Considerations on models of movement detection

A general characterization of multi-input movement detection models is given in terms of the Volterra series formalism. When nonlinearities of order higher than the second are negligible, an n-input system can be decomposed into a set of 2-input systems, summing linearly. For a (symmetrical) 2-input system which has significant nonlinearities only up to the second order, the correlation model is its most general expression, if the infinite time average of the output is taken. Specific observations from optomotor experiments (e.g. phase invariance and contrast frequency dependence) can be interpreted in a general way in terms of properties of the Volterra representation. We would like to thank Mr. E. Buchner, Dr. K. Kirschfeld, Mr. B. Pick, Mr. Ch. Wehrhahn and especially Dr. K. G. Götz for critical remarks. Thanks are also due to Dr. B. Rosser for reading and to Mrs. I. Geiss for typing the English manuscript