Summary
The ability to learn a simple discrimination between two colors yellow and blue, was measured in eleven species of social bees and marks were attributed to each species on the basis of the mean number of correct choices, number of corret choices after the last error, and number of responses during extinction. Several criterions for attributing such marks are presented. The training procedure included Shaping of the response of "landing" on the apparatus, differential reinforcement associated with yellow, for five bees, or blue for five other bees of each species, and extinction by removal of food. Each bee was trained individually through 70 choices between two small colored dishes and then submitted to extinction until 30 minutes pause was made.