Muszynski and Couvillon (see record 2020-37265-001) built upon their previous findings that honeybees can learn the relation among triads of trial-unique visual stimuli. In this new work, they showed that bees encountering trial-unique sets of three or four visual stimuli chose the correct stimulus at above-chance levels, replicating their previous findings and extending them to four-choice displays. In the first experiment, the bees’ performance with triads of stimuli was unaffected by whether the correct choice was patterned or solid, or whether the stimuli shared a common color. A control group in this experiment encountered a categorical discrimination problem with two stimuli. This latter group of bees easily learned the discrimination and made a lower proportion of errors than bees solving the oddity problem, suggesting that the bees did not perceive the oddity task as a discrimination problem. The possibility that bees solved the oddity problem as a categorical discrimination was further examined in a second experiment. In that experiment, one group of bees encountered quartets of disks in combinations of solid color and two-color disks, and another group encountered only two-color disks. The authors expected that the addition of an irrelevant category (solid or two-color disk) would make the odd stimulus more discriminable, and, therefore, improve performance in that group compared with the group that encountered only two-colored disks. Their expectation was confirmed: Bees that encountered stimuli with a categorical difference, even though the category was irrelevant to which disk (of four) was odd, averaged more correct choices (average .67 vs. .47 across 15 trials; .25 expected by chance) and reached a higher terminal level of performance than bees that encountered only two-color disks (nearing .90 vs. around .50 correct, Trials 14 –16, solid and pattern group vs. pattern-only group, respectively). (PsycInfo Database Record (c) 2020 APA, all rights reserved)