Ants in rectangular arenas

Abstract

Although spatial cognition is studied by neuroscientists, psychologists, biologists and computer scientists, it suffers from a lack of integrative studies. The topic of geometry of space for instance, has been studied since twenty years only in vertebrates and only in artificial and visually poor environ-ments. But recently, similar results have been obtained with ants, supporting the recent idea of global matching. Contrary to the other theories about geometry, global matching is parsimonious, testable in natural conditions and makes sense in an ecological context. Here, further investigations into the data obtained in ants describe and support a new concept for the global matching theory: the Mismatch Tolerance Threshold (MTT). This new idea can be tested in other species and we stress the importance of considering the whole paths displayed by the animals in future experiments. How animals encode the visual shape of their environment has drawn an increasing interest since the seminal work of Cheng. 1 This topic is now studied across many vertebrate species 2 and several theories on how the geometry of space is extracted and encoded are debated. 3 However, most of those studies were conducted in artificial rectangular arenas and little attention has been paid to the relevance of such spatial information in nature. 4 Recently, Wystrach and Beugnon 5 used Cheng's paradigm 1 to test a visual ant species (Gigantiops destructor) in the typical rectangular arena, a première among invertebrates. The results obtained with ants are similar to those of vertebrates but, without summoning theories about geometry, can be parsimoniously explained by a global matching hypothesis. 5 The concept of global matching is simple and requires no feature extraction: the agent relies on a panoramic view previously stored at the goal location, and moves in order to minimize the mismatch between its current view and the memorized view. When the two views match, the goal is reached. Global matching can not only explain the results obtained in rectangular arenas 6 but can also be applied in natural conditions 7 (Wystrach et al., in preparation).