Intertemporal choice, risk preferences, and social dominance: an experimental investigation

Most decisions in everyday life require to take into consideration both time and uncertainty. Individuals often face intertemporal choices, i.e. decisions between smaller immediate options and larger delayed options, and probabilistic choices, i.e. choices between smaller certain rewards and larger risky ones. Temporal discounting refers to the devaluation of a reward as a function of its delay, whereas probability discounting refers to the devaluation of a reward as the odds against its receipt increases. Since both phenomena are well described by hyperbolic discounting functions, several authors have hypothesized that there is a relationship between delay tolerance and risk propensity, although there is still no agreement either on the existence of such a relation or on its direction. For example, in intertemporal choices humans discount larger delayed rewards less steeply than smaller ones, whereas in probabilistic choices such magnitude effect is either absent or reversed, with steeper discounting for smaller options. In addition, previous studies have shown that dispositional tendencies toward interpersonal dominance predict relevant behaviors in daily life, but no study to date explored their effect on the decision processes described above. Thus, in this study we aimed to investigate (i) the relationship between delay of gratification and risk propensity in human subjects, (ii) the effects on these behaviors of the subject's own social dominance profile, and (iii) the influence of the social dominance of an external observer on the subject’s choice behavior. We tested 177 Italian University students (73 males and 104 females) in Rome and Pisa with a questionnaire on intertemporal and probabilistic choices, and with a 21-items scale derived from the International Personality Item Pool (IPIP), successfully used in previous studies. There were three experimental conditions between-subjects: (i) No Observer: subjects responded to the questionnaire imagining to be alone in the test room; (ii) Dominant Observer: subjects responded while imagining to be observed by a socially dominant individual (by way of visual reinforcement, pictures of Barack Obama and Rita Levi Montalcini were included in the test instructions); (iii) Submissive Observer: subjects responded while imagining to be observed by a socially submissive individual (here visual reinforcement was provided by pictures of Ugo Fantozzi and Bridget Jones). We found a positive correlation between discount rates in intertemporal and probabilistic choices, whereas a significant magnitude effect was observed only for intertemporal choices. This result suggests that delayed and probabilistic outcomes do not involve the same underlying processes (otherwise the same manipulation of magnitude should have similar effects), although it leaves open the possibility that a common trait may be responsible for our individual propensity to either wait or take risks (hence the correlation between discount rates). Instead there was no significant effect of one's own interpersonal social dominance, as measured by the IPIP-scale, or of the presence of a dominant/submissive observer, as manipulated between-subjects, on either intertemporal or probabilistic choices. Preliminarily, this supports the view that both dispositional and contextual tendencies toward interpersonal dominance do not affect intertemporal and probabilistic choices. However, further research is needed to reach definitive conclusions on this point: among other things, it could be the case that just imagining the presence of a dominant/submissive individual is not enough to elicit the effect, whereas real presence would have an impact on choice behavior.