Christa Sütterlin

Illusions of filled lateral and angular extent

SummaryThe common principle of the illusions found by Helmholtz and Botti is the overestimation of a filled extent. They differ in that Helmholtzs illusions of filled angular extent can be accounted for in terms of spatial two-line interactions, whereas Bottis illusions of filled lateral extent cannot. The former observation is consistent with the assumption of interacting orientation-detectors in the visual cortex. The Botti illusion probably depends on global computation in the visual system.

Universals in Apotropaic Symbolism: A Behavioral and Comparative Approach to Some Medieval Sculptures

Artistic works usually are considered in light of the integrated aspects of their parts and within their cultural context. Figures of apotropaic function and value seem to contradict this holistic paradigm, since single traits are found to reappear under different cultural and historical conditions with exceptional conformity and ‘archaic’ perseverance. Comparative and cross-cultural studies have yielded some evidence for the interpretation of similar expressions—such as ‘making faces’, showing the tongue, presenting the buttocks or genitals, etc.—as ritualized forms of a common pattern in human communication.