Cognitive Aspects: How People Perceive, Memorize, Think and Talk About Landmarks - Landmarks: GIScience for Intelligent Services - page 53

Grabbiness is related to affordance [ 63 ] . If objects or events have to grab
attention to become landmarks they must stand out in their neighborhood, or afford
support in orientation, wayfinding and other spatial tasks. Since people continuously
and mostly subconsciously maintain their orientation in an environment (another
System 1 function), some external, perceivable properties must exude affordance
to be used in short-term orientation. Other perceivable properties must exude
affordance as long-term spatial anchor points. Again other perceivable properties
must exude affordance supporting route planning, for example street signs or
departure boards in the environment of a wayfinder. Affordance is task-bound or
consciously purposeful. A wayfinder will study the departure board, but the cleaner
will ignore it. And since the departure board grabs attention from travelers, and is at
a central place for travelers, it may become a spatial anchor point, a landmark in their
mental spatial representation helping with local orientation or route descriptions.
For example, for tourists arranging to meet at 5 p.m. under the departure board of
the city's train station makes perfect sense.

In his groundbreaking work on conflict Schelling brought up an example of
non-verbal communication that relates to affordance:
You are to meet somebody in New York City. You have not been instructed where
to meet; you have no prior understanding with the person where to meet; and you
cannot communicate with each other. You are simply told that you will have to guess
where to meet and that he is being told that you will have to guess where to meet
and that he is being told the same thing and that you will just have to try to make
your guesses coincide. This problem showed an absolute majority managing to get
together at the Grand Central Station (information booth), and virtually all of them
succeeded in meeting at 12 noon ( [ 188 ] , p. 56).

3.2.2 Properties That Grab Attention

But what is it about some objects and events that grab this attention? While in
principle the world is a continuous phenomenon, the human mind classifies visual
and other perceptions of its environment and identifies discrete objects in this
continuous environment. Visual perception alone has already self-organizing and
holistic processing built in. This was discovered and described by Gestalt theory
long before a neuroscientific understanding could be developed ([ 48 , 200 , 236 , 237 ] ,
but also [ 138 ] ). Ehrenfels characterized the fundamental problem of Gestalt psy-
chology with these words:
Here we confront an important problem [:::] of what precisely the given presentational
formations (spatial shapes and melodies) in themselves are. Is a melody (i) a mere sum of
elements, or (ii) something novel in relation to this sum, something that certainly goes hand
in hand with, but is distinguishable from, the sum of elements? ( [ 48 ] , p. 250, translation
from German following [ 200 ] ).