For the experiments, a pair of mice — one male, one female — was kept in one cage and five "intruder" mice were kept in a separate cage. The female mouse was temporarily removed, and an intruder mouse was introduced in its place, triggering an aggressive response by the 'home' male mouse. Aggressive behavior included tail rattle, an aggressive sideways stance, boxing and biting.

The home mouse was then trained to poke a target with its nose to get the intruder to return, at which point it again behaved aggressively toward it. The home mouse consistently poked the trigger, which was presented once a day, indicating it experienced the aggressive encounter with the intruder as a reward.

The same "home" mice were then treated with a drug that suppressed their dopamine receptors. After this treatment, they decreased the frequency with which they instigated the intruder's entry.