Vol.:(0123456789) 1 3 Animal Cognition https://doi.org/10.1007/s10071-019-01315-9 ORIGINAL PAPER On the transfer of spatial learning between geometrically diferent shaped environments in the terrestrial toad, Rhinella arenarum María Inés Sotelo 1  · José Andrés Alcalá 2  · Verner P. Bingman 3  · Rubén N. Muzio 1,4 Received: 19 April 2019 / Revised: 23 September 2019 / Accepted: 29 September 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract When trained in a rectangular arena, some research has suggested that rats are guided by local features rather than overall boundary geometry. We explored this hypothesis using the terrestrial toad, Rhinella arenarum, as a comparative contrast. In two experiments, toads were trained to fnd a water-reward goal location in either a featureless rectangular arena (Experiment 1) or in a rectangular arena with a removable colored feature panel covering one short wall (Experiment 2). After learning to successfully locate the water reward, probe trials were carried out by changing the shape of the arena into a kite form with two 90°-angled corners, and in the case of Experiment 2, also shifting the location of the color panel. The results of Experi- ment 1 indicated that the toads, in contrast to rats, relied primarily on overall shape or boundary geometry to encode the location of a goal. Under the probe conditions of the altered environmental geometry in Experiment 2, the toads seemed to preferentially choose a corner that was generally correct relative to the feature panel experienced during training. Together, the data of the current study suggest that toads and rats difer in the strategies they employ to represent spatial information available in a rectangular arena. Further, the results support the hypothesis that amphibians and mammals engage diferent neural mechanisms, perhaps related to diferent evolutionary selective pressures, for the representation of environmental geometry used for navigation. Keywords Amphibians · Spatial learning · Shaped environments · Boundary geometry Introduction Although there is considerable evidence demonstrating the importance of environmental geometry for spatial learn- ing, there remain questions on the nature of its encod- ing and how it may be related to other types of spatial information (see Cheng et al. 2013, for a review of current theories). In his watershed study on geometry and naviga- tion in rats, Cheng (1986) showed that rats made a system- atic error when searching for buried food in a rectangular arena with diferent local cues. In fact, even though the local cues (visual and olfactory) predicted the location of the food with 100% certainty, animals systematically relied on the rectangular (boundary) geometry of the test arena, which could only predict the location of the food with 50% accuracy. Since then, similar studies have been carried out in a variety of diferent species, ranging from fsh and amphibians to other mammalian species, under varying conditions and yielding somewhat inconsistent outcomes. For instance, fndings from toads (Sotelo et al. 2015, 2017), chicks (Vallortigara et al. 1990), pigeons (Kelly et al. 1998), rats (Benhamou and Poucet 1998), young and adult humans (Hermer and Spelke 1994, 1996; Hermer-Vazquez et al. 1999; Newcombe et al. 2010; Sturz et al. 2011) and even ants (Wystrach and Beugnon 2009; Wystrach et al. 2011) show preferential use of boundary geometry to locate a goal in some spatial learning tasks. * Rubén N. Muzio rnmuzio@gmail.com 1 Instituto de Biología y Medicina Experimental (IBYME- CONICET) and Facultad de Psicología, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina 2 Departamento de Psicología, Universidad de Jaén, Jaén, Spain 3 Department of Psychology and J.P. Scott Center for Neuroscience, Mind and Behavior, Bowling Green State University, Bowling Green, USA 4 Grupo de Aprendizaje y Cognición Comparada, Laboratorio de Biología del Comportamiento, Instituto de Biología y Medicina Experimental (IBYME-CONICET), Vuelta de Obligado 2490, CP 1428 Buenos Aires, Argentina