International Journal of Comparative Psychology

The ability to discriminate four individual conspecifics by olfactory cues in laboratory mice was investigated. Adult male mice of the CD-I outbred strain were water deprived and placed in a Plexiglas four-arm maze, twice a day, five days a week. Subjects were assigned to two groups: Training and Control. Training mice were trained by water reinforcement (a drop of water) to choose the maze's arm containing the sawdust of one of four donors (adult males, same strain), while for Control mice the association between sawdust and reinforcement was continuously varied. Data collected during three weeks showed that Training mice made significantly fewer errors in finding the water than Control mice, thus confirming the results of previous experiments based on a two-way choice that proved mice to be able to discriminate conspecifics individually by olfactory cues.