Backward blocking in honeybees.

Three experiments with foraging honeybees were designed to study the effect of experience with A on responding to B after AB+ training. In the first experiment, responding to B was the same whether the AB+ training was preceded or followed by A+ training. In the second experiment, responding to B after AB+ training was less in animals that also had A+ training than in control animals that were equally often reinforced in the absence of A; whether the A+ training preceded, was concurrent with, or followed the AB+ training made no difference. In the third experiment, responding to B after AB+ training was less when the AB+ training was followed by A+C- training than when it was followed by C+/A- training. These results, like those of some recent vertebrate experiments, take us beyond the traditional explanation of blocking in terms of impaired conditioning of B on AB+ trials and support the suggestion that the mechanism, still poorly understood, may nevertheless be a relatively simple one.