Abstract
Op artists, such as Bridget Riley, frequently use monochromatic abstract compositions to create works which produce a strong percept of illusory motion in the observer. Previous work has looked at the effects of eye-movements (Zanker, Hermens & Walker, 2008, Perception, 37, ECVP Abstract Supplement: 150) and the image statistics (Zanker, Hermens & Walker, 2008, Perception, 37, ECVP Abstract Supplement: 70) in an attempt to explain and optimise such illusory motion. Preferential looking literature suggests that the eye-movements needed to see this percept are also subject to top-down influences which result in increased fixation time on preferred images. Here, we use a combination of cumulative fixation time and fixation sequence which has been shown to correlate with aesthetic preference (Holmes & Zanker, 2009, Journal of Vision [abstract], 9(8): 26.) to provide the selection pressure for an evolutionary algorithm operating on a chromosome encoding the parameters of stimuli known to produce this percept. By varying the presentation time of the stimuli and tracking the eye-movements of 20 participants in a free-looking paradigm, we show that with increased time to view, participants attention is attracted to those stimuli with a stronger motion percept and that these stimuli are robustly preferred by the participants when retested using a 2AFC experiment 1 week later. The results demonstrate that general aesthetic preferences can be detected using evolutionary algorithms that use oculomotor statistics as fitness information, thus providing a reliable and robust paradigm for use in future studies of subjective decision making and experimental aesthetics.
Suppported by EPSRC Grant 05002329.