Addiction, Affliction, or Avocation

Anthony and Jeff consider the plight of mice in a cage, given the opportunity to drink clean, natural water, or water laced with illicit drugs. Is their choice dependent on the pure addictive properties of the drugs, each individual mouse's brain chemistry, or a simple lack of other interesting things to do? What does this experiment tell us about how we approach drug use in humans? And why is there always a 7-11 involved?