Tortoises develop and overcome position biases in a reversal learning task
The capability of animals to alter their behaviour to novel or familiar stimuli, or behavioural flexibility, is strongly associated with their ability to learn in novel environments. Reptiles are capable of learning complex tasks, and offer a unique opportunity to study the relationship between visual proficiency and behavioural flexibility. The focus of this study was to investigate the behavioural flexibility of red-footed tortoises and their ability to perform reversal learning. Reversal learning involves first learning a visual discrimination, after which the previously rewarded cue is reversed and then subjects perform the visual task with new reward contingencies. Red-footed tortoises were required to learn the visual cues within a Y-maze, a complex task that required coordination. Once subjects learned the visual discrimination, tortoises were required to successfully learn 4 reversals. Compared to acquisition learning, tortoises required significantly more trials to reach criterion (80% correct) in the first reversal, indicating the difficulty of unlearning the positive stimulus initially presented in acquisition. Nevertheless, subsequent reversals required similar number of sessions as the initial acquisition stage, demonstrating that reversal learning improves up to a point. All subjects tested developed a turning bias within the Y-maze that was absent prior to the acquisition task, but were able to exhibit reversal learning despite this persistent turning bias. The results herein demonstrate that red-footed tortoises exhibit behavioural flexibility in a learning task requiring coordination between visual cues and maze navigation. Improving performance while simultaneously overcoming a persistent turning bias provides us greater insights into the advanced cognitive abilities of tortoises.
Natural Sciences and Engineering Research Council of Canada, Award: RGPIN-2014-05814