, 2008). The placebo solution was placed in empty Nicotrol bottles to allow double-blind administration. Attention Measures Executive attention was measured using a Rapid Serial Visual Presentation (RSVP) selleck chemical task and the Attention Network Test (ANT). The RSVP task can assess the attentional blink phenomenon in which two target words (T1 and T2) are presented with a varying number of intervening distracter words (lags). Participants are typically accurate at reporting T1; however when T2 follows T1 within 500 ms (early lags), identification of T2 is impaired, as if our attentional system ��blinked�� (Raymond, Shapiro, & Arnell, 1992). The RSVP task used in this study has been described (Heinz et al., 2007). Briefly, participants completed 48 trials, each of which contained 16 individually presented words (T1, T2, and 14 distracters).

Target words were selected from a list of commonly used nouns whereas the 14 distracter words were less commonly used nouns. Across sessions, no word was presented more than once; all words were unrelated to smoking and emotionally neutral. The task lasted 10�C15 min. Correct reporting of T1 measured alerting attention; identification of T2, especially at early T1�CT2 lags, assessed executive attention. The ANT is a combination of a cued reaction time task and a flanker task (Fan, McCandliss, Sommer, Raz, & Posner, 2002). Participants completed 2 blocks of 96 trials. For each trial, the target was an arrow presented above or below a fixation cross on the monitor. Participants indicated whether the arrow was pointing left or right.

The central arrow was flanked on either side by two arrows pointing in the same direction (congruent cue), the opposite direction (incongruent cue), or by straight lines. Subtraction of response times to congruent cues from incongruent cues yielded a measure of executive attention. Alerting attention was assessed by two warning conditions that cued the onset of the target arrow: fixation cross only (no cue) or an asterisk above and below the fixation cross (double cue). Subtraction of response time to double cue from no cue yielded a measure of alerting attention (Fan et al., 2002). Alerting attention was also measured using a 6-min CPT (Myers et al., 2008). Participants viewed letters displayed on a monitor one at a time in rapid succession (100 ms presentation, 600 ms interstimulus interval) and pressed a button when they saw the letter ��X.

�� There were 100 targets and 400 nontargets presented each session. To make the task more challenging, we used a degraded version in which 30% of the pixels of each letter were absent. Dependent variables were correct target responses, errors of commission, Batimastat adjusted target responses (target responses minus errors of commission), mean response time, and response time variability.