Landmarks: A Thought Experiment - Landmarks: GIScience for Intelligent Services - page 28

They then went on to develop a theory of steps between foci of attention. In our
thought experiment we stick with the embodied experience, memory and commu-
nication of the walker (coming back to formal models in Chap. 4 ) . In this regard it
is interesting to see how instead of words the walker used pointing to communicate
the direction. Finding words of similar accuracy in this environment would have
been quite difficult. The distance, however, was expressed in a quantitative manner.
A qualitative description might have come to mind more easily: “Over there
[pointing], not too far from here”. The qualitative description can be generated with
less cognitive effort (we will come back to 'quality over quantity' in Sect. 3.3.2.1 ) ,
but its realization might be more uncertain. In addition, the interpretation of a
qualitative term is context-dependent; not too far does mean different things when
talking about a car ride or an exploration of the immediate neighborhood, and in this
empty environment there is not much shared experience between the walker and her
friends that would establish context.
For her friends, the realization of her place descriptions is subject to uncertainty.
While an instruction “20 steps” may produce less uncertainty than “not too far”,
it also takes more cognitive effort to realize by requiring counting. And since the
coin was picked up by the walker, the landmark experience of her friends is only a
mediated one.
Human bodies vary. For example, using foot lengths or step lengths as
measures depends on an individual's body and can be reproduced by another
person only with some uncertainty. Hence, when quantities need to be accu-
rate some agreement is required on an absolute measure, which is a measure
independent from an individual body. Most standardized unit measures are
anthropomorphic, based either on average body dimensions (e.g., the length
of a foot), or on human body movement (e.g., the length of a step). Even
the meter , our today's standard unit according to the International System of
Units ( SI , from Système International d'Unités), was defined as a breakdown
of the length of a great circle of the Earth to a unit in some relation to the scale
of the human body. In order to be reproducible by everybody, an absolute
distance measure requires from an individual learning their individual body
properties (e.g., step length) compared to the standard. With other words,
absolute measures require an additional layer of cognitive effort in realization.
Now, whether quantitative or qualitative, the tuple of distance and direction is
well-known in geometry as polar coordinates. Coordinates are only meaningful
within a given reference system, and in the given scenario the coordinates can
only be embedded either in the egocentric reference system of the body of the
speaker or of the recipient [ 11 ] . It is up to the speaker to convey the intended
interpretation. For example, the speaker could have said: “Straight, not too far”.