Cognitive Aspects: How People Perceive, Memorize, Think and Talk About Landmarks - Landmarks: GIScience for Intelligent Services - page 74

Stevens and Coupe point also to the efficiency gains of hierarchical reasoning. If a
relationship can be stored at a coarser level of granularity then all the relationships
between pairs of objects contained in both aggregates do not need to be stored. The
adopted strategy in the particular example seems to be:

￿ San Diego is in California, Reno is in Nevada (lifting the problem to a coarser

level of granularity).

￿ Nevada is East of California (reasoning about directions at this coarser level of

granularity).

￿ Ergo, Reno must be East of San Diego (projecting the reasoning result to the finer

level of granularity).

Look at exhaustive search in contrast. An exhaustive search for the direction from
San Diego to Reno would require to activate in working memory the vector space
of cities in the western part of the USA, and then to determine by vector addition
the direction between the two named cities. No doubt that this exhaustive search is
possible for the mind. A person living at the west coast of the USA may have learned
the configuration of cities from travelling around extensively or from studying maps.
But the cognitive load is significant, compared to lifting the problem up to the
coarser level of granularity.
But the experiment also demonstrates the price to pay. A heuristic is a mental
shortcut. It has become part of System 1 because it provides satisfactory solutions
in general, whilst accepting that it does not always guarantee the correct (or optimal)
solution [ 64 , 94 , 220 ] .
Inspired by the above experiment, Hirtle and Jonides [ 83 ] hypothesized that
mental spatial representations of inhomogeneous distributions of objects are also
hierarchic. Clusters exist in the real world. For example, buildings are dense in cities
and scarce in rural areas, cities are dense in populated countries and absent on sea,
and so on. People judge distances between these clusters differently than within
clusters, and thus, they form tree-like mental hierarchical structures formed by
these clusters, even in absence of boundaries or barriers as in Stevens and Coupe's
experiment.
Moreover, McNamara [ 141 ] studied how people learn environments and then
make judgements from memory. He presented his participants either a physical
environment or the same environment represented on a map. Both presentations
had a hierarchic structure. Objects in the physical environment were laid out in
regions marked on the floor, and correspondingly the map space was partitioned
into regions. After a learning phase participants had to engage in three tasks: item
recognition, direction judgements, and Euclidean distance estimation. The results
from all three tasks were sensitive to whether objects were in the same region or in
different regions, which is a clear indication of a hierarchically structured mental
spatial representation of a learned environment.
Thus, there is strong evidence for a hierarchic organization of mental spatial
representations by granularity, more precisely in containment hierarchies.