Scaling relative incentive value in honey bees, Apis mellifera

Abstract

Reward downshifts in honey bees, Apis mellifera, result in a suppression of behavior that parallels mammalian frustration in response to reward downshift. Consistent with Weber’s Law, rats drinking sucrose that are trained with a 32 % sucrose solution and downshifted to a 4 % solution show a disruption in drinking based on the ratio discrepancy between the solutions, known as the “ratio scaling” property. The present experiment explored whether bee reward downshifts also exhibit ratio scaling, or instead depend upon absolute differences between solutions. Groups of bees were trained with a variety of sucrose solutions, then downshifted to smaller solutions that shared the same absolute differences or the same ratios. Results indicated that for bees, the disruption of consummatory behavior is determined by the absolute difference between solutions. A second experiment confirmed that these results are unlikely to be due to sensory adaptation. These results are the first to highlight a fundamental difference in the way bee and mammalian reward comparisons are made.