Landmarks: A Thought Experiment - Landmarks: GIScience for Intelligent Services - page 27

2.1.1 The Void

Imagine an environment with no structure at all, like in Genesis 1.2: “The earth
was without form, and void; and darkness was upon the face of the deep”. The only
structure given is a flat infinite surface orthogonal to gravity. Walkers are presented
with a monochrome empty plane up to the horizon, under a white sky of diffuse
light. There is no further structure in this environment, and no hint for direction
other than the vertical axis imposed by gravity. There is not even shadow supporting
a sense of direction. All what the walkers experience in this environment is their
own locomotion, and thus path integration. Their body will tell them from which
location they originated. Therefore they can always point in the direction of this
location and guess the covered distance, a mental ability called homing [ 14 ] . In
their desire to establish and maintain orientation in this empty environment the
only location to relate to is this point of origin. Let us call it home . Home is the
only place there is. Thus home becomes a reference point for the exploration of the
environment: A landmark.
If this environment would have force fields that differ by location then sensing
the force differentials could support the sense of direction. For example, if walkers
would be equipped with a magnetic sense, or a compass as an external device,
their mental effort to maintain their sense of direction would be supported con-
siderably [ 21 ] . Similarly if the plane would be tilted towards gravity their sense of
gravity would add observations to path integration.

2.1.2 Adding a Landmark

Now imagine that a walker, after roaming around to discover the environment,
stumbles upon a coin on the ground. This walker, picking up the coin, might feel
lucky. At last she has an experience in an otherwise uneventful environment. This
experience is linked to a location. She will remember the event, and for a while also
its location: Another landmark.
When she returns home she wants to report to her friends where she has found the
coin. How can she do this given that there are no external cues in the environment?
All she can refer to are directions and distances related to her body. She might say:
“Over there [pointing], perhaps 20 steps from here”, the direction physically linking
to her body, and the distance in a quantity relating to an internalized measure that
can be realized by walking. The reproducibility of measures proportional to the body
or body mechanics will help her even in communicating with friends, assuming
they have a body like her. Scheider et al. also concerned about grounding human
experiences of space, wrote ([ 18 ] , p. 76):
Humans perceive length and direction of steps, because (in a literal sense) they are able to
repeat steps of equal length and of equal direction. And thereby, we assume, they are able
to observe and measure lengths of arbitrary things in this environment.