A new training procedure for studying discrimination learning in fish

The study of animal cognition and its neurobiological bases often requires the adoption of associative learning procedures. Though fish are increasingly being used as a model system in behavioral neuroscience, the availability of adequate learning protocols can be a limiting factor in this field of research. This study describes a novel training procedure to explore visual discrimination in fish. Subjects were singly housed in rectangular tanks. At intervals, two stimuli were introduced at opposite ends of the tank and food was delivered near the stimulus to be reinforced. Time spent near positive stimulus in probe trials was taken as a measure of discrimination performance. To validate the method, we replicated two published studies that used operant conditioning to investigate the mechanisms of numerical discrimination in mosquitofish. Our data indicate a complete overlap of the results obtained using the two different methods. The pros and cons of the new procedure are discussed in respect of traditional associative learning paradigms.