Self Control in Honeybees

Self control means choosing a larger delayed reward over a smaller immediate reward. The opposite of self control is impulsiveness. Vertebrate animals (mostly rats, pigeons, and humans) studied have been notorious for impulsivity. We (Jennifer Pena, Melanie Porter, Julia Irwin, and I) tested honeybees on self control to decipher between two functional explanations for cross-species differences in self control. One hypothesis we call the metabolic hypothesis. It says that impulsiveness is adaptive for creatures with faster metabolisms -- they need food now rather than later. The other hypothesis we call the ecological hypothesis. This says that self control or its lack has been shaped by the ecological conditions under which animals evolved. Both hypotheses stem from Alexandra Logue.

Honeybees have fast metabolisms. By the metabolic hypothesis, they should be impulsive. But they forage mostly for the long term good of their hive, and not for their own immediate needs. By this 'ecological analysis', they should show lots of self control.

We gave bees choices like this:

On the left is a much sweeter reward than on the right. But to get to it, they have to hover for 5 s over the coloured paper before we removed the glass over it. (The rewards were not coloured. We put a piece of poster paper in the reward dish for the photo session.)

Three experiments with different procedures showed that bees exhibit lots of self control. The ecological hypothesis is upheld, and the metabolic hypothesis can be ruled out.

Here is a taste of the results:

The experimental group was offered the classic choices of self control on the first day. They preferred a large delayed reward over a small immediate reward. On the second day, they chose between a large non-delayed reward and small non-delayed reward. The seeming improvement from day 1 to day 2 is most likely due to practice at the task. That is beacuse a similar pattern was found for bees offered both choices with no delay throughout (Control). They too improved on day 2, to a similar extent.


The results contradict the metabolic hypothesis, but a much clearer formulation of the ecological hypothesis is needed. As it stands at the moment, the formulation is too vague to allow precise quantitative predictions.

 

Reference

Cheng, K., Peña, J., Porter, M.A., & Irwin, J.D. (2002). Self control in honeybees. Psychonomic Bulletin & Review, 9, 259-263. pdf


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