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5.6 Virtual characters: agents 157

BEGIN SESSION), the former was rated by college students as less honest and it
made them feel less responsible for their actions (Quintanar et al., 1982).

Casting your vote: On the basis of this debate and any other articles on the topic
(see Section 5.6 and the recommended readings at the end of this chapter) together
with your experiences with anthropomorphic interfaces, make up your mind
whether you are for or against the motion.
~
5.6 Virtual characters: agents

As mentioned in the debate above, a whole new genre of cartoon and life-like char-
acters has begun appearing on our computer screens-as agents to help us search I
the web, as e-commerce assistants that give us information about products, as char-
acters in video games, as learning companions or instructors in educational pro-
grams, and many more. The best known are videogame stars like Lara Croft and
Super Mario. Other kinds include virtual pop stars (See Figure 5.9 on Color Plate
6), virtual talk-show hosts, virtual bartenders, virtual shop assistants, and virtual
newscasters. Interactive pets (e.g., Aibo) and other artificial anthropomorphized
characters (e.g., Pokemon, Creatures) that are intended to be cared for and played
with by their owners have also proved highly popular.

5.6.1 Kinds of agents
Below we categorize the different kinds of agents in terms of the degree to which
they anthropomorphize and the kind of human or animal qualities they emulate.
These are (1) synthetic characters, (2) animated agents, (3) emotional agents, and
(4) embodied conversational interface agents.

1. Synthetic characters

These are commonly designed as 3D characters in video games or other forms of
entertainment, and can appear as a first-person avatar or a third-person agent.
Much effort goes into designing them to be lifelike, exhibiting realistic human
movements, like walking and running, and having distinct personalities and traits.
The design of the characters' appearance, their facial expressions, and how their
lips move when talking are also considered important interface design concerns.
Bruce Blumberg and his group at MIT are developing autonomous animated
creatures that live in virtual 3D environments. The creatures are autonomous in
that they decide what to do, based on what they can sense of the 3D world, and
how they feel, based on their internal states. One of the earliest creatures to be de-
veloped was Silas T. Dog (Blumberg, 1996). The 3D dog looks like a cartoon crea-
ture (colored bright yellow) but is designed to behave like a real dog (see Figure
5.10). For example, he can walk, run, sit, wag his tail, bark, cock his leg, chase
sticks, and rub his head on people when he is happy. He navigates through his
world by using his "nose" and synthetic vision. He also has been programmed with
various internal goals and needs that he tries to satisfy, including wanting to play