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142 Chapter 5 Understanding how interfaces affect users

The main aims of this chapter are to:
Explain what expressive interfaces are and the affects they can have on
people.
Outline the problems of user frustration and how to reduce them.
Debate the pros and cons of applying anthropomorphism in interaction
design.
Assess the believability of different kinds of agents and virtual characters.
Enable you to critique the persuasive impact of e-commerce agents on
customers.

What are affective aspects?

In general, the term "affective" refers to producing an emotional response. For ex-
ample, when people are happy they smile. Affective behavior can also cause an
emotional response in others. So, for example, when someone smiles it can cause
others to feel good and smile back. Emotional skills, especially the ability to ex-
press and recognize emotions, are central to human communication. Most of us are
highly skilled at detecting when someone is angry, happy, sad, or bored by recog-
nizing their facial expressions, way of speaking, and other body signals. We are also
very good at knowing what emotions to express in given situations. For example,
when someone has just heard they have failed an exam we know it is not a good
time to smile and be happy. Instead we try to empathize.
It has been suggested that computers be designed to recognize and express
emotions in the same way humans do (Picard, 1998). The term coined for this ap-
proach is "affective computing". A long-standing area of research in artificial intel-
ligence and artificial life has been to create intelligent robots and other
computer-based systems that behave like humans and other creatures. One well-
known project is MIT's COG, in which a number of researchers are attempting to
build an artificial two-year-old. One of the offsprings of COG is Kismet (Breazeal,
1999), which has been designed to engage in meaningful social interactions with hu-
mans (see Figure 5.1). Our concern in this chapter takes a different approach: how
can interactive systems be designed (both deliberately and inadvertently) to make
people respond in certain ways?

Figure 5.1 Kismet the robot expressing surprise, anger, and happiness.