CAN 3-SPINED STICKLEBACKS LEARN WHEN TO DISPLAY - REWARDED DISPLAYS

Learning when and how to perform displays could be important for the d evelopment of normal aggressive behaviour. This paper examines the eff ects of associating threat displays with the disappearance of an oppon ent in three-spined stickleback fish, Gasterosteus aculeatus. It was p redicted that making the opponent 'go away' each time the test subject displayed should reward the use of head-down threat: trained fish sho uld increase the probability of threat relative to other aggressive ac ts. Threat became more common and was more quickly used by rewarded fi sh. Continuous-time Markov chain models of the sequence of actions sho wed that the relative chance of changing from other acts to the threat display was increased in reinforced fish. However, none of the change s was outside the range of normal variation seen in untrained individu als.