Fig. 4

Schematic overview of (A) the experimental setup and (B) the learning tasks tested. (A) The rotating screen apparatus consisted of a vertical rotatable screen mounted on a stand. Hangers displaying the stimuli of the respective learning tasks (5 × 5 cm squares) were attached to the screen at various positions via hooks. Each hanger featured a small landing platform where bees could collect reinforcements during conditioning. (B) Overview of the learning tasks. In the first phase of reversal learning, stimulus A+ was rewarded with sucrose solution, whereas stimulus B− was punished with a bitter quinine solution. In the second phase, the reward contingencies of the first phase were reversed so that stimulus A− was punished and B+ rewarded. The stimuli used were cut from HKS-3N and HKS-68N cardboard, which appeared yellow and greenish yellow to the human eye, respectively. Half of the bees were initially trained with HKS-3N as stimulus A and HKS-68N as stimulus B, and vice versa for the other half. In the negative patterning task, bees had to learn that single stimuli C+ and D+ were each rewarded with a sucrose solution, while their compound CD- was not reinforced. The single stimuli used were checkerboard squares cut from HKS-26N cardboard (C+, pink) and HKS-44N (D+, blue) presented on a gray background, which was achromatic to the bees (HKS-92N). The compound stimulus CD- combined squares from HKS-26N and HKS-44N cardboard.