International Journal of Comparative Psychology

Previous research looking at expectancy in animals has used various experimental designs focusing on appetitive and avoidance behaviors. In this study, honey bees ( Apis mellifera ) were tested ina series of three proboscis extension response (PER) experiments to determine to what degree honey bees’ form a cognitive-representation of an unconditioned stimulus (US). Tthe first experiment, bees were presented with either a 2 sec. sucrose US or 2 sec. honey US appetitive reward and the proboscis-extension duration was measured under each scenario. The PER duration was longer for the honey US even though each US was presented for just 2 sec.   Honey bees in the second experiment were tested during extinction trials on a conditioned stimulus (CS) of cinnamon or lavender that was paired with either the sucrose US or honey US in the acquisition trials.  The proportion of bees showing the PER response to the CS was recorded for each extinction trial for each US scenario, as was the duration of the proboscis extension for each bee.  Neither measure differed between the honey US and sucrose US scenarios,  In experiment three, bees were presented with a cinnamon or lavender CS paired with either honey US or sucrose US in a set of acquisition trials, but here the US was not given until after the proboscis was retracted. The PER duration after the CS, and again subsequent after the US, were recorded. While the PER duration after the US was longer for honey, the PER duration after the CS did not differ between honey US and sucrose US.