Interesting study, by Dr. Carl Hart, written up in the New York Times:
At the start of each day, as researchers watched behind a one-way mirror, a nurse would place a certain amount of crack in a pipe — the dose varied daily — and light it. While smoking, the participant was blindfolded so he couldn’t see the size of that day’s dose.
Then, after that sample of crack to start the day, each participant would be offered more opportunities during the day to smoke the same dose of crack. But each time the offer was made, the participants could also opt for a different reward that they could collect when they eventually left the hospital. Sometimes the reward was $5 in cash, and sometimes it was a $5 voucher for merchandise at a store.
When the dose of crack was fairly high, the subject would typically choose to keep smoking crack during the day. But when the dose was smaller, he was more likely to pass it up for the $5 in cash or voucher.
“They didn’t fit the caricature of the drug addict who can’t stop once he gets a taste,” Dr. Hart said. “When they were given an alternative to crack, they made rational economic decisions.”