The Perception - Artificial Human Sensors: Science and Applications - page 66

very small fraction, about 1%, that a person is aware of, Norretranders (1998). The
human perception also seems to exhibit a huge information filter that with preset
preferences, or earlier experiences and knowledge, and provides a person with a
refined focus of situational awareness.
Just as one object or situation can give rise to multiple perceptive responses,
an object may also fail to give rise to any perceptual responses at all. That is, if
the sensation has no grounding in a person's earlier experience, or of any other
interest, then the person may literally not perceive it. This process is called the

passive perception, Goldstein (2006).
The crucial term in our daily life is attention that according to Endsley, (2000),
is an essential process of situational awareness. Despite many definitions, the
notions to express knowledge that there are different ways of processing sensory
organs input in the brain, accentuating some aspects of the surrounding scene and
ignoring others. As the visual organ may provide as much as 80-85% of the sen-
sory inputs, we usually use phrases when saying “to see is to attend”, Yantis (2003).
For instance, due to the crucial involvement of attention in visual awareness, and
“change blindness” effects of “inattentional blindness” can prevent objects from
being seen despite being directly fixated on, Rensink 2004), Velichkovsky (2002).
There are two basic theories of perception: passive and active perception.
The passive perception process can be compared to a person who is observing
the environment without taking any action. The person, is collecting information
mainly by the vision senses and passively observing the scene. In this mode, the
person does not take any specific action in mind or other expectations connected
to the input sensations. The individual is simply acting as an observer, passively
observing the envionment, Biel (2002). The opposite process is of course the ac-
tive perception process, where the individual is actively taking part in the situ-
ations in the environment and provides decision and actions thereof. The active
person is taking part in the happenings in the environment and providing a situ-
ational awareness that is probably making the person an important player in his
surroundings as illustrated in Fig. 3.7.
By adding the active perception principle to an artificial system, the “intelli-
gence” in the system provides a possibility to reformulate a mission and change
the behaviour, or system parameters, according to dynamic situations in the
environment. This property facilitates the possibility to redirect the sensation pro-
cess to the area of interest, Freeman (1999). The active perception paradigm was
orginaly intended to be applied in the vision systems when introduced by Bajcsy,
(1985).

3.2.2.3 BODY LANGUAGE

It is widely accepted that body language is a powerful psychological source of
information reflecting emotions and intentions in our daily life when interacting
with people. An individual's body language may influence us within a part of
a second, but during that time we have already formed an opinion about the