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Methamphetamine users (MAU) exhibit an exaggerated bias for immediate rewards that reflects a restricted time horizon, where outcomes in the future are excessively discounted. An accumulating literature indicates that time in the future shares features with other dimensions of psychological distances including time in the past, probability, and social distance, suggesting that bias for immediacy may be reducible to a more general restriction of psychological horizon. The purpose of the present study was to explore generalized restricted psychological horizon in active MAU by assessing future, past, probability, and social discounting. Compared with nonusing controls, MAU preferred psychologically proximal outcomes, resulting in higher rates for all types of discounting, which supports the conceptualization that MAU insufficiently integrate outcomes of psychological distance (i.e. in the future, the past, probabilistic, for others) into the valuation of current behavioral alternatives. The present results are suggestive of a more fundamental process of problematic decision-making associated with methamphetamine use, indicating the necessity of more comprehensive approaches to address the generalized limitations of restricted psychological horizon.

Nineteen nicotine-deprived cigarette smokers received monetary rewards for each minute they chose not to initiate smoking in 2-h laboratory sessions followed by a 30-min period of enforced abstinence from smoking. Reinforcer amounts were delivered according to one of three schedules: increasing, decreasing, and constant. Relapse time (time until first cigarette) was shortest in the decreasing condition, longest in the increasing condition, and intermediate in the constant condition. All differences were significant except in the constant-decreasing comparison. The relationships between a battery of baseline assessments and relapse times were examined. Relapse times were predicted by delay-discounting coefficients (k) for $10 and $1000 in money and for $1000 of cigarettes. Relapse times were also predicted by the number of cigarettes smoked daily and a Wisconsin Card Sorting Test score. Performance on the Stroop Task and the Fagerström Test for Nicotine Dependence differentiated participants dichotomized into those who relapsed 'earlier' in sessions versus those who first smoked 'later'. The variability in some scores from smoking-urges and affect questionnaires administered after smoking-room sessions was explained by measures related to in-session nicotine intake. Results are discussed as they relate to contingency-management procedures, predictors of relapse, and the competing neurobehavioral decision systems theory of addiction.

One of the hallmarks of drug addiction is a limitation of the temporal horizon of events that affect the behavior of drug users. The purpose of this experiment was to examine the time period over which smoking was influenced by an earlier opportunity to smoke. Baseline sessions measured how much was smoked in a current opportunity when it was preceded by a 2-h wait time in which no smoking was allowed. After the baseline phase, we examined the effects of temporal distance when an earlier opportunity to smoke (upon completion of a fixed ratio 100) preceded current smoking (upon completion of a progressive ratio). Temporal distance between these two opportunities to smoke was varied from 0 to 120 min. We found that current smoking for the group was reduced from baseline levels when the temporal distance was 0 min. At temporal distances ranging from 30 to 90 min, the individual's smoking returned to levels that were similar to baseline. Breakpoints were also a function of earlier smoking, and latencies to first puff of the session followed a similar trend. These findings provide evidence of the limited temporal horizons related to smoking bouts of smokers and may provide a useful measure for metabolism differences across populations. In addition, we suggest that the quantitative description of satiety provided by our procedures may validate drug replacement therapies involved in cessation treatments.