DEVELOPING A METHODOLOGY FOR DESIGN FORAESTHETICS BASED ON ANALOGY OF COMMUNICATION

Ernest J. J. van Breemen Imre HorváthWillem G. Knoop Joris S. M. Vergeest

Delft University of TechnologySubfaculty of Industrial Design Engineering

Jaffalaan 9, NL-2628 BX Delft, The NetherlandsPhone: +31 15 278 3520Fax: +31 15 278 1839

E-mail: i.horvath@io.tudelft.nl

Binh Pham

School of Information Technology & Mathematical SciencesUniversity of Ballarat

PO Box 663 Ballarat, VIC 3353, AustraliaPhone +61 3 5327 9286Fax +61 3 5327 9289

Email: b.pham@balarat.edu.au

Abstract

Although attempts have already been made, computer support of industrial design isstill in its infancy, especially of design for aesthetics. The reason is that nomethodology is available to incorporate in computer support, design aspects likeappearance, pleasantness and human usage of a product. The objective of the paperis to present a methodology that facilitates development of computer support ofdesign for aesthetics. While a designed product can trigger definite aestheticresponses to observers, it is not easy to relate these responses to the characteristicsof the product. For that reason the paper focuses on the issues related to a practicalcoupling of intended aesthetic impressions and shape design. First it summarizes thefundamentals and knowledge related to aesthetics. Then it compares two studies onphenomenological and systematic approaches that have been carried out to modeluser responses to products and to identify possibilities for designers to influencethose responses with the geometric design of products. Based on the generalizationof the experiences a novel methodology for unifying aesthetics and design isintroduced following the analogy of information communication. The problem ofrealizing aesthetic intents is decomposed into an activity loop that extends tostatistical, syntactical, semantical and pragmatic levels of communication. Ourinitial experiments and tests have shown that the information communicationanalogy helps understanding the core problem of design for aesthetic and supportsthe elaboration of a quasi-formalized methodology that serves well as a base ofcomputer tool development.

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1 Introduction

The roots of understanding the aesthetics of natural and artificial things trace back to thedistant past. Some two thousand years ago, the roman architect and artist Vitruviusclaimed that, for human products, ‘firmitas’, ‘utilitas’ and ‘venustas’ are the keyingredients, as well as their harmony. Henry van de Velde, a Belgian architect anddesigner, said “Beauty is the result of clarity and system, and not an optical illusion” (DeWolff, 1992). Mijksenaar (1997) developed a scheme to measure the relative strength ofthese qualities for industrial design products. Nevertheless, the most fundamentalinterrelations have not been fully explored and clarified yet. There are severalassociations to explain, e.g., how the aesthetic quality is experienced: based onunconscious visual perception or, on the contrary, based on rigorous analysis andcomparison with already acquired patters; what is the system of qualities we are lookingfor in an aesthetically pleasing product; what are the rules of formation of aesthetics; orcan the qualities delivered by aesthetics be matched against any set of formalizedexpectations.

In pursuit of developing increasingly complex products for a global market where thecompetitive products deliver almost the same functionality and where completelydifferent aesthetic expectations are to be fulfilled, design for aesthetics gets more andmore emphasis. With balanced prices, aesthetics is often the only factor that makes adifference and results in success or failure. Nevertheless, design for aesthetics is in lackof the proper understanding of the theoretical fundamentals and the needed computersupport. Naturally, designers want to incorporate aesthetic intents into their products,but there are several problems they have to deal with. First, we have to mention thediversity of possible responses of customers to a single product. Even if the targetedgroups of users are specified and their expectations are circumscribed, it is still an openissue how to translate the aesthetic properties that evoke the requested response to aproduct.

One source of vagueness is that the language to describe aesthetics is very rich, diverseand fuzzy, where one term may have a number of meanings to different people, or manyterms may imply the same or very similar meaning. Another reason is that manydifferent characteristics of the product may act singly or in combination to evoke theresponses. Furthermore, the responses may depend on other factors besides the productitself such as previous experiences or cultural background of the observers. The latterbecomes more clear when we consider the aesthetic response as a feeling basedresponse. According to Frijda (1986) feelings influence actions and that is what happenswhen we respond to an aesthetic stimulus for instance an action to buy a product.However, feelings are very personal so it can be explained that personal experiences andcultural background have their impact on the aesthetic response. We thus need toidentify the characteristics of aesthetics and products that are relevant to the task ofdesign for aesthetics.

Our research into the state of including design for aesthetics into product design anddevelopment explored different approaches. The most elementary, and most widespreadin the industry, relies completely on the aesthetic education and intention of the productdesigners. Other approaches are based on various levels of understanding therelationship between aesthetic and design. The methods that are focusing on one or

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several aspects of design for aesthetics, but do not strive after being comprehensive orexhaustive will be referred to as phenomenological methods. Those however, that intendto cover all aspects and to put together all means in order to be able to manipulate ashape for the sake of achieving a particular impression and/or feeling will be calledsystematic methods. The authors are going to present details about how these methodsare applied in the practice and how much they support design for aesthetics.

Computer-aided conceptual design and shape design is expected to support designaspects other than covered by conventional Design for X techniques. Aesthetic design,together with design for ergonomics, user friendliness, adaptability, etc. is one of thefields which will surely be in the focus of the research and development in the nearfuture due to its role in enhancing product acceptance. These aspects however fallalmost completely out of the scope of the recently existing CAD technology. In thebackground of the observed situation are the following facts: (a) the explicit request forcomputer support in the field of design for aesthetics emerged only a couple of yearsago, (b) relationship between shape and aesthetics as well as between geometric andpsychological aspects is not fully understood neither from theoretical normethodological point of view. To provide effective computer support to this field ofconceptual and shape design, on the one hand, proper understanding of aesthetics isneeded and, on the other hand, a computer-orientated design for aesthetic methodologyis required. In this paper the authors explore the factors that influence the reasoning onand process of design for aesthetics. Based on their initial investigations they present aframework and a methodology that help develop of proper computer support.

Chapter 2 starts with identifying the characteristics of aesthetics and products that arerelevant to the task of design for aesthetics. This chapter also presents some findingsfrom past research and distinguishes two ways (phenomenological and systematic) ofcoping with the relation between aesthetics and shape. These two approaches arerespectively elaborated in chapters 3 and 4. Our experiences lead to the proposition of amethodology for mapping aesthetics and shape in chapter 5. The theory of the Jacobianmatrix is used to create a mathematical foundation. Finally, in chapter 6, we will discusshow our proposed methodology can be applied to the development of computer supportfor aesthetic design.

2 Background on aesthetics and shape

2.1 Aesthetic characteristics

The term ‘aesthetics’ is broadly used to describe the characteristics of the appearance ofa design. In particular, it refers to the responses that indicate the degree ofdiscrimination in perception when people are confronted with the design. Thisperception depends on individual interpretation which may arise from emotionalresponses or comparison with previous experience. Ruskin (1971) discussed thecontrasts between the discriminatory manner of this type of perception (e.g. by artists)and the cursory manner of normal perception. The latter type is more utilitarian andignores information that is not essential for everyday life.

The concept of aesthetics has been extensively analyzed by philosophers for the lastthree centuries, e.g. Kant, (1790), Tolstoy, (1960), Bearsdley, (1958). Early theory oftaste in the eighteenth century sees aesthetics as reactions in an observer, that are

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triggered by a specific kind of object. Thus, five essential components are involved:faculty of perception, faculty of reaction, an object to be perceived, a mental stateresulted from reaction to the object and a judgment of taste. On the other hand, theattitude theory believes that the appreciation of aesthetics is more subjective andrequires certain modes of perception or consciousness from the observer (Dickie, 1974).The concepts of style and originality are also often connected with aesthetics. Chen andOwen (1997), propose a method to systematically describe style profiles of products. Astyle refers to designs which possess a number of recognizable common characteristics(e.g. Art Deco), while taste refers to personal preferences, sensitivity or appreciation ofcertain type of beauty or style. Although the originality of style gives rise to the singularindividuality of a design and often enhances its value, aesthetics does not necessarilyimply originality or vice versa.

Beardsley (1958) who viewed aesthetics as a philosophy of criticism, gave a thoroughanalysis of aesthetic objects in literature, visual arts and music, and discussed the natureof critical evaluation of aesthetics. Since then, many philosophers have attempted toformalize the properties and meanings of aesthetics for evaluative purposes. Goldman(1995) proposed a classification of evaluative aesthetic terms into the following eightcategories:

• Broadly evaluative, e.g. beautiful, ugly, sublime, dreary.• Formal, e.g. balanced, graceful, concise.• Emotional, e.g. sad, angry, joyful, serene.• Evocative, e.g. powerful, stirring, amusing, hilarious, boring.• Behavioral, e.g. sluggish, bouncy, jaunty.• Representational, e.g. realistic, distorted, artificial.• Perceptual, e.g. vivid, dull, flashy.• Historical, e.g. derivative, original, conservative.

These terms which have been used for art criticism and evaluation, describe clearly thetypical reactions of an observer to an object. What seems to be elusive is the relationshipbetween these terms and the characteristics of the object in question. It has beencommonly accepted by many researchers in this field of philosophy that there are threebasic characteristics of the work (like product characteristics in design) that could beused for evaluation: expression, representation and form. An art work (or a design) isexpressive if it arises some emotion from an observer. This emotion may be embeddedin the work by an artist (or a designer) on purpose or unintentionally. Representationrefers to the content of the design art work (design), which may be actual, idealized orimagined, while form refers to the totality of the shape and the structure, organizationand composition of an object. Representation and form are the most easily identifiableproperties. Stiny and Gips (1978) later proposed another category called transparencywhich refers to cases where the reactions to art works (designs) depend on not only theirrepresentations, but also on what the representations may evoke via association withother elements such as emotions, experiences or ideas. Although these discussions weremainly concerned with art work such as music, painting, drawing and literary work, theideas are also relevant to creative product designs by industrial design engineers.

‘Aesthetics’ of a product is an intangible aspect which heavily influences the feelingbased responses. If we want to link the aesthetics to tangible product characteristics we

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need to describe the product in an aesthetic dimension. We have seen that it is possibleto formulate aesthetic variables which can span the aesthetic dimension in which theproduct is represented. However, care has to be taken in working with these variables,because the danger exist that the (subjective) variables represent only a subset of thetotal aesthetic space and might also be interdependent. In the studies we present inchapter 3 and 4 it is seen, for instance, that two different sets of aesthetic variables areused to describe a product.

2.2 Product characteristics

Since product design is a constructive process, we need to examine the characteristics atthe most basic level to be of use for integrating aesthetic intents with design. We believethat the three most basic characteristics that influence the aesthetics of a product are:shape, composition and physical attributes. High-level characteristics such as style orfashion may be dealt with by expressing them in terms of these three basiccharacteristics.

Shape, form and geometry are ambiguous terms. Even the Websters dictionary cannotgive a precise description of shape and form. Both terms are mixed in the descriptionsand used in a tautological way. In the framework of this paper we therefore start withdefining geometry as the lowest level explicit description of a three dimensional pointset in space. It is in fact the mathematical documentation of points, lines, surfaces, etc.Topology and morphology are placed on the same level as geometry, because theyprovide us exact descriptions on the structure, and specific properties of geometricelements. We could say that besides spatial specification, geometry has no furthercontribution and only supports the aesthetic-shape mapping process.

Geometry

Form

Shape

Composition

Physical Attributes

Aestheticcharacteristics Influences

Supports

Expresses

{ (x1,y1) , (x2,y2) , (x3,y3) }

Triangles

Shape feature

Figure 1 Product characteristics and the interaction with aesthetic characteristics.

One level above the geometry we find form, which is to our definition a categoricalrepresentation of global properties of the geometry. It is a more generalized descriptiveterm. An example of form is a triangle, as it is a category of geometries existing as threeinterconnected straight lines. The relation between geometry and form is unidirectionalin the sense that one form represents multiple (and in fact infinitive) geometries but a

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geometry has only one form. In the case of a product form typically influences theaesthetic characteristics.

Shape is seen on a higher level than geometry as well. But in contrast to the globalcharacteristics, shape is defined as the totality of local characteristics of the geometry.So shape is an abstract generalization of the local geometric properties. The localgeometric properties are shape features which form the basis for shape manipulation ona semantic level. An example of shape is the star-like object in Figure 1. This object is aset of sharp edges, the local shape features, which indeed make the object a star. Inrelation to aesthetic characteristics the role of shape is to express them.

Referring to the above definitions composition expresses how shape features arearranged and therefore act on the same level as shape with respect to the aestheticcharacteristics. Guidelines for good compositions which have been recommended byartists and designers for attaining visually pleasing and interesting objects (e.g. Ruskin,1971), may be deployed for analyzing and comparing aesthetic characteristics of design.

Physical attributes such as colour, texture, lighting conditions or material propertiesalso influence aesthetic characteristics, in a similar way as shape does. In fact they adddifferent attributes to the shape and contribute to the total impression of an object.

Typically, many aesthetic descriptive terms are shared by more than one of the threemain characteristics, with distinct meanings. For example, both shape and colourcharacteristics may be described as being `harmonious’. Some physical attributes alsodepend directly on shape characteristics (e.g. color appearance), hence cannot beexamined in isolation from shape. The main difference to the before mentioned aestheticcharacteristics is the tangibility of the product characteristics which provides for aformal description in computer algorithms. As stated before it is the geometry whichmakes shapes tangible and supports the formalization process.

Although the terms to describe aesthetic characteristics are rich and complex, webelieve that the essence of these terms can be related to the three basic characteristics ofobjects, individually or in combination. Since our aim is to provide a generalmethodology to include aesthetic aspects into product design, it seems to be practical,for the time being, to concentrate on how these basic characteristics of a productinfluence the appreciation of its aesthetics, and to leave out other aspects.

2.3 A brief review of the past research

A survey of literature has revealed that although researchers have analysed the conceptof aesthetics for over three hundred years, these efforts generally were concerned withmusic, painting, drawing and literary work. Very few attempts were focused on design(e.g. Pye, 1995), and even less explored the relation between aesthetics and shape.

In psychology and philosophy many studies have been focused on emotions and feelings(Frijda, 1986). In marketing research many studies try to explain consumer behavior,develop models of customer (subjective) judgments (Snelders, 1995, de Bont, 1992) andreliable ways to gather marketing intelligence to incorporate in product design. In civilengineering several attempts have been made to develop systems to design aestheticallypleasing bridges and dams (Furuta, et al., 1993, 1995, Reich, 1993, Miles et al., 1993).In the realm of industrial design Claessen (1996) has explored the relation of color andshape. Kurango, et al. (1992) developed a system to obtain a computer model from

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sketches or mock-up 3D-models. Wallace and Jakiela (1993), Takala and Woodward(1998) and recently Hsiao and Chen, (1997), have suggested computer oriented methodsthat help develop products by using aesthetic intentions or sketches and develop theseinto detailed designs, using knowledge of customers, design processes and, to someextent, knowledge of translating those into new products.

Our literature survey shows that there exist several alternatives of inclusion of aestheticaspects into the design process of consumer products. A part of the research work triedto include psychological aspects (e.g., observation, feeling) to connect shape andaesthetics. The other part endeavors to explain the phenomena of raising emotionstowards a product by assuming a physically determined relationship between aestheticfeatures and the design variables governing the geometry. From a design methodologicalpoint of view, these can be distinguished as phenomenological approaches andsystematic approaches. Phenomenological techniques work on a intuitive level and donot strive after a deep understanding of the role of shape features in controlling feelingsevoked. On the other hand, systematic techniques tackle the problem penetratingly,rather than superficially only. The objective is to form a methodology based onscientific exploration, procedural formalizing and involvement of computing.

A common feature of both intuitive and systematic methods is applying experiments toconsumers, designers, products and processes. The reason of the existence of theseindirect and direct methods is the lack of understanding of and agreement on what is theintrinsic relationship between aesthetic features and design parameters of products. Inshort, no objective method of managing aesthetics is known since aesthetics proved tobe a subjective, relative and phenomenological category. Nevertheless, researchers havebeen making efforts for unification of aesthetics and design both in theory and inpractice.

3 An example of the phenomenological approach

3.1 Fundamentals of the study

Desmet (1998) uses theory from psychology of emotions to model user responses toproducts, and identifies possibilities for designers to influence those responses with thedesign of products. The goal is to help design products with an "emotional benefit" andis illustrated in the field of mobile phones. The study is based on a theoretical model ofhow people’s "feeling based responses" emerge, and clarifies the relation betweenfeelings and products. Based on the theoretical considerations Desmet proposes thefollowing phases in product development to design products with an emotional benefit:

• Determine customers' profile(s) of initiating and additional needs and theirresulting expectations. Do these conflict or correspond with meanings of theproduct, and what are the functional attributes desired by the customers (-groups).

• Make categories of corresponding customer profiles.

• Determine the intended "feeling based response" of every customer group.

• Determine how these responses are based on product characteristics.

• Incorporate these product characteristics in requirements for new designs.

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The study shows how the so-called expression profiles of two groups of customers weredetermined and translated to product requirements. Based on this data new designs wereproposed and responses to them were measured

3.2 Determination of the target user profile

To determine customer profiles Desmet studied (based on Reynolds and Gutman, 1988)how the general meaning a product expresses, acts as stimulus on three levels:attributes, consequences and end-values. In this study mobile phones are analyzed, andcustomers are interviewed with laddering techniques to determine what structure ofmeaning these products have for a group of customers.

The study resulted in categorization of customers into two "care styles": TrendFollowers and Security Seekers. These two groups of people have distinct expectations.Trend Followers want a product to impress others, want to balance their patterns ofspending money, time and energy, and want freedom of movement. Security Seekersexpect their products to provide calmness, no stress, they do not want to attractattention, want to help people in distress, and want to maintain a good relationship withother people. A common expectation is that they also want mobile phones to complywith their search for a balance in spending money, time and energy.

The found expectations together with remarks during the interviews lead to:

• relevant initiating and additional needs

• desired consequences of using a mobile phone

• lists of functional attributes of mobile phones, concerning memory, batteries,design, size, range, user interface and costs.

Care Style: Expectations to be expressed by product characteristics:

Security Seekers Calmness, no stress; unobtrusive

Profile of expressions Shape characteristics

sober block like; no curved surfaces, nolarge fillets

professionalbusiness-like

subdued surface; colors black or darkgray

reliable no small parts, robust i.e.: nothingpointing out, no sharp edges

pleasanteasy

large display; few keys, with one clearfunction, in rows and columns

Table 1 Example of the expression profile and related shape characteristics used togenerate concepts for new mobile phones.

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The design the SecuritySeekers look for in a mobilephone is restraint, sober,pleasant with a business-like,professional expression. TheTrend Followers want an eye-catching, cunning design,looking both professional andwhimsical, with lots of funand contrasts. Both groupswant small size products eachfor their own reasons: SecuritySeekers for reasons ofunobtrusiveness anddiscretion, to be able to carryit anywhere; Trend Followersfor making a better impressionbecause small is moreexpensive looking.

Finally, to make the customersexpectations operational, twoexpression profiles wereassembled compiling termsthat summarize what the products should express with the help of terms the customersused (Table 1). The shape characteristics are determined in an experiment in which bothcare style groups were confronted with eight existing mobile phones. The experimentlead to a selection of a ‘feeling based response’ based on measured feelings and aranking of the products. The response to these products was measured with aninstrument based on the work of among others Izard (1972), who distinguishes thedimensions "Activation" and "Pleasantness" to characterize feelings. The instrumentuses non-linguistic means for subjects to express their feelings about a product (seeFigure 2, Source: Larsen and Diener, (1992), based on Russell, (1980), and Watson andTellegen, (1985).).

The results of this experiment was that Security Seekers had a pleasing calm feelingwith the product of their preference, whereas Trend Followers had a pleasing arousedfeeling. These responses were taken as the feelings that new products should evoke inthe target groups.

3.3 Translation of intended feelings to and appraisal of the newdesigns

Desmet concluded that, because the concerns and intended feeling based responses aredifferent for the two care style groups, no single product can be developed to produce anemotional benefit for people in both groups. He continued by using the extendedexpression profiles, together with (designer specific) collages to design some 26concepts of new products of which he selected 8 to progress with. These were developedinto four shape alternatives: (see Figure 3). Two were developed to evoke intended

arousedastonishedstimulatedsurprised

activeintense

high activation

Low activation

pleasantunpleasant

enthousiasticelatedexcitedeuphoriclivelypeppy

happydelightedgladcheerfulwarmheartedpleased

quiettranquil

stillinactive

idlepassive

dulltired

drowsysluggish

boreddroopy

unhappymiserable

sadgrouchygloomy

blue

distressedannoyed

fearfulnervous

jitteryanxious

relaxedcontentat restcalmsereneat ease

activatedpleasant

affect

inactivatedpleasant

affect

inactivatedunpleasantaffect

activatedunpleasantaffect

Figure 2 The circumplex of affect, a space with thedimensions "activation" and "pleasantness”

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feelings: “Logica” to evoke a pleasingcalm feeling in Security Seekers;“Helix” to evoke a pleasing arousedfeeling in Trend Followers. The othertwo were added for validationpurposes, and were designed to evokepleasing aroused feelings in SecuritySeekers (“Argus”) and pleasing calmfeeling in Trend Followers (“Luna”).The translation of the selectedintentions to a new product design wasdone by using the shape sensitivitygathered by performing the research,using collages and Desmets’ designskills to generate ideas and concepts toselect for continuation of the study.This is the most intuitive part of theprocess.

The designed products were then presented to the subjects who again expressed thefeelings they experienced using the circumplex of emotions. Additionally the subjectsstated their relative preference for the designs, and gave a judgment on the issues in theexpression profiles. The analyzed data resulted in an overview of the responses in thecircumplex of feelings, an overview of the ranking, profiles resulting from the judgmenton aspects, and a factor analysis of the data. All analyses resulted in the conclusion thatthe framework developed lets the designer influence the ‘feeling based response’ ofrespondents by means of the shape of the product. The study has not explained howeverwhat is to be done with a different product and a different cluster of users.

4 An example of the systematic approach

4.1 Fundamentals of the study

In this section we present a systematic approach that is also intended to link aestheticsaspects and geometry. The work is extracted from the BriteEuRam project on InnovativeStyling Applications in Computer Aided Environments (INSTANCE). The basic aim ofthe project was to investigate and compare expression and (perceived) geometry for bothstylistic sketches and the resulting products in automotive design. Muller (1997) alreadyargued that for instance the division of space between the wheel, the driver seat and theposition of the engine, in the design of sports cars, evokes certain feelings. He illustratesthat a symmetric space division radiates peace and balance while an asymmetric divisionleads to feelings of dynamics. However, despite the arguments no formalisedmethodology is mentioned to link these aesthetic characteristics with the definition ofgeometry. The scope of this study is limited to the aesthetic-to-shape relation. A subsetof the aesthetic characteristics is compared with perceived geometric data. In this waywe are able to discuss about part of the relation from aesthetic characteristics to shape orthe understanding how aesthetics evokes feeling (the upper path in Figure 8).

Figure 3 The newly designed mobile phones

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The representative samplein this study was takenfrom 5 differentautomotive projects andconsisted of a conceptsketch and a photograph ofthe finished prototype (seeFigure 4). Six subjects (3automotive designers, 3industrial designers) wereinvolved for judging thematerial. The two subjectgroups, five different cardesigns and also thedocumentation of theinitial product idea andprototype of a single carcould be compared. Thisallows for datainterpretation along thethree dimensions: subjects,designs and productdevelopment phase.Among the challengingquestions that were to beanswered in this studywere:

(a) What is the relationbetween expressionand geometry in automotive design?

(b) Can we explain differences in expression by those in geometry?

(c) How does expression/geometry propagate through a design process?

(d) Is there a difference in the interpretation of two different groups of designers?

4.2 Measuring aesthetic characteristics

The aesthetic focus of the study was the perceived expression by the subjects, whichwas broken down into four terms: aggressive, friendly, functional and elegant. Theseterms are frequently used in automotive industry and cover most of the expressivequalities of cars, although questions can be raised about the independence of thesesubjective aesthetic terms and the completeness of the description of the aestheticdimension by these variables. In reference to the aesthetic dimensions which werementioned in section 2.1 we think that the terms used in this study represent a subset ofthe complete space of aesthetic characteristics.

Each subject was confronted with the stimuli and appointed a value between 0 and 4 foreach expressive term, in which the following meaning was given:

Figure 4 Concept sketches and prototypes that wereused as stimuli.

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0 - not at all aggressive, friendly, functional or elegant

1 - not very aggressive, friendly, functional or elegant

2 - neutral

3 - quite aggressive, friendly, functional or elegant

4 - very aggressive, friendly, functional or elegant

aggressive friendly functional elegant

sketch product sketch product sketch product sketch product

car1 3.7 3.2 0.2 0.8 0.0 0.7 2.0 1.8

car2 2.5 2.3 1.8 2.7 2.0 2.8 3.2 3.2

car3 2.2 0.5 1.5 2.2 3.7 3.8 3.0 0.7

car4 2.8 2.3 2.0 2.7 2.8 3.2 2.0 1.5

car5 3.7 3.3 0.8 0.7 0.5 1.3 2.7 1.5

Table 2. Average results for the expressive terms for all stimuli.

For each expressive term table 2 gives the judgment for the sketch and the productprototype of each car. The values are the averages for all subjects. All car sketches areperceived more aggressive and elegant while the prototypes are experienced as morefriendly and functional. We will further discuss the values of table 2 in section 4.4.

4.3 Determination of the product shape

The shape of the product in this study is practically the perceived shape. For both thestylistic sketches and the photographs of the prototypes the perceived surface ismeasured by the method described by Koenderink, et al. (1992, 1995). Basically theydeveloped the method to extract three dimensional surface information from theperception of two dimensional images.

In this method a subject is sitting behind acomputer monitor which displays an image of thestimulus. By adjusting a pushpin like cursor,which is projected on the picture, the subject isable to indicate the local orientation of the surface(see Figure 5). The subject is asked to adjust thepushpin like he thinks the disk of the pushpin lieson the surface. The orientation is described by theslant and tilt of the surface normal. Slant is thedegree to which the pushpin leans backwards, andtilt is its wind direction like a compass needle. Themouse serves as a tool to position the pushpin.When the subject is ready positioning the pushpinit is indicated by the mouse as well. The pushpin

Figure 5 An example ofdifferent pushpinpositions on a surface

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will now bepositioned the nextpoint on the picture.The positioning isdone on a (normallyinvisible) triangularsnap grid. After theevaluation of thepicture the raw dataof slant and tilt forevery vertex iscomputed into alocal surface normal.For every pair ofvertices a local depthis computed, whilethe final vertexdepth value isestimated by a curvefitting procedureusing a least squarescriterion where themean depth value isset to zero. Now foreach (x,y) value ofthe grid a depth value z can be added and a 3D-reconstruction of the perceived surfacemade.

In this study all images were triangulated and evaluated with the Koenderink method bythe subjects. In this way perceptual data on 60 surfaces was obtained. As an example,Figure 6 shows how the stylistic sketch of car1 was triangulated and how one of thesubjects saw its shape.

4.4 Comparison between tangible shape characteristics and intangibleemotions

After the investigation of the aesthetic feelings and the documentation of the perceivedgeometry the data was compared across the subjects and the stimuli. As an illustrationwe will elaborate on the findings on elegance. On average the subjects felt that theprototypes were less elegant than the sketches. For instance for car4 the rating forelegance drops from 2.0 to 1.5. As an illustration both perceived shapes of this car arepresented in Figure 7. The geometry differs in the sense that the connection between thehood and the windscreen is experienced sharper in the prototypes. This is indicated bythe line drawn along the meshed surfaces. The other cars showed the samecharacteristics so it was concluded that an “edgy” surface as experienced in theprototypes gives a less elegant object. Furthermore, it was found that sketches wereexperienced as more stretched or directed. This was indicated by the occurrence ofpronounced long shapes in the surface meshes.

Figure 6 Triangulated image and 3D reconstructed surface forone of the stimuli.

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The previous example shows thatthere must exist a relation betweenexpression and perceived geometry(question a). The method used issystematic but more data is neededto generalize conclusions. Thejudgment of shape characteristicswas based on subjective qualitieslike: the surface is stretched or thesurface is edgy. However, it seemsto be possible to find some handlesto cope with these subjectivequalities. An interesting futureissue is to look at a comparison ofthe perceived shape of the imageof the product prototype and theactual geometry which of course isknown. In this way we can extendour understanding of the aestheticstowards the space of designvariables (Figure 8).

This study does not answer thesecond question (b) becausedifferent designed geometries to

measure the intended aesthetics were not used like in the study in chapter 3. Adifference in the expressive judgment between the sketches and the prototype (questionc) was observed. Geometry tends to be more edgy later on in the process. One of theexplanations in this specific field is the enormous amount if engineering restrictions thathas to be taken into account during the product development process. Packagingrestrictions and manufacturing issues might form a major cause for the change ingeometry. This can also be seen in the expressive term whereas the functionality showsto be higher in the final prototype in which the functional requirements are integrated inthe design. Finally, some shape interpretation differences between both groups ofdesigners (question d) were seen. Especially, the use of reflections in stylistic drawings,which are used to exaggerate certain shape intentions, lead to more articulated surfacesfor the automotive designers.

In the context of this paper we have seen that several efforts already have been made toinvestigate the link between aesthetic and product characteristics. Referring to Figure 8we can position the research presented in chapter 3 as an approach to investigate thecomplete “loop” of understanding how aesthetic evokes feeling and how to designaesthetically pleasing products. This was illustrated using a phenomenological approach.Chapter 4 elaborates on the upper path only in Figure 8 of understanding how aestheticevokes feeling. Nevertheless, in the described research a systematic scientific methodwas used giving us more formal information about the phenomena than the extendedexpressive profiles as used in the study of Desmet. The next chapter will build on these

Figure 7 The perceived shapes of car4 for thesketch and the product.

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experiences and propose a general methodology for linking aesthetic characteristics andshape.

5 A methodology for unifying aesthetics and design

5.1 The need for knowledge intensive support of aesthetic design

Although its importance is well known, formalized and systematized manipulation ofaesthetic concepts is almost in its infancy. In commercialized CACD/CAD systems,support of aesthetics stopped at the level of fast shape prototyping and of expressingvisual intent by manipulation of shape (surface) features. What we miss is andprocessing the aesthetics related design knowledge. Present feature technology is closelylinked to conventional geometric modeling engines, therefore, involving aestheticsknowledge explicitly is very difficult, if not impossible.

The most intrinsic issue of development of a design for aesthetics methodology is howto implement the mapping between the space of aesthetic features and the space ofshape-induced geometric parameters. The relationship between aesthetic appreciationand design is rather vague. It also raises philosophical issues about the relation betweenhuman beings and artefacts they create. We accepted the fact that any aestheticjudgement is necessarily a potential feature of the way in which we attend to objects(Palmer and Dodson, 1996). Thus the correspondence between the elements (groups) ofthe two spaces is vague and is not straightforward. It can be apprehended through theinvolvement of psychological aspects only and it is strongly influenced by cultural,personal, sociological, etc. facts.

Aesthetics is a simultaneous communication of meaning and beauty. Therefore, thetheory of design for aesthetics has to explain how meaning and beauty arecommunicated by a particular manifestation of an objects. The principal medium ofcommunication is the shape of an object, but the colour, texture, material and othervisual properties play also important role. Actually the totality of these object propertiesmakes impression on us and exerts emotion. This fact makes the task complicated. Thatis, aesthetics of objects has to be addressed individually.

5.2. The fundamental concept: the analogy of informationcommunication

Prior to the development of a computer-supported design for aesthetics methodology wehave to model this specificcommunication process. Onthe one hand, because theprinciples of generalinformation communicationare rather well known and, onthe other hand, since ananalogy with communicationof aesthetic intent can beobserved, in finding out theknowledge processingfundamentals of the needed

Space of aestheticcharacteristics

Space of designvariables

Understandinghow aesthetic

evokes feelings

Designingaesthetically

pleasing products

{ F }1

{ F }2

{ F }3

{ F }4 { V }

1

{ V }2

{ V }3

{ V }4

Figure 8 The problem of two ways mapping

16

methodology we can rely on the theory of communication in information technology. Incommunication of information the semantic content is carried by digital/analoguesignals. In communication aesthetics the meaning is delivered by shape properties. Thisinformation is however implicit and the meaning cannot be completely separated fromits interpretation. Consequently, aesthetic designers first have to understand how shapeevokes feeling in the case of a particular product and a cluster of consumers. It meansthat, contrary to the one directional methodology of conventional design for Xtechniques, design for aesthetic manifests in a closing loop (Figure 8). Our investigationrevealed that the loop unifying aesthetics and design, is formed by the linked activitiesof understanding how a particular shape of a given product evokes feelings, and whatdesigners should do to be able to communicate an aesthetic message and achieveemotional satisfaction and attraction to certain shapes.

From the theory of communication it is well-known that four levels can be identified inthe information transmission process. These are (a) statistical, (b) syntactical, (c)semantical and (d) pragmatic level. None of the mentioned levels is able to provideeffective communication in itself. On the statistical level of communication, the amount,magnitude and distribution of physical signals are dealt with. On the syntactical level thepatterns of the signals are extracted and interpreted. On the semantic level the meaningof the patterns of signals is reasoned out. Finally, on the pragmatic level the context andthe goal of the communication are interpreted. In addition, recent studies circumscribe afifth level that is orientated to explain what the motivation and the behavioralbackground of the sender was. Although not explored exhaustively, the fifth level, thatis called apobethical, might open up new dimensions in understanding the deepestknowledge related to communication of aesthetic properties.

5.3. Understanding aesthetics for shape design

The analogy of communication facilitates mapping between the space of aestheticfeatures (evoked feelings) and shape parameters. In the looping process formed by theactivities that are targeted to explore and understand why and how does an object evokefeelings and by those that are to design a product achieving a conceived aestheticimpression, similar communication levels. The contents of the levels however differdepending on which side of the loop they refer to. Figure 9 shows the communication-

Process of understanding how aesthetics evokes feelings

{ F }1

{ F }2

{ F }3

{ F }4

Semanticallevel

Syntacticallevel

Statisticallevel

Pragmaticlevel

Experiment withtypical objects

Clustering objectsbased on feelings

Exploring commoncharacteristics

Identifying shapecharacteristics

Understanding theinfluence of shape

Space of

characteristicsaesthetic { V }

1

{ V }2

{ V }3

{ V }4

Space of

variablesdesign

Figure 9 The communication model of understanding how aesthetics interactswith people

17

based model of understanding how aesthetics interacts with people. The communicationanalogy also supports setting up an experimental process to explore and systematize therelated knowledge.

In order to understand how meaning and beauty interacts with people an experimentalsub-process is executed. A representative set of objects of different observable aestheticcharacteristics is put together. Potential consumers/users are asked to select thoseobjects that, due to their aesthetically similar or resembling shapes, can be sorted intothe same cluster. Only a fuzzy clustering is possible since the objects can be sorted intomore than one cluster based on their aesthetic characters of different dominance. Fuzzyclustering is one of the conceived advanced modeling techniques that are useful for dataclassification and pattern recognition problems. It is an iterative technique that seeks tocompute a membership function that indicates to what degree a data point belongs to agiven cluster. It can be used either for data analysis or aesthetics pattern recognition.

The activities mentioned above are related to the statistical level of communication. Thenext step is the exploration and naming of aesthetic characteristics common for theobjects in a cluster. The users are asked to circumscribe the aesthetic properties theyobserved and recognized as well as to depict the feelings the objects individually evokedin them. The verbal descriptions of the observations, impressions and the feelings bringus to the syntactic level of communication. The specifications of the correspondingaesthetic properties form the perceptual part of the vocabulary of design for aesthetics.The specifications are based on linguistic variables that express a kind of commonunderstanding of the aesthetic characteristics.

The semantical level of communication relates the explored aesthetic characteristics tothe shapes of objects and analyses the correspondences. Only the most dominatingaesthetic characteristics are taken into consideration and it is investigated which shapefeatures might result in that particular characteristics. This is repeated for all of theclusters in the same way with the same objective. This way clues are formed for thepossible relationship. Since the shape is influenced by the less dominant aestheticcharacteristics too, formulation of relations cannot be deterministic. On pragmatic levelthe adequacy of matching the aesthetic characteristics with global and local shapeproperties is tested. The shape properties are modified and the potential users are askedto judge whether the previously recognised aesthetic characteristics become stronger orweaker, or remain intact. It is also investigated if any of the previously less dominatingcharacteristics change significantly. Although the aesthetic factors were implicitlytreated, we can conclude a synthesized knowledge about the influence of the shape forthe designers. This instituted knowledge can be formalized in the knowledge base of acomputer-aided design for aesthetics system.

5.4. Aesthetics stimulated by shape design

Above we described the explorative sub-process that is orientated to understand howshape influences feelings. Figure 10 shows the creative part of the looping process thatrelates to systematically designing aesthetically pleasing products. In principle it isdirected from the space of design variables to the space of aesthetic characteristics. As astarting step, designers should generate an initial shape that fulfils functionalrequirements. The initial shape is depicted from geometric, topological andmorphological point of view. This specification of the initial shape belongs to the

18

statistical level of communication. Then the shape is globally crystallised to come upwith the needed observable shape characteristics (e.g., type, extent, proportions,morphological articulation, distortion, number of components, etc.).

Global shaping leads us to the syntactical level of communication since it furtherspecifies the meaning but it does not make it complete. On this level of communicationadditional design aspects (e.g., material, colour, texture, brandmarks) are also taken intoconsideration. On the semantical level, the shape designing process manipulates localproperties in order to incorporate subject related aspects (e.g.,, style, fashion, humanpreferences, etc.). As a part of the semantical communication the additional designaspects are also manipulated to achieve emotional impacts. On the pragmatic levelusers’/customers’ opinions are collected to measure satisfaction and to further improveaesthetic impressiveness. This advance measuring of the evoked feelings howeverbacktrack us to the explorative sub-process which aspire to explain "feeling basedresponses" to products.

Our initial experiments and tests have shown that the information communicationanalogy helps in understanding the core problem addressed in this paper and supportsthe elaboration of a quasi-formalized methodology that can be used in the future as thebase of tool development to model shapes which a certain aesthetic intent.

5.5 Toward a formalism for the mapping between shape parametersand aesthetic characteristics

As mentioned in section 5.1, the correspondence between the space of shape-inducedgeometric parameters and the space of aesthetic features is vague. However, we arguedthat an implementation of a mapping between the two spaces is a prerequisite for anymethodology of design for aesthetics. The development of such a methodology involves(1) obtaining the mapping and (2) employing the mapping as part of the methodology.Idealistically the mapping specifies, for an expressed aesthetic intent, those values ofshape parameters as to achieve a design model conform the intention. We will introducea set-theoretic description of such mapping in order to investigate the feasibility of thesteps (1) and (2) mentioned. A set-theoretical formalism seems very appropriate to

Process of designing aesthetically pleasing products

{ F }1

{ F }2

{ F }3

{ F }4

Semanticallevel

Syntacticallevel

Statisticallevel

Pragmaticlevel

user experimentsContolling by

product imageFinishing the

shape featuresDesigning local

shape featuresDesigning global

functioning shapeDesigning of the

Space of

characteristicsaesthetic { V }

1

{ V }2

{ V }3

{ V }4

Space of

variablesdesign

Figure 10 The communication model of how aesthetics can be expressed troughdesign

19

clarify such fundamental issues as object identity, context specification and relationshipbetween objects.

The two aforementioned spaces will be referred to as the space S of shape variables andthe space A of aesthetic variables. We assume that at some point in time, a finite numberof shape variables si and aesthetic variables ai are relevant. These variables arecontained in the sets {s1,s2, …, sm} and {a1, a2, …, an} where each of the elementsspecifies (1) a type and (2) a value domain. We give three examples of possible shapevariables:

• s1 has type “height” and value domain ℜ +,

• s2 has type “angle between arm and body” and value domain {“zero”, “sharp”,“wide”}

• s3 has type “y-co-ordinate of the 23d control point” and its value domain is ℜ .

is a fundamental issue to be discussed later. The value domains may be continuous,discrete, ordinal, nominal or even arbitrary. The types are assumed to capture sufficientsemantics. As is common in verbal communication, a label such as “height” conveys allnecessary information in some context. The proposed formalism, however, will mainlybe based on the value domains of the variables.

Two examples of aesthetic variables are,

• a1 has type “harmony” and value domain {-2, -1, 0, 1, 2}.

• a2 has type “emotionality” and value domain {“sad”, “angry”, “joyful”, “serene”}

We define the space S as the Cartesian product of the domains of s1…sm. Similarly, A isthe Cartesian product of the domains from the shape variables. Let d denote adescription of a design object; d is in general a member of some Universe of DiscourseD, where we assume that d ∈ D is accepted, by some people at some point in time, asrepresenting the design object at hand. We are interested in the relation between a givendesign model d and points in S and A, i.e. we wish to determine the subsets RS ⊆ D × Sand RA ⊆ D × A, where × denotes the Cartesian product. These RS and RA specify whichproperties (in terms of si and aj) apply to a given d and, conversely, which objects in Dcomply to specified tuples of S and A. It is useful to consider whether or not each of thefollowing statements apply to the relation RS:

1. For given d ∈ D there exists no s ∈ S such that (d, s) ∈ RS (S is incomplete)

2. For given d ∈ D there exists exactly one s ∈ S such that (d, s) ∈ RS (S is unique)

3. For given d ∈ D there exist multiple s ∈ S such that (d, s) ∈ RS (S is ambiguous)

4. For given s ∈ S there exists no d ∈ D such that (d, s) ∈ RS (S is too rich, or D toopoor)

5. For given s ∈ S there exists exactly one d ∈ D such that (d, s) ∈ RS (S isdeterministic)

6. For given s ∈ S there exist multiple d ∈ D such that (d, s) ∈ RS (S isnondeterministic)

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The same evaluation can be made for relationRA.

A parametric modeling system typically has RS

with property 5 for all s ∈ S. However,property 2 needs not to apply; it is commonthat a given model is achievable usingdifferent values for the variables. If a designer(or a system) fails to produce a model for aparticular m-tuple of S then RS has property 4.Let us assume, for a while, that RS hasproperty 2 for all d ∈ D and additionally hasproperty 5 for all s ∈ S, i.e. there RS is abijective function FS : S → D. Similarly, let usassume the existence of a surjective (butpossibly not injective) function FA : A → D,acting as a candidate relation RA. The mapping

f: A → S from aesthetic variables to shape variables can then be defined as

f(a1,…,an) = (FS)-1 °FA(a1,…,an) (1)

(see Figure 11). For convenience of notation we write a point in A as the n-tuple (a1,…,

an), where ai is understood to denote a value, rather than a type and a value. Similarly, apoint in S is written in the form (s1,…, sm). The interpretation of equation (1) is asfollows. For any instance of the aesthetic variables we can identify some design model,which, in turn, is specified by a unique instance of the shape variables. This procedureobviously has a very restricted extent. However, it is possible to relax some of therestrictions as we will show later. In general, for given f, each of the shape variables si

defined by f(a1,…,an) = (s1,…,sm), is a function of all aesthetic variables, hence weshould write

f(a1,…,an) = (f1(a1,…,an), … , fm(a1,…,an))

First we examine what the implications would be of the mapping f defined in equation(1). These include:

1. Each point in S-space is associated to exactly one design model in D,

2. Each point in A is associated to exactly one design model in D,

3. Each design model in D has exactly one associated point in S,

4. Some design models in D may have no associated point in A,

5. If two design models in D are different, so will their associated points in S,

6. If two design models in D are different, their associated points in A may be bothnonexistent, one may be nonexistent, or both may be existent and be the same ordifferent,

7. Each point in A maps (using f) to one point in S,

8. Two points in A may map to the same point in S,

D

S A

FS FA

f

•

••

Figure 11 In the most simplesituation the mapping f :A→S is equivalent to (FS)-

1° FA.

21

9. There may be points in S that cannot be a result of the map from A.

The limitation expressed by items 4 and 9 reflect the scope of equation (1) which doesnot deal with design models that cannot be prescribed by aesthetic variables. Indeed theprimary interest is the capability of f to be map from A to (not necessarily onto) S; thisleads to

Observation 1: A mapping f from A to S needs not to be one-to-one.

This implies that, despite the restrictions we introduced, the specifications using termsin one space are not equivalent to specifications in terms of the other space. Anotherimportant observations is as follows:

Observation 2: The specification of a mapping f from A to S involves the existence ofat least one member d∈ D.

This may be not obvious from equation (1), where the dependence of f on d ∈ D isimplicitly defined by the relationship RA between A and D. Observation 2 suggests thatit is unfeasible to define a dependence relation between, for example, “sharpness” and“agressiveness” without reference to at least one object. It is important to verify whetheror not these observations depend on the restrictions that we introduced for equation (1).Before doing so we consider the special case, where the shape variables and theaesthetic variables form real vector spaces, i.e. S = ℜ m and A = ℜ n. For this case wedefine the Jacobian matrix Jf of the map f : ℜ n → ℜ m as the m×n matrix of the firstderivatives of f, i.e.:

Jf(a1,…,an)ij = ∂/∂aj fi(a1,…,an).

The Jacobian matrix is commonly used to analyze maps between two vector spaces thatare both domains to represent kinematic systems (Latombe, J.-C., 1991). The entry (i, j)of Jf specifies how much variable sj changes due to changes of variable aj. In accordanceto observation 2, this change is dependent on the point in A where it is evaluated. Inkinematic analysis the function f is sometimes reconstructed from measurements of itsJacobian matrix, which is a principle that may carry over to our field of interest.

5.6 Obtaining a map f and applying it to design for aesthetics

To specify a map f we need to know the structure of the spaces S and A, i.e. the typesand the value domains of their variables must be defined. Let us review what has beenachieved, in this respect, in the study reported in chapter 3. In section 3.2 the types“intensity” and “pleasantness”, among others, were introduced and their value domainsspecified in figure 2. Subjects were confronted with eight existing mobile phones inorder to determine design model-dependent values of the variables. This can be regardedas an attempt to establish the relation RA between the spaces D and A (if we considerintensity and pleasantness to be aesthetic variables). This relation was found to besubject-dependent. In section 3.3 variables of S were correlated to elements from D,which can be regarded as a search for the relation RS. Next, a positive correlationbetween some of the si and aj was reported based on statistics induced by stimuli, i.e.elements of D. Finally, this correlation was applied to create new elements of D (i.e.new designs) as follows. If it was found that for relatively many elements in D a valueα i of variable ai correlated with value σj of variable sj, then it was hypothesized that a

22

new q ∈ D for which si = σj will also have ai = α i. This expectation was then verified, asdescribed in chapter 3. The aforementioned positive correlation can be regarded as anindication of the existence of a map f, although the data allow, at most, the specificationof a relation between S and A, rather than a mapping. This interpretation of the report inchapter 3, as well as more general considerations raise several issues:

1. The choice of types of variables ai and si seems to be inspired by the design objectsdi at hand. This limits the range of any relationship RA and RS to a particular subsetof D, which may be too restrictive if the relations are to support design foraesthetics.

2. It is important to distinguish between the type and the value of variables; in table1the shape characteristics seem a mixture of types and values.

3. The relationships RA and RS should be based on empirical data. Subject dependencecan be incorporated by either introducing subject-specific (or subject category-specific) relations, or by including ome subject-dependent weighting function.

4. Measuring RA and RS is not a well-defined process. The assignment of values to theshape and aesthetic variables is mostly based on panel responses and is unlikely tobe a reproducible action. This instability has repercussions on the mapping f.

To gain stability (c.f. issues 2 and 3) one could refer to subsets of D rather thanindividual elements when establishing the relationships RA and RS. Indeed, when aspecific design di ∈ D empirically relates to some si ∈ S then this may be true for someneighborhood of di.. This would require D to have a topology. Conversely, a topologyon D could be based on a classification of D, where a class is formed by elementsrelating to the same point in S (or A). Another approach is to not attempt to directlyobtain RA and RS, but to measure their changes with respect to changes in the space D.For example, based on panel responses it seems easier to detect that a certain edge getssharper, than to obtain agreement that a particular edge is “moderately sharp”. This is inanalogy to measuring the Jacobian matrix of a robot in attempt to reconstruct themapping from configuration space to Eucledian space. Obviously, the notion of“differentiation” of shape (or aesthetic) variables with respect to d requires continuousor quasi-continuous properties of the involved spaces. Design for aesthetics could thenbe supported if the aesthetic intent is specified as a modification (∆a1,…,∆an) relativesome reference design di. Then, if the restrictions for equation (1) apply, the candidatenew design di+1 is obtained by changing the shape variables as follows

(∆s1,…, ∆sm) = (∆a1 Jf(a1,…, an)1,1,…., ∆an Jf(a1,…, an)1,n) + …

… + (∆a1 Jf(a1,…, an)m,1,…., ∆an Jf(a1,…, an)m,n),

where (a1,…,am) ∈ A represent the aesthetic variables’ values for di, i.e. FA(a1,…,an)=di.The new di+1 is

di+1=FS(s1 + ∆s1,…,sm + ∆sm).

To gain detailed insight in the nature of the mapping f (either the one according toequation (1) or a less restricted relation), we recommend to perform initial experiments

23

using relatively simple spaces S, A and D, primary to test the stability of valueassignment to the variables.

6. Discussion and conclusions

There exist uncertainties about the scientific understanding of how aesthetics and shapedesign meet. The terms used to describe aesthetics are rather subjective and have nodirect relationship to the characteristics of the shape as a whole, or as a composition ofits parts. Aesthetics is conveyed by the shape which is however only one aspects ofmaterialization of the product. When aesthetic effect is considered as a totality, otheraspects like colors, texture, patterns, etc. are to be taken into account too. In this paperthe authors attack three issues of design for aesthetics: (a) to understand the way howproducts evoke feeling, (b) to link product characteristics to aesthetic factors, and (c) todevelop a methodology that enables us to provide better computer support to design fordesign for aesthetics.

Several authors claimed that a product gives rise to sensory stimulus, i.e. perception,that in turn brings about feeling-based responses. Therefore, dealing with aesthetics hasa lot to do with the psychology of inspired emotions. First of all, aesthetics of a productattracts the user in the shops, advertisements and magazines. But the aesthetics alsoinfluences the relation of the user to the product when it is in use. It means thatexplanation of appreciation need simultaneous consideration of the human behavior as aconsumer and a user.

While a designed product can trigger definite aesthetic responses to observers, it is noteasy to relate these responses to the characteristics of the product. In most of the time,designers work instinctively. They spontaneously apply their skills and knowledge andjudge their successfulness in incorporating aesthetic intends based on their ownemotions. Efforts have been made to explore and explain the relation between aestheticintent and design properties, forming a loop between users and designers. However, themethods they use are strongly dependent on the product, people, objectives and situationand are not fully scientific. On the contrary to these phenomenological approaches,some work tried to apply formal approaches and scientifically sound methods. Due tothe lack of some of the knowledge needed, but also to the complexity issues, they havebeen compelled to treat the problem either from the aspect of user-product, or the aspectof designer-product relationship. By giving up the desire to be comprehensive and byfocusing particular aspects only, these systematic approaches have not been able todeliver the requested methodological framework for design for aesthetics. The papergives insights to two studies that supports these statements.

In order to create a closed loop between designers and users, or users and designers, andto unify aesthetics and designing, the paper proposes a framework which utilize theanalogy of information communication. The communication loop of aesthetic propertiesdivides into two parts: one is an explorative sub-process that is orientated to understandhow shape invokes feeling, the other is a creative sub-process that relates tosystematically designing aesthetically pleasing products. Although the rich diversity ofaesthetic characteristics makes it impossible to produce categories that cater for alltastes and styles, it is nevertheless feasible to identify classes that cover the essence ofmore commonly accepted aesthetic intents and leave out individualistic differences that

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are more extreme. The problem of delivering aesthetic intent is decomposed ontostatistical, syntactical, semantical and pragmatic levels of communication. Our initialexperiments and tests have shown that the information communication analogy helpsunderstanding the core problem of design for aesthetic and supports the elaboration of aquasi-formalized methodology that serves well as a base of computer tool development.

The implementation of a more formalized design for aesthetics methodology arises twotechnical issues: (1) obtaining the mapping procedure, and (2) employing the mappingas part of the methodology. We are developing a set-theoretic approach for the computersupported mapping of aesthetic characteristics to shape characteristics. To gain detailedinsight in the nature of the mapping f we are going to perform further experiments andto test the stability of value assignment to the variables.

Acknowledgment

The authors wish to thank Pieter Desmet for his support to elaborate this paper. CeesOverbeeke was so kind to provide the information on the INSTANCE project(BriteEuRam no.3, project 95/2151). The research work reported in this paper relates tothe ICA research project of the Sub-Faculty of Industrial design Engineering of the DelftUniversity of Technology.

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