Information Technology Reference
In-Depth Information
The mechanisms for the two senses are separate, but functionally they are much
more difficult to separate, and they usually operate in tandem. For this reason, the
two senses are associated with three types of tactual perception:
• Tactile perception, which is solely mediated by changes in cutaneous stimula-
tion. Tactile perception always occurs within the context of a particular static
posture, and may depend on that posture.
• Kinesthetic perception, which is (mostly) mediated by variations in kinesthetic
stimulation. This includes situations where the cutaneous sense only indicates
contact with the stimulus, and does not provide any spatial or textural infor-
mation about the stimulus.
• Haptic perception, which is the most common type of tactual perception. It
involves using information from the cutaneous sense and kinesthesis to under-
stand and interpret objects and events in the environment.
In the rest of this section, when we refer to touch, we will be referring to haptic
perception, unless otherwise specified. Most devices that are used to provide input to
computer-based systems make use of haptic perception. In general, however, most
haptic devices only support interaction using the hands or fingers, even though users
could (theoretically, at least) use any part of their body. There is, however, a
growing number of devices that support input using the feet, such as the highly
sophisticated da Vinci surgical system
1
which has been successfully used in cancer
surgery. The feet are also used to move around in virtual reality systems. The mouth
and other parts of the body tend to be supported somewhat less, but they can be
critical in interfaces for people with disabilities who cannot use their limbs, and
increasingly for the military in unusual situations or circumstances.
In this section we will focus our discussions on how people use hands and
fingers to interact with systems. These discussions will consider the most common
types of haptic devices that support interaction with computer-based systems. The
future may include other devices, such as pens (e.g., Tian et al.
2008
), multi-touch
interfaces on a wider variety of objects (e.g., Jiang et al.
2012
), or gestures, but
these could be analyzed in a similar way.
3.3.1 Physical Keyboards
Physical keyboards—we use the term here to distinguish them from the soft
keyboards that are used on touch screen devices—have a haptic interface. The feel
of the key clicks provides you with haptic feedback about whether a keypress has
been detected (and hence whether the corresponding character will appear on the
associated display screen). Sometimes people will complain about the feel of a
particular keyboard. Usually they are referring to the position and shape of the
1
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