The classification and analysis of spirals in decorative designs

Structure in decorative patterning has been used to identify perceptual preferences
and broader social and cultural patterning of a society. This thesis proposes a new
method of analysis and classification of decorative spirals as a test of whether the
analysis of an individual type of geometric decorative motif in isolation can reflect
social and cultural trends in a similar manner. The proposed analysis method, which
takes a quantitative, bottom-up approach to classification, was compared with a topdown
classification method used in previous studies based on mathematical spiral
forms. Similarities were found across the two classification methods, both are clearly
strongly influenced by the expansion rate of the spiral but the newly proposed method
is felt to offer a more flexible approach to the classification of motifs which
accommodates gradual variation and the decorative properties of the motifs beyond a
simple mathematical curve.
The proposed method was tested on four archaeological case studies: Egyptian scarabs
of the Middle Kingdom and First and Second Intermediate Periods, Cypriot Bronze Age
painted pottery and gold-work, Shang and Western Zhou Dynasty bronze vessels, and
Japanese Jōmon Period pottery. Quantification and cluster analysis of spirals in these
studies identified variation in motif shape that could be attributed to the production
method but the chief finding was one of homogeneity across the four cultures and a
limited range of forms of decorative expression which suggests an influence of natural
spiral forms on decorative examples across the cultures sampled. An analysis of the
possible influence of spiral optical effects arising from disturbances in the functioning
of the visual cortex on decorative spirals did not yield significant results.