Cognitive Aspects: How People Perceive, Memorize, Think and Talk About Landmarks - Landmarks: GIScience for Intelligent Services - page 87

￿ There will be longer (richer) and shorter (leaner) route descriptions facilitating

an instruction follower to reach a target. The maxim of brevity would prefer the
shorter ones. In the longer ones the maxim of relevance will identify irrelevant
or redundant references.

￿ There will be route descriptions that will fail to guide a particular instruction

follower to a target. These descriptions violate the maxim of relevance by
omitting relevant information.

Thus, a different instruction follower may require a different message. However, one
important conclusion follows from these rather abstract considerations. Of all prag-
matically equivalent descriptions guiding to the target the shorter descriptions may
be the better route descriptions. A tangible reason for this assumption is the limited
capacity of short term memory [ 32 , 110 , 144 ] . Thus, in accord with other forms of
externalizations, route descriptions reveal more about the structure of mental spatial
representations in connection with strategies of spatial and communication abilities,
and less about the content of mental spatial representations.
The assumption of preferences for shorter descriptions has actually been
confirmed in independent research offering further insight in the internal structure
and content of good route descriptions (e.g., [ 38 - 40 , 127 ] ). This cognitive and
linguistic research has again to rely on indirect observations since there are no
formal criteria for judging the quality of route descriptions other than whether the
instruction taker has reached the target. Indirect ways of observation are:

￿ A purely descriptive approach of linguistic structure. The result is a character-

ization of a route description rather than an assessment. It permits at least a
qualitative comparison between route descriptions for the same route.

￿ Ratings of human route descriptions by local experts. In principle this method

can be applied in situ, e.g., after route following, or in a survey relying on the
mental spatial representations of the raters.

￿ Navigational performance by instruction followers unfamiliar with the environ-

ment. In principle this method can collect whether followers succeed, but in
addition can also survey how comfortable they felt.

￿ Comparison of human route descriptions with some algebraically produced route

descriptions. Algebraic approaches are suited to produce minimal instructions
according to some model, but since the model can mismatch with a context
there is no guarantee for producing successful descriptions, let alone shortest
successful ones. Hence, generally the algebraically produced route description
have to be tested in a control experiment as well.

One of the first investigations of this kind were Wunderlich and Reinelt's [ 241 ]
linguistic study of forms of speech in route descriptions. They worked from a
corpus of route descriptions to identify four phases in the full discourse: an opening
(“Excuse me, can you tell me ...”), the route instructions itself (the path to
be followed), an optional securing phase (ensuring that the message has been
conveyed), and a closure (“Thank you”). In the route instructions they found patterns
identifying landmarks as intermediate destinations and locations of reorientation.
This structure was close to a formal model proposed before by Kuipers [ 109 ] .