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5.3 Expressive interfaces 143

5.3 Expressive interfaces
A well-known approach to designing affective interfaces is to use expressive icons
and other graphical elements to convey emotional states. These are typically used
to indicate the current state of a computer. For example, a hallmark of the Apple
computer is the icon of a smiling Mac that appears on the screen when the machine
is first started (see Figure 5.2(a)). The smiling icon conveys a sense of friendliness,
inviting the user to feel at ease and even smile back. The appearance of the icon on
the screen can also be very reassuring to users, indicating that their computer is
working fine. This is especially useful when they have just rebooted the computer
after it has crashed and where previous attempts to reboot have failed (usually in-
dicated by a sad icon face-see Figure 5.2(b)). Other ways of conveying the status
of a system are through the use of:

dynamic icons, e.g., a recycle bin expanding when a file is placed into it
animations, e.g., a bee flying across the screen indicating that the computer is
doing something, like checking files
spoken messages, using various kinds of voices, telling the user what needs
to be done
various sounds indicating actions and events (e.g. window closing, files being
dragged, new email arriving)
One of the benefits of these kinds of expressive embellishments is that they provide
reassuring feedback to the user that can be both informative and fun.
The style of an interface, in terms of the shapes, fonts, colors, and graphical el-
ements that are used and the way they are combined, influences how pleasurable it
is to interact with. The more effective the use of imagery at the interface, the more
engaging and enjoyable it can be (Mullet and Sano, 1995). Conversely, if little
thought is given to the appearance of an interface, it can turn out looking like a
dog's dinner. Until recently, HCI has focused primarily on getting the usability
right, with little attention being paid to how to design aesthetically pleasing inter-
faces. Interestingly, recent research suggests that the aesthetics of an interface can

Figure 5.2 (a) Smiling and (b) sad Apple Macs.