Jim remembered one time in school that there was this scientist who trained dogs to salivate to the sound of a bell, so he wanted to try this experiment on Dwight.
However, Jim wanted to see if Dwight would eat a mint every time he heard Jim's computer turn on.
When Jim first turned his computer on, he was surprised that the experiment worked and that Dwight asked for a mint. Eventually it became natural for Dwight to always want a mint, every time Jim's computer turned on.