I am sitting in the train and opposite to me a couple is reading the newspaper. Every once in a while one of them looks up, checking me and the other passengers out. We are now passing through a tunnel and I can see myself reflected in the window. I see my hair could use a brushing after the rush I was in when catching the train. I refrain from any action though, as I do not dare show any concern for my looks so blatantly in front of other people. I wish I had taken that single seat that was empty when entering the train; at least it would have given me some privacy. Although I feel uncomfortable being so sweaty, I am happy I made it, thanks to that gentleman who helped me out with my bicycle. The bicycle rack on the ground floor at the train station was packed, so I had to lift my bike in one of the upper racks. This is a heavy task, and with a bag on each shoulder I probably looked quite helpless, compelling this friendly (and tall) guy to help me out. While recalling this moment, my thoughts are suddenly interrupted by the voice of the conductor asking to check whether I have validated my public transport pass. I instantly feel my blood pumping through my body again and my body temperature rises significantly. ‘Did I forget to validate it?’ I can’t remember, and I reluctantly place my wallet under his scanning device. ‘Ok. Have a pleasant journey.’ What a relief. Apparently validating my pass has become an ingrained habit by now. As the conductor is checking the passes of the couple opposite me, I remember I wanted to ask him which platform I need to go to for the next leg of my journey. I try to catch his attention, but he is moving away quickly. I decide to look for the platform number on my iPhone using the Railway app. When I find out that it is the platform opposite of the platform my train will arrive at, I finally calm down. Now I can fully devote myself to my writing. The things we use, like our furniture, iPhone apps, or the transportation services we take to get to our destination all play a significant role in the way we live our lives. Often without our being aware of it, the designed environment affects how we act in and experience our world, by making certain behavioural options easier, more attractive, or more common than others. The simple fact that some seats in the train are positioned opposite each other while others are positioned sequentially affects how people behave. Sitting face-to-face probably decreases nose picking and increases small talk. Seating orientation plays a crucial role in the behaviour we display, as illustrated in the example above, where it discouraged me from redoing my hair. And likewise, the design of the bicycle rack described evokes specific social behaviours. Because the upper-rack system is so incredibly user- unfriendly, it actually provides the ideal opportunity for men to put their physical superiority to use and show politeness toward women. And because in many Western societies we tend to rule out any gender inequality, such acts of politeness may be refreshing at times. Additionally, the anecdote above demonstrates how my iPhone provides superb support in planning and managing my journey, but consequently decreases my motivation to socially interact with the conductor or other passengers. Since every detail of my train journey is ‘in the cloud’ and can be retrieved by my iPhone, any interpersonal interaction about timetables or train lines becomes redundant. Because talking to a conductor–a person I do not know–in front of other people–whom I do not know either–sets the perfect scene for me to make a fool of myself, the decision to keep silent is easily made. The chairs in the train, the bicycle rack, and the Railway app have all affected my behaviour and that of others, largely without us being aware of it and probably without any deliberate intention by the designers. Aim of the Thesis The research in this thesis investigates the implicit and often unintended influence of design on human behaviour, for the purpose of designing it. Designers need this knowledge to enable them to take responsibility for the behavioural and social consequences of their designs, as not all of these may be desirable (neither from a user nor from a social perspective). More central to the thesis however, is the assumption that this type of behavioural influence is unique to design in comparison to other interventions that aim to change behaviour, like policies and campaigns. Since many social problems we are facing (e.g. obesity, the depletion of resources, intercultural tensions, or cybercrime) require behavioural change from people to be addressed effectively, design can offer elegant and effective facilitators of such changes. The thesis consists of three parts to explore, support, and test this social design activity. Part 1 draws from a range of theories originating from various disciplines to explain the implicit influence of design. By consolidating these disparate theories, the instrumental value of the theories in realizing desired social change through design is discussed. Emphasis is placed on how people may experience design that is behaviour influencing, and how to consider what type of influence will be both appropriate and effective in attaining a specific social goal. Part 2 develops supportive elements (i.e., a method plus additional techniques) that designers can use to deliberately design products or services that obtain a predefined social effect. We closely examine three design projects in which an initial version of this methodology is used, and we discuss to what extent these supportive elements for designers have increased (social) design performance. The concept designs developed in these projects are examined by social experts, leading to insights regarding both the value and the ‘working principles’ of the designs. Part 3 compares design to more common interventions that seek to stimulate pro-social behaviour, such as signs or text. We expected that design’s implicit influence would be responsible for its behavioural effects. In a field experiment conducted in a school canteen, we tested this hypothesis by comparing implicit influence with explicit influence in changing behaviour, in addition to comparing two types of interventions, i.e., product and text. The studies reported were conducted to gain understanding of how to facilitate the design of original products and services that engender desirable social effects. To stimulate these effects, the designer is encouraged to deliberately direct the implicit influence products unavoidably have. Therefore, the thesis has a clear design perspective, intended to deliver actionable insights for designers. Social Problems, Behaviour & Design In order to conceptualize the implicit role design plays in the social realm, Chapter 1 explains how existing products have contributed to many of the social problems we are currently facing by implicitly affecting behaviour. Human beings are social by nature. We have lived in groups since the dawn of our existence, and our individual position in relation to the group is therefore inherent to being human. This means that since the beginning of our collective existence we have always been confronted–explicitly or implicitly–with situations in which we have to make the decision whether to act in favour of the group or in favour of ourselves. Do I share my banana, or do I eat it alone? Today, this is no different, save for the fact that we have established societies with millions of people living together. The wellbeing of a group so large is no longer experienced as closely related to personal wellbeing. Many people may consider our changing climate a problem, but few experience this as a personal problem upon which one should act immediately. Moreover, tackling such global or social problems requires willpower, because it often means giving up comfort, flexibility or efficiency. More abstractly, collective concerns (like sustainability) are not always internalized by the individual, and are not always in line with personal concerns (such as seeking comfort and convenience). This in itself may be a static fact, but the very fact that we have designed an environment so well adapted to our personal concerns means that we sometimes invite behaviours that are detrimental to all of us in the long term. My car offers me a convenient and comfortable means of transport, but we know by now that the emissions produced by it negatively influence climate change in the long term. Many products and services implicitly advocate acting in ways that benefit oneself rather than society. The question therefore arises: how can we design implicit influence that helps users act in favour of society more often? Part 1 – Understanding The Influence of Design on Human Behaviour Scholars from a variety of disciplines have studied the influence of products and services on people’s actions. A theoretical comparison of six theories underlying this phenomenon shows that product influence can be studied and understood either analytically or synthetically. Behaviour– when affected by design–can be understood as the result of the interaction between user and product (using an analytic approach), or it can be understood as part of a larger context in which other cultural, contextual, and social factors that play a role in shaping this behaviour are examined (using a synthetic approach). We illustrate that the more holistic theories of the latter support designers understanding of what behaviour is best to change; in other words: ‘where to intervene.’ Analytical theories may then deliver the knowledge regarding how to actually embody this influence in the design. Although these theories are explanatory and therefore supportive to design activity, little insight is given into the experiential side of product influence. How do people perceive and experience things that affect their behaviour? To answer this question, we analysed sixty-eight products that were designed to have, or happened to have, an effect on behaviour. This analysis revealed that two dimensions define the type of influence based on user experience: the salience of influence and the force of influence. Products can be more or less explicit and more or less forceful in stimulating behaviour; these respectively correlate to the user’s awareness of the influence and having the feeling that one’s personal freedom is being limited. Combined, these two dimensions identify four types of influence: coercive, persuasive, seductive and decisive influence. We provide arguments that support the idea that implicit influence is most appropriate and effective at counteracting social problems in which collective concerns are in conflict with personal concerns. To support the design of products and services with predefined social effects, the insights gained about the implicit influence of design were consolidated into a conceptual framework. The value of this framework is illustrated here through a discussion of six social design projects. We explain how the framework relates to three important steps of the design process: 1) the designer’s approach to deciding which behaviour to change, 2) the designer’s understanding of the relationship between users’ personal and collective concerns, and 3) designing a specific type of influence. Part 2 - Designing Products and Services with Desired Social Implications Our framework of product influence in the social realm was integrated into the Vision in Product design method (ViP). This approach, dubbed the Social Implication Design method (SID), stimulates the designer to study the social phenomenon he or she intends to work with, e.g., social ties, emancipation or safety, and recognize relevant and influential (social, cultural, demographical) factors that affect the behaviour currently being displayed. When deciding what behavioural change to aim for, he or she is encouraged to adopt a social perspective and thus incorporate collective concerns. Next, the designer is asked to switch to a user perspective, and consider personal concerns to be addressed by the eventual design that might make the behavioural change meaningful to the user. The designer is encouraged to reflect upon and build an argument for what type of influence is most appropriate and effective, based on the relationship between individual and collective concerns. Three graduate students applied the SID method in their social design projects. A close examination of their design performance, including an evaluation of the results by social experts, shows that the method appears to support the understanding, consideration, design, and communication of the social implications intended by their designs. Feedback from the experts revealed that effectiveness was mainly ascribed to the implicit power of the design. Designs that were considered most effective by the panel of experts were those that adequately addressed a separate, personal concern; this was perceived as a powerful component of a design’s overall ability to evoke the desired social behaviour. These results underscore our assumption that the method supports the design of implicit influence to bring about a desired social impact. Yet, the extent to which this implicit influence might eventually engender behavioural change in a real-life setting has not (yet) been studied. Although presumably effective, an important drawback of the method is that it appears to demand somewhat artificial and elaborate ways of working. The proposed sequence of activities, i.e., adopting a social perspective to define the desired behaviour first, then taking a user perspective to define how to affect it, did not fit with the integrative thinking many designers adopt. Based on this, the method evolved into a tool to help designers to adopt both these perspectives simultaneously during the design process. Part 3 - Comparing Design to More Common Types of Intervention We conducted an experiment to test our assumption that the implicit character of the influence of design may be particularly effective for counteracting social problems. Four separate interventions discouraging littering were carried out in a school canteen. These interventions varied both in terms of the salience of their influence, i.e., either implicit or explicit, and their type, i.e., either a text or a product. Each of the four interventions was deployed in the canteen for one working week (M-F), and their effectiveness was measured by the amount of garbage left behind. An analysis of the results showed that the type of intervention interacts with the salience of influence. In other words, when using text, it seems that being explicit in influence is more effective than being implicit, while the reverse holds true for products. When a product is designed to affect behaviour that results in desired social impact, it seems implicit influence is more effective than explicit influence. Although this interaction effect is significant, the implications of these findings carry with them a certain degree of reserve. The fact that none of the interventions appeared significantly effective at stimulating people to throw away their garbage in comparison to the control condition is remarkable. We explain that the context of the experiment (habitual behaviour, young target group, and passive instead of active littering) in relation to the high aims of the experiment (practical and academic) complicated the set-up of the experiment. We discuss the limited explanatory power of the concept ‘salience of influence’ in understanding behaviour change, and argue that the concept may be valuable mostly to designers. In aiming for influence that remains unnoticed, it is suggested that designers understand how fundamental human and/or personal concerns may be triggered by design rather than ‘forcing’ people to internalize collective concerns. General Discussion The three parts in this thesis contribute respectively to design philosophy, design methodology, and design theory. The first part extends our thinking about the role design plays in shaping human behaviour, and more specifically its often unintended and unnoticed role. We carefully build a framework that explains this implicit influence of design as it pertains to the social realm. In doing so, we bring various existing perspectives together and complement these with a user perspective. We discuss how the framework relates to the act of designing. In fact, the Part on1 builds up to two hypotheses that have been sequentially tested in Parts 2 and 3 (p.6). The second part explains the development of a design methodology to support the design of implicit influence that engenders a predefined social effect. This part presents an elaborate evaluation of an initial design method and thereby advances 1) the academic discussion around the origin and purpose of design methods, and 2) our knowledge of how to assess their effectiveness. The research approach taken, a multiple-case study and an expert study with the use of narratives, expands our understanding of design method testing. We illustrate a careful approach in which data from multiple sources are correlated to indications of good design performance. Our results underscore our assumption that the design method supports the design of implicit influence. However, the usability of the method appeared rather poor, for which we decided to replace the method by a set of tools the designer may incorporate within any design method. The main change in doing so is that instead of switching from a ‘social’ to a ‘user’ perspective halfway through the project, the designer is encouraged to adopt these two perspectives simultaneously throughout the project. The last part reports extensively on the set-up of a field experiment to test our assumption that it is the implicit influence of design that is most effective in counteracting social problems. Although our experiment presents an interaction effect, its main contribution lies in examining both the set-up and results of the experiment. We conclude that the experiment wished to study too much with too little means. As design researchers, we are often both concerned with building design theory and with the implications of our findings for design practice. Yet developing interventions that are effective at fostering a behavioural effect requires a different approach than developing interventions to test assumptions that build on design theory. Based on our experiment and its findings, we discuss the value of design theory, and argue that design theory, as a theory of effective embodiment of psychological principles, is a valuable tool to bridge the gap between fundamental and applied social psychology. ‘Salience of influence’ is a difficult phenomenon to comprehend, and a difficult phenomenon to study. Beyond a discussion of its implications for design practice, and an exploration of how social design could position itself in relation to developments in the domains of social innovation and social corporate responsibility programs, we reflect upon the value of this concept in itself. Future study should be carried out to test its explanatory power, i.e., can salience explain behaviour, rather than merely indicating that an underlying psychological principle has been triggered? A subsequent discussion examines how implicit influence may be an indication that an intervention apparently addressed a user’s ‘felt’ concern. By focusing on fundamental, personal concerns, designers overcome the difficulty of estimating levels of user awareness and recognition of the influence of the product-to-be-designed. By considering all the research reported here from this perspective, we recognize how design may resolve, bypass or transform a conflict between personal and collective concerns. Future studies need to be conducted to find out whether this approach to the unintended and hidden influence of design helps to understand and design this influence responsibly and effectively.