Zandvakili A, Aghdaee S M, 2004, "Differential effects of test stimulus configuration on magnitude of MAE generated by first-order and second-order motion" Perception 33 ECVP Abstract Supplement
Differential effects of test stimulus configuration on magnitude of MAE generated by first-order and second-order motion
A Zandvakili, S M Aghdaee
First-order and second-order rotating logarithmic spirals were presented to subjects (adapting stimuli) and the magnitude of MAE was measured. The test stimulus was either the same as the adapting spiral (SS) or its mirror image (MS). Since in the MS condition all contours of the adapting and test stimuli are 90° apart, local motion detectors tuned to the directions of the mirror-image spiral fail to respond and therefore do not contribute to the observed MAE. The difference between the MAE strength generated by the SS and MS was then calculated and normalised. The normalised difference of magnitude of MAEs generated by first-order motion was significantly larger than that generated by second-order motion: when first-order spirals were used, subjects reported a weaker MAE with MS than with SS. In contrast, the difference between the MAEs with SS and MS was slight when second-order motion was used as the adapting stimulus. These results may indicate that, contrary to previous suggestions (Chubb and Sperling, 1989 Proceedings of the National Academy of Sciences of the USA 86 2985 - 2989), first-order and second-order motion are not computed by a similar algorithm, ie the processing of second-order motion does not depend on extracting local edges while the processing of first-order motion does.
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