Beverly Anusionwu, a smoker for three decades who favors Maverick menthols, was enticed to the small lab inside the University of Pittsburgh's psychology department by an ad promising free cigarettes and a few bucks for her time.

She spent a couple of hours on a recent morning answering questions about her medical history and undergoing a battery of cognitive tests. When she finished, researchers handed her five gray packs of cigarettes unlike any she had ever seen, along with instructions to report back daily on how much she was smoking and whether her cravings and moods changed.

"Spectrum menthol," Anusionwu said, reading the label aloud. "All right, then. I guess nicotine is nicotine."