Abstract: Animal cognition provides valuable insight for understanding behavior and its evolution. Cognitive ability, or the way animals process and use information from their environment, widely varies across taxa and can be influenced by multiple selective pressures such as social complexity and/or the environment. Much of research today in animals tests the cognitive abilities of individuals to represent the cognitive traits of a species as a whole; however, quantifying individual differences on multiple cognitive domains within a species can reveal specific patterns between cognition, behavior, and fitness consequences. To test the possible differences in cognitive structure based on social complexity within a single species, we designed and implemented a cognitive test battery consisting of four associative learning tasks and one memory task for the paper wasp species Polistes fuscatus. This species is unique in that it not only possesses the complex ability of individual recognition, but also displays geographic variation in that social cognitive skill: populations in Michigan (MI) can recognize individuals’ faces, while populations in Pennsylvania (PA) cannot. Moreover, there is an obvious phenotypic difference between the populations where MI wasps have unique facial markings, whereas PA wasps have much less variation. We reared and tested twenty wasps from three treatment groups: MI only, PA only, and MI-PA crossrear. Each wasp underwent five tests in random order: face learning, color learning, reversal learning, odor learning, and odor memory. The learning tasks tested the wasps’ ability to discriminate between two images of MI wasp faces, colors, and odors. For the reversal learning we switched the color stimuli based on the initial test, and the odor memory test was conducted one week after the initial test. Our results show that the order of the cognitive battery influenced the performance of the wasps. Test order alone did not influence cognitive performance for all wasps in the same pattern, but differently depending on the treatment group. This test order interaction limits our ability to compare the non-social cognitive abilities between MI and PA wasps as initially intended. We suggest improvements to our experimental design for future work and demonstrate promise in the cognitive battery as a method for measuring individual differences in cognitive structure within a species and across taxa. Although geographic variation in phenotypes within a species is quite common, the relatively understudied geographic variation in cognitive ability can provide valuable insight for understanding how cognition can evolve and diversify across populations.
