3.2 Familiarity
Rebo has a life-like appearance in Fig. 1 and facial expressions to acquire familiarity with a user. We
adopt the concept of "intermediate entity between artifacts and animate beings". Rebo is not only a tool but
also a pet to users. The body of Rebo is covered with soft and bouncy cloth and it is comfortable for users
to touch Rebo. When the user strokes Rebo, it changes its facial expressions to inform him or her of various
emotional states of Rebo. We consider this makes the user more comfortable with Rebo. Rebo currently has
four different facial expressions like "Sleep", "Normal", "Select TV channels" and "Change sound
volume". Therefore, interaction with Rebo can be the purpose of the user as well as manipulation of home
electric appliances. We believe that this concept plays an important role for establishing familiarity
between users and Rebo.
intensity as the user carries out given actions. As for intensity of feedback behavior, it is assumed that the
volume, frequency and quality of representation are changed. Some patterns of feedback behavior that can
be used are changing lights displayed, sounds emitted, or timing of movements. Fig. 3(a) shows the
conventional method for exhibiting feedback behavior. When a function of a machine is executed, feedback
is provided for the user. However, the machine provides no feedback at all if the user does not perform a
function.
In contrast, with action sloping shown in Fig. 3(b), a machine exhibits feedback behavior even when a
function is not performed. It provides feedback in response to user's incomplete manipulation. Therefore,
action sloping enables users to understand relationship between user's action and the machine's functions.
For example, we can consider a case of using a TV remote as follows. When a power button is pushed
(triggering action is performed), the TV tum off (feedback behavior). A user receives feedback of hislher
manipulation when the TV actually turns off. In contrast, action sloping gradually provides feedback before
the TV actually turns off. Before the user touches the button, the TV decreases the image dimensions to
express "the TV is likely to tum off'. This action sloping requires a sensor that can measure the distance
between the user's fmgers and the button. In this study, a user interacts with Rebo by stroking it. This kind
of interaction manner bears a continuous action and easily achieves action sloping.
We utilize this feature and propose partial execution as a way for the user to notice functions of the
machines. Partial execution is a feedback expression method that provides a meaning of users'
manipulation by showing a part of an executing function. For example, when a user strokes Rebo for a
short time to tum off the TV, Rebo decrease the image dimensions of the TV for a short time. If the user
strokes Rebo for a long time, it decreases the image dimensions and turns off the TV power eventually.
Feedback expressions of the machine strongly depend on its functions and are designed for each
application. We need to develop the methodology to design adequate realization of action sloping in
various domains related to a remote control.