When methamphetamine replaced crack as the great drug scourge in the United States, Dr. Hart brought meth addicts into his laboratory for similar experiments — and the results showed similarly rational decisions. He also found that when he raised the alternative reward to $20, every single addict, of meth and crack alike, chose the cash. They knew they wouldn’t receive it until the experiment ended weeks later, but they were still willing to pass up an immediate high.

These findings made Dr. Hart rethink what he’d seen growing up, as he relates in his new book, “High Price.” It’s a fascinating combination of memoir and social science: wrenching scenes of deprivation and violence accompanied by calm analysis of historical data and laboratory results. He tells horrifying stories — his mother attacked with a hammer, his father doused with a potful of boiling syrup — but then he looks for the statistically significant trend.

Yes, he notes, some children were abandoned by crack-addicted parents, but many families in his neighborhood were torn apart before crack — including his own. (He was raised largely by his grandmother.) Yes, his cousins became destitute crack addicts living in a shed, but they’d dropped out of school and had been unemployed long before crack came along.

“There seemed to be at least as many — if not more — cases in which illicit drugs played little or no role than were there situations in which their pharmacological effects seemed to matter,” writes Dr. Hart, now 46. Crack and meth may be especially troublesome in some poor neighborhoods and rural areas, but not because the drugs themselves are so potent.

“If you’re living in a poor neighborhood deprived of options, there’s a certain rationality to keep taking a drug that will give you some temporary pleasure,” Dr. Hart said in an interview, arguing that the caricature of enslaved crack addicts comes from a misinterpretation of the famous rat experiments.

“The key factor is the environment, whether you’re talking about humans or rats,” Dr. Hart said. “The rats that keep pressing the lever for cocaine are the ones who are stressed out because they’ve been raised in solitary conditions and have no other options. But when you enrich their environment, and give them access to sweets and let them play with other rats, they stop pressing the lever.”