Accommodating both Experts and Novices in One Interface

Jing Wu
Department of Computer Science
University of Maryland, College Park, MD 20742 USA
jingwu@cs.umd.edu

April 19, 2000

There is ample evidence to support the intuitive notion that experts behave differently from novices. Even though some interfaces are only intended to be used by novices, most interfaces need to be designed to accommodate both novices and expert users at the same time. Accelerators, online help, adaptive interface are example of the possible ways to accommodate both users in one interface. Guidelines are provided for designing user interface to support both experts and novices.

Novice and expert users of an interface system differ greatly. Accommodating both types of users in one interface is a challenge as well as a necessity for most user interfaces.

Users' experience differs in different ways. The following figure shows the "user cube" of the three main dimensions along which users' experience differs: experience with the system, with computers in general, and with the task domain [7].

The users' experience with the specific user interface under consideration is the dimension that is normally referred to when discussing user expertise, and users are normally considered to be either novices or experts, or somewhere in-between.

This paper analyzes different approaches to support novice and expert users and provides some guidelines for accommodating both kinds of users in one interface.

Usability has multiple components of which learnability, and efficiency are two most fundamental usability attributes. Usability research has focused on different component in different time of the history [8].

Back in 1970s, software was designed for super-geeks and nobody else. When the field of human-computer interaction was established in 1983, learnability was the research focus. Classic papers like Jack Carroll's LisaLearning demonstrated that even the best commercially available personal computer was much harder to learn than claimed by Apple. By the late 1980s we had a handle on how to design for the novice user.

Much research in the late 1980s and early 1990s concerned experienced user performance. In 1991, Jordan[5] provided the idea that there are three distinct components that influence the usability of an interface--Guessability, Learnability, Experienced User Performance.

Now it is time to combine the previous efforts and design the interface to be both easily learnable and highly efficient. It is time to accommodate both novice and expert users in one interface.

There is ample evidence to support the intuitive notion that experts behave differently from novices [10]. Experts do not just know more, they know differently. Experts do more chunking than novices. This means that they are able to take large amounts of information and see it as connected units. They have a rich set of structures within which to characterize new problems and a sophisticated set of high level concepts about the domain.

When using an interface, expert users can quickly form goals and sequences of actions to achieve the goal. They would like the number of interactions to be reduced and thus the action execution is accelerated. They require that the pace of interaction is quick. In a word, they want a highly efficient interface.

The novice users require the interface to be easy to learn. Ideally, They would like the interface to be guessable which means that users who do not have previous experience of the system can use the interface. Besides this, novice users would like to gain the skills and knowledge about the interface and become expert users quickly.

Even though some interfaces are only intended to be used by novices, in that almost nobody will use them more than a few times, most interfaces need to be designed to accommodate both novices and expert users at the same time. The reasons are:

• Novice users gain skills by using the interface and eventually become expert users.
• Almost all systems have so many features and so many uses that any given user only makes extensive use of a small subset. Even an "expert" user may be quite novice with respect to many parts of the system not normally used by that user.

The following figure shows the idealized performance curve, a possible performance curve for a system which focuses on the novice user and a possible performance curve for a system which focuses on the expert user[5,7].

Ease of learning refers to the novice user's experience on the initial part of the performance curve. Highly learnable systems have a steep incline for the first part of the learning curve and allow users to reach a reasonable level of usage proficiency within a short time. Practically many user interfaces have performance curves that start out with the user being able to do something(have non zero efficiency) at time zero. The examples are the so-called walk-up-and-use systems, like a kiosk for making dinner reservations in an amusement park. There are also many systems that have zero efficiency at time zero. A system's efficiency refers to the expert user's steady-state level of performance at the time when the performance curve flattens out.

Our goal is to design the interface so that the performance curve rides the best parts of the blue curve and green curve and reach the idealized curve. To achieve the goal, we need to combine the efforts to support the novice users with the effort to support expert users in one interface.

One basic strategy is to create a level-structured approach [11]. Novices can be taught a minimal subset of objects and actions with which to get started. They are most likely to make correct choices when they have only a few options and are protected from making mistakes when they are given a training-wheels interface. Learner-Centered Design, which suggests the need to design scaffolding-fadeable supports was proposed in 1994[12]. LCD guides the design of software in order to support the unique needs of learners: growth, diversity, and motivation. Guided Learner-Adaptable scaffolding in which the learner controls the fading of scaffolding with guidance and support provided by the system [13,3]. After gaining confidence from hands-on experience, these users can progress to ever-greater levels of task concepts and the accompanying interface concepts. The learning plan should be governed by the user progress through the task concepts, with new interface concepts being introduced only when they are needed to support a more complex task. For users with strong knowledge of the task and interface concepts, rapid progress is possible.

Another common way to achieve this "best-of-both-worlds" effect is to include accelerators in the user interface[7]. Accelerators are user interface elements that allow the user to perform frequent tasks quickly, even though the same tasks can also be preformed in a more general, and possibly slower, way. Typical accelerators include abbreviations, having function keys or command keys that package an entire command in a single keypress, double-clicking on an object to perform the most common operation on it, and having buttons available to access important functions directly from within those parts of the dialogue where they may be most frequently needed. Pen computers, virtual realities, and some mouse interfaces may also use gestures as accelerators.

A good example of a shortcut to make a frequent operation faster is the use of a structure generator in a hypertext authoring system[4]. Since hypertext authors may often want to generate large numbers of similar hypertext structures with a given pattern of typed nodes and links, they can work faster if the system allows them to define templates of these structures and to generate sets of nodes and links based on a template in a single operation. Macro and scripting facilities can be used to achieve similar effects in traditional command languages, and similar facilities are also being introduced to graphical user interfaces.

Click-ahead is a technology in the Graphical User Interface that is similar to the Type-ahead in command line interface. Users can click on the spot where the "OK" button will appear to dismiss dialog boxes before they have even appeared, and they can click in partly obscured windows before they have been made active.

Users should be allowed to jump directly to the desired location in large information spaces, such as a file or menu hierarchy[7]. A hypertext-like approach can be used with links between information elements that are likely to be used with links between information elements that are likely to be used together. Users may be allowed to give their own names to some locations they find especially important. By doing so, users can build up a list of bookmarks that will enable them to return quickly t a small set of locations[1].

Users should be able to reuse their interaction history[2]. A study of a command-line system showed that 35% of all commands were identical to one of the five previous commands and that 74% of the commands had been issued at least once before. Thus, a simple menu of the last few things the user had done would make it possible for the user to reissue a large number of commands without having to reenter them. Even though command reuse is simpler for command-language interfaces, some direct manipulation interfaces allow users to reissue the last formatting command or repeat the last search command by a simple command-key shortcut. It is also possible to use a kind of comic strip to show previous states of a graphical interface as miniatures using a principle called a visual cache to allow fast direct access to those states[6].

Designing good online help is a typical way to assist the novice users without getting in the way of the experts. Please refer to Empirical studies of online help about designing online help.

Enabling users to customize the user interface is another powerful way to accommodate both users. For example, an interface can permit users to control the density of informative feedback that the system provides. In this way, novices can have more information to confirm their actions, whereas frequent users can reduce the distracting feedback. An interface can also allow users define more hot-keys to save typing time and complete the complicated tasks. There has already been much research effort in the adaptive systems, which automatically adjust the interface or content provided by the system[9]. Such system can accommodate users' differences as well as changes. For more information, please refer to Application of Users Modeling for Adaptive and Adaptable Software Systems.

An interface can accommodate both experts and novices by providing both easily accessible and recognizable basics for the novices and providing shortcuts and ways to access more complex features and settings to the expert. Here are some guidelines for supporting both experts and novices in one interface:

• Identify your intended user group. If you are designing a walk-up-and-use system, or an interface that requires a little reading of the instructions, such as installation programs, disk formatting routines, and tax return programs that change every year, concentrating on supporting novice users is the right choice for you. For most other interfaces which needs to accommodate both types of users, the following guidelines may be useful for you.
• Design the top level of your interface to be simplified as much as possible. Include only the basic, simple features in your top level of menu, initial appearance of the dialogue,etc. Hide the more advanced features that are harder to use through layers of menus or "advanced" section of properties menu or dialog.
• Provide accelerators for expert users. Provide command abbreviations, function keys(hot keys), provide click-ahead when possible. For the hidden advanced features, provide function keys or any other techniques to allow expert user to jump directly to the advanced features.
• Show the corresponding short cut of a normal menu item with the menu item so that novice users can get to know the short cut by using the interface frequently without bothering them when they first use the interface.
• Provide online help to assist novice users without getting in the way of the experts. Interfaces that are solely intended for novices may not special help systems, as they should include all the necessary user assistance in the primary interface itself. About designing online help, please refer to Empirical studies of online help .
• Provide properties menus that allow expert users to change default settings to more suits their needs. Allow expert users to define their own short cuts. Design your interface to be adaptive so that expert users can have more freedom to control the interface.
• When a win-win solution can not be found to satisfy both requirements, follow what your usability goals require.

Learnability and Experienced User Performance are two fundamental factors in the usability of an interface. Good interface should be able to accommodate both expert users and novice users in one interface.