Mental representations of spatial relations

Three classes of theories of the mental representation of spatial relations were tested. Nonhierarchical theories propose that spatial relations among objects in an environment are mentally represented in networks or in imagelike, analog formats. The distinctive claim of these theories is that there is no hierarchical structure to the mental representation. Hierarchical theories, on the other hand, propose that different “regions” of an environment are stored in different branches of a graph-theoretic tree. These theories can be divided into two classes of subtheories depending on the kinds of relations encoded in memory: Strongly hierarchical theories maximize storage efficiency by encoding only those spatial relations needed to represent a layout accurately; partially hierarchical theories predict redundancy in the representation, such that many spatial relations that can be computed also will be stored explicitly. These three classes of theories were tested by having subjects learn the locations of actual objects in spatial layouts or the locations of objects on maps of those layouts. Layouts and maps were divided into regions with transparent boundaries (for the layouts, string on the floor; for the maps, lines). After learning the layouts or maps, subjects participated in three tasks: item recognition, in which the variable of interest was spatial priming; direction judgments; and euclidean distance estimation. Results from all three tasks were sensitive (a) to whether objects were in the same region or in different regions and (b) to the euclidean distances between pairs of objects. These findings were interpreted as supporting partially hierarchical theories of spatial representations. Computer simulations supported this conclusion.