Information Technology Reference
In-Depth Information
4
Input/output devices
Selecting the right input and output devices is a crucial point to obtain simple
and efficient interaction. Such devices can be modified and/or adapted for
being employed by particular users like the disabled. Moreover new devices
can be designed for this purpose.
4.1
Input devices
Interaction can start when the user is enabled to communicate her intentions
to the machine so that they can be processed. An input device is able to
transform the information provided by the user into data that can be
recognized and understood by the system [11].
When selecting the role of a particular input device, the interaction
designer has to keep in mind that it will help users to carry on their work in a
secure, efficient and pleasant way.
In general, input devices should exhibit the following features:
a)
They are designed for adapting to the user's physiological and
psychological features; this is a very useful feature to obtain devices to
be used by disabled or unskilled people.
b)
They are suitable for the tasks involved in the interaction; as an example,
to draw lines or sketches a tool like the electronic pen is needed that
allows continuous movement over a surface.
c)
They are suitable tools in the environmental context of the interaction; as
an example, a vocal interface could be useful to avoid the keyboard but
only when the environment is not noisy [11].
4.1.1
Keyboards
A keyboard is a set of two-state buttons that can be pressed (on state) or not
(off state: default). The user can press down single keys or a combination of
them. Keyboard is a discrete device because it does not allow continuous
interaction [11].
4.1.2
Pointing devices
Pointing devices are used when a point or a line have to be pointed out or
selected in the 2D/3D space. Some of them are joystick, trackball, mouse,
electronic pen and so on. Pointing devices allow continuous interaction even
if mouse and joystick allow discrete interaction through their buttons.
Joysticks act along two directions, and they are sued often when the task
involves specifying a direction or speed value. Joysticks can be used in plants
when a ubiquitous system is used to move an equipment remotely [11].
