The measure is derived by transforming scores on the Minnesota Nicotine Withdrawal Scale (where higher values signify more withdrawal), the Affect-based Withdrawal Scale (higher values signify a worse emotional state), Questionnaire for Smoking Urges (higher values indicate more craving), and modified Cigarette Evaluation Questionnaire (mCEQ, higher values indicate greater subjective effects of smoking on mood, hunger, physiology) into standard z-scores, thus giving each scale a mean of 0 and standard deviation of 1. Withdrawal and craving scores were re-poled (inversing the sign), and scales were averaged for each subject. The resulting composite quantified the subjective state response to cigarette smoking, larger values indicating less withdrawal, less craving, and larger effects on the mCEQ. The difference therein between the research cigarettes containing nicotine and those containing almost no nicotine quantified the subjective state response to nicotine.

This is a diagnostic group (i.e., no diagnosis of schizophrenia), defined independently from this study.

Sampling Research Cigarettes: Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.

Total of all reporting groups

This is a diagnostic group (i.e., no diagnosis of schizophrenia), defined independently from this study.

Sampling Research Cigarettes: Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.

Participants sample 4 cigarettes of type A and 4 cigarettes of type B in a double-blind manner and indicate for each cigarette if they think it is of type A or B. Two reference trials with cigarette type unblinded will be performed before the first and fifth sample cigarette. For each sampled cigarette, the score is either 1 (correct) or 0 (incorrect). Discrimination accuracy is calculated by averaging the eight scores for each participant.

One smoker with schizophrenia did not complete the study session in which this measurement was obtained, but completed the rest of the study.

In the Ad Libitum Smoking Session, participants can smoke as many research cigarettes (all very-low-nicotine-content) as they wish. The propensity to maintain smoking despite the absence of nicotine was quantified by subtracting the number of cigarettes smoked in the last two hours from that in the first two hours of the session. Smaller difference values indicate that smoking was upheld by very-low-nicotine-content cigarettes.

One smoker with schizophrenia and one smoker without schizophrenia did not complete the study session in which this measurement was obtained but completed the rest of the study.

The measure is derived by transforming scores on the Minnesota Nicotine Withdrawal Scale (where higher values signify more withdrawal), the Affect-based Withdrawal Scale (higher values signify a worse emotional state), Questionnaire for Smoking Urges (higher values indicate more craving), and modified Cigarette Evaluation Questionnaire (mCEQ, higher values indicate greater subjective effects of smoking on mood, hunger, physiology) into standard z-scores, thus giving each scale a mean of 0 and standard deviation of 1. Withdrawal and craving scores were re-poled (inversing the sign), and scales were averaged for each subject. The resulting composite quantified the subjective state response to cigarette smoking, larger values indicating less withdrawal, less craving, and larger effects on the mCEQ. The difference therein between the research cigarettes containing nicotine and those containing almost no nicotine quantified the subjective state response to nicotine.

One smoker with schizophrenia and one smoker without schizophrenia did not complete the study session in which this measurement was obtained. One additional smoker with schizophrenia did not complete the subjective state measurements but completed all other aspects of the session.

This is a diagnostic group (i.e., no diagnosis of schizophrenia), defined independently from this study.

Sampling Research Cigarettes: Participants sample two research cigarettes, which differ in typical tobacco smoke constituents such as tar, nicotine, carbon monoxide, etc. In the Cigarette Discrimination Session, participants sample both types of cigarettes repeatedly, guess their identity (A or B) with regard to reference cigarettes, and rate their subjective effects. In the Ad Libitum Smoking Session, participants can smoke one of these cigarette types as much or as little as they like for eight hours.