Explicating Potential Opportunity Cost Reducing Male Heroin Abstainers’ Myopia In Intertemporal Decision-making

There was abundant of evidence indicated that substance addicts have intertemporal decision-making deficits.This group of people tend to choose "immediate rewards" such as euphoria generated by the use of addictive substances and the elimination of withdrawal symptoms,instead of the greater "long-term benefits" that can be obtained in terms of economy,interpersonal relationships and health after maintaining withdrawal,showed a myopic intertemporal decision-making tendency.This intertemporal decision-making deficits has been proved to play a significant role during the occurrence,development and withdrawal prognosis period of substance addiction.As a result,more and more researchers began to explore intervention methods which can effectively improve the intertemporal decision-making of substance addicts.However,in the existing intervention research in the field of addiction,whether it is Working Memory Training,Contingency Management or Episodic Future Thinking,substance addicts are required to actively pay a certain amount of effort and time.Considering the difficulties rooted in the actual daily abstinence treatment,the application value of the above traditional intervention methods is undoubtedly very limited.Moreover,the intervention effect in the existing intervention studies is not consistent.Outside the field of addiction,studies with non-addicts as subjects found that their preference for immediate options in intertemporal decision-making can be significantly reduced only by explicating the potential opportunity cost of intertemporal decision-making without additional efforts.This phenomenon is called the "hidden 0" effect.Based on the background mentioned before,this study mainly focused on the problem of "whether we can improve the intertemporal decision-making of substance addicts only by explicating the potential opportunity cost of intertemporal decisionmaking".Considering the situation of drug addiction in China,heroin abstainers were chosen as a representative sample of drug addicts.To speak specifically,in Experiment1,the classical monetary intertemporal decision-making task and related questionnaires were used to investigate the improvement of explicating potential opportunity cost on monetary intertemporal decision-making in heroin addicts,and the difference maybe exist in the improvement degree between heroin addicts and healthy control;In Experiment 2,the monetary delay discounting task and related questionnaires were used to test whether the results of Experiment 1 could be repeatedly verified in the "high reward,long-term" monetary intertemporal decision-making;Experiment 3 used the "heroin-money" cross-commodity delay discounting task to investigate whether the results of Experiment 1 and Experiment 2 could be further extended to crosscommodity decision-making which is more ecologically valid for heroin abstainers.Experiment 1 found that both heroin addicts(n = 30)and healthy control subjects(n = 29)chose less immediate monetary reward options in the decision-making situation with potential opportunity cost suggested than in situation without this suggestion,This result undoubtedly showed the improvement of intertemporal decision-making.However,there was no significant difference in the improving degree between these two groups.Moreover,there was no significant difference between the two groups in the overall chosen number of instant monetary reward options under the two decisionmaking situations;Experiment 2 found that compared with the decision-making situation without potential opportunity cost suggested,both heroin addicts(n = 27)and healthy control subjects(n = 27)showed significantly greater area under the delayed discounting curve(AUC)in the decision-making situation with potential opportunity cost suggested,showing the improvement of intertemporal decision-making.However,there was still no significant difference in the improving degree between these two groups.Being different from Experiment 1,heroin abstainers showed smaller AUC than healthy control subjects,explicating an abnormal intertemporal decision-making pattern;Experiment 3 found that the potential opportunity cost did not significantly improve the cross-commodity decision-making of heroin abstainers(n = 26).In a nutshell,the results of these three experiment showed that by explicating the potential opportunity cost can improve the monetary intertemporal decision-making of heroin abstainers rather than their "heroin-money intertemporal cross-commodity decision-making".It is suggested that the potential opportunity cost may broaden the time horizon both of heroin addicts and healthy control subjects,and activate their "farsighted system" of intertemporal decision-making more,this may reduce the subjective value of immediate monetary option for deciders,and finally encourage them to choose more delay monetary reward rather than immediate monetary reward,so as to improve their monetary intertemporal decision-making.There was no significant difference in the improving degree of monetary intertemporal decision-making between these two groups.Considering the intertemporal decision-making deficits of heroin abstainers,it implied that only by explicating the potential opportunity cost is not enough to eliminate the gap of intertemporal decision-making between heroin abstainers and healthy control.At the same time,it also indirectly suggests that the abnormal time horizon ccould not fully explain the intertemporal decision-making deficits of substance addicts.It is also suggested by this study that explicating the potential opportunity cost couldn’t significantly improve the "heroin-money" cross-commodity decision-making of heroin abstainers,which may be due to the relative higher subjective value of heroin than money as an immediate reward for this group of people,so it is difficult to be reduced.This result also reflects the necessity of increasing the use of "heroin-money" crosscommodity delay discounting tasks in the field of substance addiction.It is necessary to use female samples in future research to further increase the ecological validity of the conclusions of this study.