The field of Interaction Design is relatively new compared to other well-established fields like maths or physics. Although quantitative research in the field has made it more science-like, we can hardly say it is pure science. Experiments in science should be reproducible and theorems in science can be strictly proved, but this is hardly realised in user research.
IxD – An unmatured field
Another manifestation of an new or un-matured field is that people use different terms to refer to the same thing. In the field of interaction design, people actually speak different dialects of jargons. For example, some people describe what they do as “Interaction Design”, some as “Human Computer Interaction”, some may simple say “User Interface Design”. Well, the last one might be a little bit out of date, since User Interface Design traditionally refer to graphical design. For HCI and IxD, I would say both are interdisciplinary, are umbrella terms and both mean that we design interactive artefacts to support people communicate and interaction in their daily life. Of course, IxD might be a bit larger than HCI, since HCI mainly focus on the design, implementation and evaluation of computing artefacts, while IxD may cover a wider range of products, without limiting itself to computing devices. Actually such examples spread everywhere in our field, and I am not going to talk about all of them. I want to pick up two terms “user experience” and “usability”.
Usability and User Experience
If you were asked to give the aim of Interaction Design (or whatever you call it). You might answer “to enhance positive user experience and reduce negative user experience” or simply “to ensure quality user experience”. You may also answer “to make a product more usable” or “improve its usability”. In fact, each answer is correct in its own right. However, what is user experience? what is usability? Are they referring to the same thing? Does good usability ensure good user experience?
Usability is an older term compared to user experience. It basically means the ease of use of a product. To ensure usability, your system needs to satisfy a set of objective usability goals, which I will be talking about later on. Compared to usability , user experience is more subjetive. Every product that requires user interaction has user experience. It reflects the feelings a user has when use the product. These feelings include the overall feelings of the look-and-feel, engagement etc, they also include feelings when a user e.g. press a button, choose a menu or whatever they interact with the product. They might be happy, astonished or frustrated. All these contributes to the user experience of a product. Of course one cannot design the user experience, because you cannot design how a user would feel your system. One can only design for the user experience, i.e. design the user interface to trigger users’ positive feelings.
Whenever we design a user interface by following interaction design methodologies, we must fulfil a set of usability goals and another set of user experience goals. We cannot say usability goals and user experience goals are mutually exclusive, we would rather say that they have different focus.
What are the usability goals? As I mentioned at the beginning of this article, the field of interaction design is still unmatured, so you will find many principles or theories that are guru-oriented, by which I mean, some pioneers in the field such as Jokob Nielsen, Ben Schneidermann, Donald Norman etc. have their own theories. Although those theories are quite similar to each other, they are not completely the same. I think I am going to write another blog article talking about HCI principles and theories, where you will find a lot of alternative principles proposed by different gurus. The difference between principles and goals is that principles are more focused on “how”, while goals are more focus on “what”. Today I just want to focus on usability goals.
Jokob Nielsen, a Danish usability consultant, is a big name in usability. He defined five components as goals for usability. I call them the LEMES goals, which are five words with L, E, M, E, S as their initials respectively. These words are kinda abstract, so usually interaction designers use these goals by formulating questions for each term. The good thing of these goals is that all dimensions are measurable.
1. Learnability (measured by time to learn)
e.g. How easy is it to learn how to use the product?
2. Efficiency (measured by time/speed to complete the task)
e.g. How efficiently can the users perform their tasks or get things done correctly?
3. Memorability (measured by retention rate)
e.g. Once you learn how to use a product, how easy is it to remember the workflow after not using it for a long while?
4.Errors (measured by error rates)
e.g. How effective can your product prevent users from errors? For example, sometimes a door is designed in a way that it automatically locks when you close it. This is designed with this goal in mind. Of course you can argue that it may cause problems if you happen to forget your keys inside the room. So it actually prevents one error (forget to lock the door), but increase the chance of another error (forget the key at home). Another example is a water boiler, usually such a boiler can be switched off automatically when the water is boiled, this is to prevent you from forgetting to do so.
5. Satisfaction (measured by satisfaction scales)
e.g. How satisfied are the users after using the product?
Yvonne Rogers added three extra goals in her book “Interaction Design”, which are safety, effectiveness and utility. She also removed satisfaction and errors. I understand why she removed satisfaction from usability goals. Satisfaction is subjective, and hard to measure it should be classified into user experience goals. She referred safety as not only protecting users from danger in life, but also from danger in unintended behaviours of the system (errors). So this safety term actually overlaps with Nielsen’s Error goal. By effectiveness, she meant a product should not only be efficient in executing jobs, but also effective in result. For the utility goal, actually she meant a product should provide the right set of functionalities for users to perform the tasks they want.
I think Rogers’ goals and Nielsen’s goals are complementary. Of course one can propose his own goals for usability, but these 8 terms are already useful enough. As I said, these usability goals do not tell you how to ensure usability of a product, it simply tells you that you need to keep these questions in mind when designing a new product, and ask yourself repeatedly if these goals are fulfilled during the design process.
(2)Use Experience Goals
What are the use experience goals? Briefly speaking, they are a set of subjective qualities that reflects how users feel a product, and our goal is to reduce the negative feelings and enhance the positive feelings. According to Yvonne Rogers, some quality aspects are listed as follows (not complete):
Satisfying, Helpful, Fun, Enjoyable, Motivating, Surprising, Emotionally fulfilling
Boring, unpleasant, frustrating, annoying
To measure these feelings of users, one can do Shadowing (a user study method) to observe how users use your product, one can also design questionnaires to ask people’s feeling with the above listed terms with Likert-scales (emotions in opposite direction), such as “Describe your feeling after using the system : Unpleasant 1 2 3 4 5 6 7 Pleasant“. The former method allows you to observe their instant emotions when they are using a product, but it is NOT always feasible and sometimes even impossible. For example, if you want to observe people’s emotion of listening to music while taking a shower. You cannot follow him/her in the bathroom. The latter method allows you to assess the overall feelings of users after using your product. These feelings might not be precise, but much easier to acquire.
Just as the example I gave in the previous paragraph, listening to music while taking shower may be pleasurable. Listening to music while working may be motivated for users. So if you are designing a product, depending on the context of usage, it will result in different user experience. That’s to say, user experience goals are very subjective, not like usability goals, which are just a set of objetive criteria.
Which is more important?
After presenting the differences between usability goals and user experience goals, you may wonder, which are more important when designing user interfaces? My answer goes for the latter ones. Of course, sometimes usability and user experience are overlapping. You ensure one thing, and you inherently have the other one as well. But there are occasions where this does not hold. For example in computer gaming, studies have shown that people love challenges. That being said, you as a designer, can sacrifice usability to make the game harder to control, but this may achieve higher user experience.
In the gaming example, I already showed low usability can achieve high user experience. However, maybe I need to talk about something else, because gaming is kind of “outliers” in interaction design. So, next I am going to talk about recommendation systems.I just want to show why I think user experience can be more important. In many online shopping websites, including Ebay, Taobao, Amazon, also airline websites, they often recommend you products that you may potentially have interests in. Last week I bought an air ticket from easyjet.com for my summer vacation. Before I could enter the payment page, the website recommended me hotels and car rental options as shown in the following picture. (I don’t want to tell you where I am going for my vacation, so I faked the following image by choosing London as my destination) .My question is: why? Why did the airline company offer me options for hotel booking and car rental? Which aforementioned usability goals were the designer trying to achieve?
My answer is : None.
Easyjet provided me with these options for no usability reasons, actually it has violated one of usability goals – efficiency, because it reduced the efficiency to take me directly to the payment page. Clearly, this design is for user experience goals. The company is trying to figure out my needs, since normally people need hotels and cars when traveling abroad. I don’t feel annoyed by these, actually I am quite happy to see these options, because I can compare the rates with booking.com. The same reason holds for Ebay recommends you products you may like, it tries to increase your user experience, say, for example,“Surprising”. If you remove these options, we cannot say that the user experience is degraded, but with these features, users’ experience may be enhanced, without losing anything. They might even surprisingly find something interesting. Last but not least, any recommendations can not be abused. If you overly use recommendations, the users may be annoyed.
The term user experience is becoming more and more popular. Now many companies have job positions called “user experience designer” or “user experience researcher”, because they know what really makes a difference is user experience. My conclusion is that, when designing a product, one should keep in mind both usability and user experience goals. Usability goals are objective criteria and are often task-oriented, which are relatively easier to evaluate. They aim at enabling users to perform tasks in a more efficient and effective way. Good usability ensures users to have a clear mental model of the interface that enables them to confidently predict what will happen in response to their actions. In the best cases, the interface almost disappears, enabling users to concentrate on their work, exploration, or pleasure. This kind of calming environment gives users the feeling that they are “in the flow”, operating at their peak, while attaining their goals (Designing the User Interface, Ben Schneidermann).
User experience goals are more subjective, users sometimes do not know what they want, or what their tasks are. So as an interaction designer, one must understand deeply the users, including the usage context of a product, the behaviour patterns as well as potential needs. UX designers have to think about desirability, about how to frame the offering to increase the usage. If possible, we also need to try our best to influence/persuade users.