Cognitive Aspects: How People Perceive, Memorize, Think and Talk About Landmarks - Landmarks: GIScience for Intelligent Services - page 81

one is more informative (even a categorical “Turn right at the Catholic church”
would have been), but the additional amount of information is irrelevant in this
context, and hence, neglected by many speakers. The additional information is only
relevant—and then not neglected by speakers—in contexts where the a reference to
the base category would be ambiguous; say, where St. Francis would be not the first
church encountered and finer distinctions have to be made.
In the following two subsections we will focus more narrowly on sketches and
spoken or written verbal instructions. We will leave aside other forms of external-
izations, although they also could provide insights to mental spatial representations
in general, and landmarks in particular. Maps, for example, are rarely the output of
a single person's mental spatial representation, but rich in documenting collective
human landmark experience in an environment. Purely symbolic representations
such as arrows are externalizing aspects of mental spatial representations and
studied in this regard (e.g., [ 102 ] ), however, they are poor about landmarks.
Pointing, as we have mentioned before in the context of path integration, provides
an important insight into mental spatial representations, however, it stays also poor
with respect to landmark knowledge. We also leave aside more literary descriptions,
for example those that try to capture the atmosphere or essence of an environment.
The following two subsections aim in particular to extract these kinds of
knowledge about mental spatial representations:

￿ Elements of mental spatial representations.

We are asking what the atoms of mental spatial representations are. Lynch,
for example, identified elements of graphical representations of cities [ 128 ] . But
Lynch's work was limited to one particular context, or level of spatial granularity.
More work is needed in various contexts, and should include research on qualities
of landmarks, or on landmarkness , since we learned above already that all of
Lynch's elements have landmarkness.

￿ Structures of mental spatial representations.

We are asking how these atoms are connected. Here the hierarchies by
granularity (containment) and by salience (use of anchor points) play a role. But
also research in identifying fundamental qualitative spatial relationships belongs
here. Mark and Egenhofer, for example, have studied the cognitive meaning of
spatial predicates in spoken languages by presenting participants labelled sketch
maps and asking for agreement to the label [ 135 ] .

￿ Individual landmarks.

We are asking which objects in a specific environment have formed the
experience and ensuing mental spatial representation of an individual. Lynch's
sketches do not only reveal elements (categories of types), they also reveal
concrete instances of these elements. In a similar vein, collecting landmarks
from corpora of place descriptions [ 39 ] or from information retrieval approaches
(e.g., [ 24 , 176 ] ) should allow a mapping of individual, collective, and context-
aware mental spatial representations of particular environments, despite our
awareness that completeness can never be reached.