Looking at Islamic Patterns II: Making Sense of Geometry
Islamic geometric patterns are arrangements of interlocking stars and polygons. Why do they attract our attention? Following Silvia's model, interesting stimuli are hard to process yet comprehensible. To understand what it means to make sense of a geometric pattern we explore representations of space and geometric structure. Perceptual and linguistic evidence yields small sets of primitive objects and qualitative relations that suffice to build a synthetic geometry of perceptual space; constructing patterns requires the capability to divide lines and circles into equal parts, but does not rely on measuring lengths or angles explicitly.We compare eight representations of a star motif that demonstrate different approaches, different spatial frames of reference, and different levels of abstraction. A representation may be parametrised to represent a category, which allows us to verify that it captures salient features (the object should not be an anomaly in the category). We conclude that sequential constructive representations (algorithms) do not provide a good model for spatial structure, and that compression (encoding) and comprehension (making sense) are distinct.Chunking and schemas capture generic structure in unfamiliar contexts, in particular repetitive, composite, modular and hierarchical structure. The large corpus of Islamic patterns exhibits constant innovation over hundreds of years. We give examples to illustrate a clear trend towards increasingly complex structure, of both modular and hierarchical forms.