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Timeline of laboratory procedures to evaluate HF-HRV following stress (or neutral) imagery and smoking self-administration. Note: Baseline HF-HRV was collected over the 30 min prior to the start of the imagery procedure. Following the imagery procedure, HF-HRV was collected for a 5 min period (prior to cigarette presentation). During the self-administration period, HF-HRV was collected for a 15 min period during the smoking of the first cigarette.
