Steven Kelty had been addicted to crack cocaine for 32 years when he tried a different kind of treatment last year, one so basic in concept that he was skeptical.
He would come to a clinic twice a week to provide a urine sample, and if it was free of drugs, he would get to draw a slip of paper out of a fishbowl. Half contained encouraging messages — typically, “Good job!” — but the other half were vouchers for prizes worth between $1 and $100.
