The Background - Artificial Human Sensors: Science and Applications - page 8

of Singapore teenagers. Possible reasons for this were related to current reading
and writing habits, and reading at close distances in the educational system.
1.2.3 The Smell and Taste Ability
Chemical compounds in nature are features of importance and a survival source
of information for animals. Tasting and smelling have been since ancient time
essential influence in nutrition and food selection. The taste related gustatory and
smell related olfaction systems are fundamental senses in the mating process for
creating and maintaining territories. The olfaction and gustatory systems are in
both cases referred to as chemical senses due to the fact that the adequate stimulus
consists of molecules that bind to the receptors of the sensory cells. Animals use a
process called chemo-reception when responding to chemicals in the environment.
The human chemical sensing system consists basically of two primary tech-
niques to detect chemical presence.
Firstly, by contact inside the mouth, which primarily relates to the four
taste qualities which are sweet, sour, salty and bitter. Umami is also related
to this group. The process provides a structural risk that possibly unhealthy
compounds accidentally enter the body. The sensing system in this case is not
effectively detected by the other perceptual organs, i.e., the object enters the
mouth before a possible complementary chemical, visual, tactile or auditory
evaluation has been made.
Secondly, by distance in close proximity of the body, provides an effective
selection of airborne chemicals for food and avoidance of potentially toxic com-
pounds. This process is considered to be of benefit for survival purposes when
making it possible for an evaluation that continuously can be performed out-
side the body and hopefully on a safe distance before the individual gets in
contact with the chemical stimuli.
The perceptions of smell and taste are often combined, as interacting with food
stimuli when swallowed or inhaled. The typical flavour is based on the individual
conception concerning the object stimuli and experience. However, in spite of the
fact that we all have individual preferences, there is a general understanding that
the gustatory and olfactory systems are necessary to ensure a good quality of life.
According to Spielman (1998), more than two million Americans suffer from dis-
orders that affect the sense of olfaction and/or gustatory.
Regardless of the variety of the level of flavour preferences in a population,
related to age, gender and social patterns, one important issue still arises, the ques-
tion about what is considered to be “normal smell and taste performance” in a
population.
According to Bear (1996), most of the chemical based flavour is collected by
the olfaction system. Up to 75-80 % of everything we perceive, when having a nice
meal is considered to originate from the smell and only a minor part can related to
be received from the gustatory system. This may be of importance when consid-
ering that the elderly normally decline in their performance of smell capabilities