The Use of Optic Flow Information in Insect Vision and Navigation

Mandyam Srinivasan and Shaowu Zhang

Abstract:	A glance at a fly evading a rapidly descending hand, or orchestrating a flawless landing on the rim of a teacup would convince even the most sceptical observer that many insects are not only excellent fliers and navigators, but also possess visual systems that are fast, reliable, precise, and exquisitely sensitive to motion. It is no wonder, then, that there has been considerable interest in trying to fathom how insects detect, evaluate and use motion cues in their daily lives. Unlike vertebrates, insects have immobile eyes with fixed-focus optics. Therefore, they cannot infer the distance of an object from the extent to which the directions of gaze must converge to view the object, or by monitoring the refractive power that is required to bring the image of the object into focus on the retina. Furthermore, compared with human eyes, the eyes of insects are positioned much closer together, and possess inferior spatial acuity. Therefore, even if an insect possessed the neural apparatus required for binocular stereopsis, such a mechanism would be relatively imprecise and restricted to measuring ranges of only a few centimetres (Collett and Harkness 1982; Horridge 1987; Rossell 1983; Srinivasan 1993). Not surprisingly, insects have evolved alternative strategies for visual guidance and navigation. Some of these strategies are outlined below, and references to more complete accounts are provided.
Published in:	Proceedings of the 60th Annual Meeting of The Institute of Navigation (2004) June 7 - 9, 2004 Dayton Marriott Hotel Dayton, OH
Pages:	157 - 165
Cite this article:	Srinivasan, Mandyam, Zhang, Shaowu, "The Use of Optic Flow Information in Insect Vision and Navigation," Proceedings of the 60th Annual Meeting of The Institute of Navigation (2004), Dayton, OH, June 2004, pp. 157-165.
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