solution derived from a number of examples). This difference can be explained because novices have more difficulty retrieving relevant information when needed and have more difficulty mapping concepts from different domains due to a lack of experience [19].

Prior research in analogical reasoning found the encoded representation of a source analogy

(the analogous product) can ease retrieval if it is remembered such that the key relationships
apply in both the source and target problem domains [22,23].The analogies and problems used
in these experiments were not specific to any domain of expertise and used fantasy problems
relying on strictly linguistic descriptions. The encoded representation result was replicated for
realistic design problems [24,25,26]. It was further shown that the representation of the design
problem had a significant impact on a designer’s ability to retrieve an analogy and multiple
representations of the design problem will ease analogical retrieval [26]. These studies show
that representation plays a key role in memory retrieval and therefore also in design by analogy. By understanding the influence of representation, design by analogy, and likely also
metaphor use, can be enhanced through well-designed methods and tools.

Design is understood with Metaphor

Because much of the discourse in design uses abstract concepts such as problems, solutions and ideas, we naturally use metaphors when we talk and reason about design and the design

process itself. When a design team lists constraints to put boundaries on the design space they are using metaphor. In this case, we reason that design takes place in a bounded space of
possibilities.

Yet different metaphors provide us with a different understanding of design. For example,

design researchers and authors have proposed alternative metaphors to design as search [27]
including design as a process of selection [28], design as a process of exploration [29], design as bricolage [30] or design as a journey [31].A designer who sees design as a process of selection is more likely to list options and then select between them, whereas a designer who views design as a process of exploration is more likely to generate and test a number of options, iterating towards a solution.

It is important that we, as design educators, are conscious of the perspectives on design that we pass to our students. For just as metaphors can serve as effective vehicles for communication among design teams, a disconnect in metaphors can serve to increase confusion between designers. Our flat and connected world [3] is characterized by increasing collaboration between designers from different countries and cultures. Accordingly we investigated whether designers from four different countries share a common understanding of creative design. Our data to this understanding are the different metaphors employed in popular design textbooks in use in these countries. As much of our basic reasoning is structured through metaphor, analyzing metaphors in common use provides insight into the way we understand and act upon these concepts [32].

For example, an author that stresses design as decomposition is more likely to refer to problems as objects (that can be broken down, solved in parts and reassembled). This metaphor stresses techniques like functional decomposition. Whereas an author that sees design as a process of search is more likely to see problems as locations to be avoided or gaps to be bridged in that space.

Cross-Cultural Comparison of Design Process Metaphors

To determine whether US design students are taught similar perspectives on design as other

countries, we broke down the analysis in [9] to six US design textbooks [33,34,35,36,37,38], one from Germany [39], and two from the UK [40,41]. In addition, for the purposes of our analysis here, we analyzed an additional Spanish design textbook in use in Mexico [42].

We followed the three phase process outlined in [9]: (1) Extracting instances of metaphors from

design texts; (2) Categorizing the metaphor instances; then (3) Identifying the coherent
metaphors that make sense of the metaphor instances. In total over 430 individual metaphor
instances were extracted from the textbooks. Each of the analyses was conducted on the English translation of the textbooks with the exception of [42] which was evaluated by a bilingual
researcher. The researcher extracted instances in Spanish and translated these for comparison with the remainder of the analysis.

To obtain a better feel for the analysis, here are two examples of metaphor instances:

Brainstorming is meant first of all to trigger off new ideas, but it cannot be expected to produce
ready-made solutions because problems are generally too complex and too difficult to be solved by spontaneous ideas alone. [39, p78]

In the above phrase, the design concepts of ‘ideas,’ ‘problems’ and ‘solutions,’ as referred to

metaphorically, are underlined. The metaphorical qualifiers to each of these concepts are
highlighted in italics. In the analysis, we listed all the qualifying statements for each design
concept. In the example above, “Ideas” can be triggered off, new, spontaneous and can solve
problems; “problems “ can be complex, and difficult; “solutions“ can be produced and ready-made.

This table able illustrates that the textbooks from Germany, Mexico and the UK share an 86.5% overlap of qualifiers for ‘ideas,’ ‘problems’ and ‘solutions’ with those present in the US textbooks. What this means is that the three design concepts are conceptualized in largely the same ways across these different design cultures.

The overlap in design metaphors reflects a largely consistent Western approach to design. We

speculate that the global reach of information and the widespread use of English in academic
design discourse play a key role in the apparent uniformity of current views on design. For
example, while the Mexican design textbook was written in Spanish, it reflects many of the
design ideas present in US textbooks that originate largely from within the US or Europe. While
this consistency may be beneficial to global collaborations, we believe it may also have a
limiting effect on the development of new ways of thinking about design, especially within
higher education.

Analogies and Metaphors in the design processes

Metaphor as a tool for problem framing and solution generation

Other than affecting our high-level understanding of the design process, metaphors are a

commonly touted design tool. Metaphors can be used at different stages of the process, both in
the early stages as a tool for better understanding the design situation, and also as a solution
generation tool.

For example, seeing a cafeteria as an oasis not only helps understand the situation but leads to
new solution directions. The designer might consider how the feeling of an oasis could be
better supported by the cafeteria, perhaps by providing places for rest or better closing it off
from the outside world. In another example, a shower might be seen as a reset for the person
taking the shower. They wash away the rest of the day and start renewed once they emerge.
The metaphor, Shower Is A Reset, can be used to generate other solutions that could support
people’s feeling of starting anew even to the point of activating the shower with a button.

Analogy use in concept generation

Wing Warping

Wright Brother invented the Wing Warping inspired by the bicycle tube box. This is the example of how transfer from source (known) to target (unknown).

In contrast to metaphor, analogies tend to be used during the concept generation to find

solutions to the design problem rather than to frame or assist in understanding it. Analogies to
nature and previous designs are common. For example, a team with the design problem of
creating a device to fold laundry may make analogies to other types of folding devices such as
paper folding or metal folding. Analogies also support concept selection. When a designer is
evaluating a set of concepts, they will typically reference design they have seen before in their
evaluation. In other words, the designers use analogies to predict the performance of the
design concept.

Metaphor and Analogy use by new product development teams

We conducted interviews with 12 multidisciplinary new product development teams from a

graduate course at the University of California, Berkeley. Teams were composed of business,
engineering or informationscience and industrial design students. The teams worked on new
product development projects loosely following the process outlined in [33] from initial project
idea, conducting user research, to presenting a user-tested prototype at a final tradeshow.
Eleven interviews were performed in the final two weeks of the project and one was performed
after the final tradeshow. Interviews were conducted with the full team present when possible,
and the teams were asked to tell the story of their project from beginning to end explaining the
key points as they saw them along the way. Although the group format has the potential to
inhibit some group members from contributing, in practice it served to engender a rich
discussion among the team as they each added to the story as they saw it. Interviews were then
recorded, transcribed and coded for discussion of relevant product, not process, metaphors and use of analogy.

Though there was no formal teaching of metaphor use in design, 8 out of 12 design teams
highlighted a metaphor in the problem framing stage as an important factor in their project.
For example, one team, developing a software product for social networking, searched for a
suitable comparative business and used photo-sharing: “we saw it as organizing your collection
of pictures, which is very tedious to do but once you have it nice to have. So that’s what we
thought we were trying to do with networking … it’s kind of annoying to do networking all the
time but it’s nice to have a social network in the end.” Extending the photo-sharing comparison
the team explained “we were the Flickr of social networking - And it just helped us frame the
whole process.”

A team investigating electronic textbook delivery developed a restaurant metaphor to help

understand their design situation and the student experience. “Educational content was like
food in a meal. And so the publishers are like chefs in the kitchen preparing the content and
because there’s an agency problem the professors order for you and so then you get served – so there are three aspects to the student experience – it’s getting served the content, eating and digesting the content and then enjoying the content as in discussing it after the fact. It was
actually quite relevant because we had to talk about how do you serve things up versus how do
you facilitate some of the ability to access them and digest them on their own and then share
those thoughts.”

(Chef in Kitchen ) : (Customer in Restaurant) :: (Professor in Class) : (Student in University)

From this relationship, we can easily customers can choose different meals in the restaurant is like the student can select different courses in the university.

Another team began with the goal of developing software that would help designers see

manufacturing errors in CAD models before they went to manufacture. As one member
explained: "If the user is making a model using CAD software the software will do the error
detection in real time and give the feedback in real time. Something like a spelling checker in
Microsoft Word. It does it in the background…"

One team, looking for opportunities to integrate computing into the kitchen developed a

platform-based solution after realizing from their research that the kitchen was an organic,
messy space: “I think sort of what our platform has become is tailored for picking this section of
the problem. And then you know the rest can grow out from there because it’s an organic
space. It’s a messy space. It’s not supposed to be very regimented, it’s the kitchen. It allows for
some freedom there.” The insight of the organic nature of the kitchen directed the team towards
the flexible platform solution.

Further examples include a team that explored developing a NASCAR style fast food drivethrough experience, and a team developing a device to remove blood clots that viewed the situation as akin to plumbing – they were creating pipes.

Analogy and metaphor use by designers during concept generation

For comparison to the metaphor use data, we coded the use of analogy from a prior study

where design teams were asked to use a particular group idea generation technique and then
spend forty minutes generating solutions to a design problem [47]. All the group idea
generation techniques evaluated for the study required teams to use only written
communication. This study was a 3 X 2 factorial design. The first factor controlled the
representation teams used for communication (words only, sketches only, or a combination).
The second factor controlled how team members exchanged ideas, either all the ideas were
posted on the wall or each team member had a sub-set of the ideas and they rotationally
exchanged them. Teams consisted of five senior mechanical engineers. The experiment asked
the teams to design a device to shell peanuts.

The analogy coding was based on clear references to other designs, such as “analogy to potato peeler” or “this is like a grill”. This approach underestimates the actual number of analogies used by the design teams. Designers frequently use analogies without making explicit references and frequently without realizing the source of their idea [48,25]. In addition, the coding can not evaluate if the analogy was being used as an explanation tool or if the idea had been developed based on the analogy. A common use of analogy is to explain an idea rather than as an original source of inspiration [48].

Comparison of metaphor and analogy use

Example of analogies teams used to assist in designing a device to shell peanuts.

• “Staple remover design”
• “rotating blade shells peanut (analogy to potato peeler)”
• “Similar function to putting your hand in a bicycle chain, except your hand is replaced by peanuts”
• “maybe like two pencil sharpeners that are put opening to opening”
• “the peanuts can be collected with a device that attaches to a bike and acts like a golf ball picker-upper-thingy.“
• “A rolling type of mechanism, much like a Roots-Style supercharger, with rubberized “fingers” or slots,… the peanuts are fed by gravity into the roller, hopefully the shells are crack.”
• “A rolling mechanism like a ball bearing grinding machine. Two large round plates with spiral grooves cut into them that spin at a fixed distance from each other and in opposing rotational directions. “
• “Use a device with two pliers like shell crackers opposing each other.”
• “Develop a large clamping platform with a bottom stationary plate and an opening/closing top plate (like a Foreman Grill ™).

Metaphors were most frequently used to frame the design situation whereas analogies were
most common for generating solutions to the design problems. Although these data are not
sufficient to prove this trend, the result is compelling and warrants further investigation. Our
data support Casakin’s results that students had an easier time employing metaphors to assist
in framing their problem as opposed to using it to generate solutions [46]. The data from the
new product development interviews illustrated use of metaphor in the early problem framing
stages of the design process. For example, the ‘Flickr of social networking,’ the education
restaurant metaphor, and the manufacturing spellchecker metaphor allowed the teams to see
their design situation in a different way. The metaphors helped frame the design situation for
the teams. This is in contrast to the results of the analogy study that showed how analogy
contributed directly to the development of new solution concepts rather than providing an
understanding of the design situation.

The prevalence of metaphor in the early stages of the design process may stem from the teams’ search to understand a complex human design situation. A metaphor helps bring structure to the design situation and acts as a meaningful communication tool to the rest of the team. The metaphor helps the design teams figure out a story that makes their design project make sense. In contrast, the concept generation phase is often concerned with more technical aspects of design problem solving where the emphasis is on finding a technical solution that will work rather than a story to help make sense.

Extended Applications and Implications for Education

The way in which engineers conceptualize individual design problems and the overall design
process affects the end results. Metaphors used to describe and understand the design process stress certain aspects such as “design is decision making” while concealing others. This can lead to too much or too little emphasize on particular steps in the process. Metaphors and analogies employed within the design process on a particular product also highlight particular elements of the design or of the design space.

The analysis of metaphors found in British, American, Mexican and German engineering
design textbooks shows that the design process is conceptualized in largely similar ways across these cultures. This has an important implication as engineers work in a global environment. One key challenge in working in a global environment is that engineers define and solve problems differently [49]. Our analysis shows that engineers across these countries will likely conceptualize the overall design process in similar ways and thus this is less likely to be a point of conflict.

The data in this paper on analogy and metaphor along with the prior empirical work show the
importance of both analogy and metaphor in the design process. Professionals frequently use
both in the design process [5018,51]. Students need to be taught how to effectively employ
analogies and metaphors symbiotically in the design process. Formal design methods do exist
for using both analogy and metaphor in design [52,53,54,55,56]. Current design-by-analogy
methods give little guidance on how to find analogous products or require the creation of a
database of prior solutions [54,55]. Design methods for metaphor also leave the finding of a
suitable metaphor to the team’s experience. Our results suggest that tools and methods to assist in the search process for suitable analogies and metaphors would benefit designers.

The above Figure is a basic method based on prior empirical research for seeking analogies
to assist in solving a design problem. Our prior research shows that by creating multiple
representations of the design problem, designers are more likely to think of a larger set of
analogies that can be used to solve it [26]. Our methodology symbiotically uses metaphors and
analogies. The process begins with an initial problem statement. The initial problem statement
may be created with any approach, for example customer needs gathering, see [37]. Once a
design team has an initial problem statement they then use metaphors to reframe the problem
in other ways. For example if the problem statement was to “Design a Device to Fold Laundry
for People with Serve Disabilities” a metaphor could be thinking of Laundry as a Game. The
design problem would include making the process enjoyable. The use of metaphors then leads
to multiple problem statements.

First a design team generates ideas for other ways of stating or thinking about the design problem. Then the teams find synonyms for the key words in their problem statements using a thesaurus or WordNet [57]. WordNet has the advantage of also connecting to more general or domain specific ways of stating the same thing. If the design team contains members who are
multilingual then the design problem may also be represented in other languages. This process
results in numerous linguistic representations of the design problem. The design team then uses these representations to generate analogies and solutions to the design problem. The
variety of representations prompts a wide variety of ideas.

Finally the various linguistic representations are then used for key word searches in various
databases such as patent databases, the web, or a function database [58]. If design teams have multilingual team members then this provides access to other patents databases and a greater set of information.

Conclusions and future work

This paper assists future design engineers by explicating the roles of analogy and metaphor in
creative design. We clarified the distinction between metaphor and analogy in the design
process. Metaphor use is primarily for enhancing understanding of a design situation by
transferring meaning. Analogy, in contrast, primarily maps the causal structure between the
source product in one domain to the target design problem being solved. Results from our
interview and experiment data show that student designers use both analogy and metaphor
within the design process without formal training. More significantly, the results suggest that
metaphor use is primarily employed in the early problem framing stages of design. Conversely,
analogy is mostly used in the concept generation phase of design.

We also discussed the influence of our metaphor on our understanding of design itself.
Analysis of the metaphors used in popular design textbooks from Germany, the UK andMexico showed an 85% overlap in metaphor usage with those in US textbooks. This result
suggests that cross-cultural differences in the understanding of design between design teams
are likely to be small.

Further studies will be performed on the use of metaphor and analogy in different stages of the
design process to determine the robustness of the results presented here. The design by analogy method presented will be tested and its effectiveness measured in creative design.

Authors’ Biographies

Jonathan Hey is a Ph.D. candidate at the Berkeley Institute of Design at the University of
California at Berkeley. He is fascinated by learning how to make things people really want and
understanding creative design. His research focus is how product development teams come to
a shared frame of the problem that is worth solving.

Julie Linsey is a Ph.D. candidate in the Mechanical Engineering Department at The University
of Texas at Austin. Her research focus is on systematic methods and tools for innovative and
efficient conceptual design with particular focus on design-by-analogy.

Alice M. Agogino is the Roscoe and Elizabeth Hughes Distinguished Professor of Mechanical
Engineering at UC Berkeley. She has served in a number of administrative positions at UC
Berkeley, including Associate Dean of Engineering and Faculty Assistant to the Executive Vice
Chancellor and Provost in Educational Development and Technology. She also served as
Director for Synthesis, an NSF-sponsored coalition of eight universities with the goal of
reforming undergraduate engineering education, and continues as PI for the NEEDS
(www.needs.org) and smete.org educational digital libraries. Agogino leads a number of
research projects in the areas of computational design, learning sciences, wireless micro-sensors MEMS, green design and diagnostics and monitoring. She has authored over 150 scholarly publications; has won 3 teaching and 9 best paper awards; is a member of the National Academy of Engineering and a recipient of the NSF Director's Award for Distinguished Teaching Scholars. She has supervised 68 MS projects/theses and 28 doctoral dissertations.

Kristin Wood the Cullen Trust Endowed Professor in Engineering at The University of Texas at
Austin, Department of Mechanical Engineering. Dr. Wood’s current research interests focus on
product design, development, and evolution. The current and near-future objective of this
research is to develop design strategies, representations, and languages that will result in more comprehensive design tools, innovative manufacturing techniques, and design teaching aids at the college, pre-college, and industrial levels.

Acknowledgements

The authors would like to acknowledge the support provided from the Cullen Endowed
Professorship in Engineering, The University of Texas at Austin and the National Science
Foundation under Grant No. CMMI-0555851. Any opinions, findings and conclusions or
recommendations expressed in this material are those of the authors and do not necessarily
reflect the views of the sponsors. The authors would also like to thank Emily Clauss for her
assistance with the literature review and Dr. Vicente Borja for his evaluation of metaphors used
in design textbooks in Mexico.

Source : Analogies and Metaphors in Creative Design