Behaviour 2019
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Referenced-based evaluations of floral rewards in bumblebees
Claire T Hemingway, Felicity Muth. University of Texas at Austin, Austin, TX, United States

Models of animal decision-making often assume that individuals can easily assess the absolute value of different options. However, we know that rewards are often evaluated according to reference points. These reference-based evaluations have the potential to create contrast effects in which a discrepancy between expectations and rewards can lead to an exaggerated response of aversion or preference. Contrast effects may be particularly important for bumblebees foraging on a broad range of flower types that vary in both their signals and their nectar rewards. While contrast effects are often assumed to be purely sensory, we know from research with humans that expectations may affect value perception. We manipulated bees’ expectations of stimuli quality through prior experience, before downshifting the reward to induce incentive contrast. With prior experience of a floral signal and higher expectations of its quality, we found that bees were more sensitive to a downshifting of its rewards than with a novel signal. We argue that these reference-dependent evaluations may play an important role in floral evolution and have the potential to influence community dynamics.