(2008), across just two sessions, and of Lee et al. (2003), with pathway signaling only seven smokers, and extend this reliability to self-reported reward (liking) and perception (how strong) ratings of smoking. Reliability may be poorer for smokers blind to brand (e.g., Perkins, Gerlach, Vender, Grobe, Meeker, & Hutchison, 2001), but our procedure of having smokers smoke their preferred brand in ad libitum and unblinded fashion is most similar to smoking in the natural environment, suggesting that such smoking is highly reliable. Reliability may also be different for smokers smoking conventionally, without any instrumentation (i.e., the CReSS device), although other research shows close similarity of topography between cigarettes smoked conventionally versus with the CReSS (Blank et al., 2009).

We generally did not see differences in the reliability of responses due to sex or dependence, indicating that reliability is comparable across different types of smokers. The only exception was poorer reliability of maximum puff volume (largest puff taken) in high versus low dependent men. This finding suggests that high dependent men may vary substantially across individual cigarettes in their maximum depth of puffing, perhaps inconsistent with the idea that their smoking behavior is more invariant (Shiffman & Paty, 2006). Further research is needed to confirm this individual difference. Future research should also explore other potential influences on the reliability of acute smoking responses, such as time of day (e.g., Grainge, Shahab, Hammond, O��Connor, & McNeil, 2009) and age (i.e.

, experimenting teens vs. dependent adults; Kassel et al., 2007). Contrary to a lack of individual differences in reliability of responses, our main focus, we did observe individual differences in the magnitude of responses to smoking. Specifically, total volume and maximum puff volume, as well as liking, were greater in high versus low dependent smokers (see Figure 2). These differences suggest that acute reinforcement (puff volume) and reward (liking) from smoking a cigarette may typically be greater in more dependent smokers. Such a result could have clinical implications as mean puff volume during a single cigarette has been shown to predict cessation outcome (Strasser et al. 2004). Total volume and maximum puff volume were also greater in men versus women, perhaps helping to explain sex differences in cotinine levels (e.

g., Gan, Cohen, Man, & Sin, 2008). Total volume and maximum puff volume dropped from Day 1 to subsequent days (Figure 1), suggesting that smokers may tend to smoke less from a single cigarette after the novelty of smoking upon arrival to a study session lessens. However, the high reliability of these measures indicates that any such decline across days is very comparable Entinostat between individuals.