X. T. Wang

Sweet Future Fluctuating Blood Glucose Levels Affect Future Discounting

This study explored metabolic mechanisms of future (delay) discounting, a choice phenomenon where people value present goods over future goods. Using fluctuating blood glucose as an index of body-energy budget, optimal discounting should regulate choice among rewards as a function of temporal caloric requirement. We identified this novel link between blood glucose levels measured in the lab and future-discounting rates of participants, who made choices between a “smaller and sooner” reward and a “larger but later” option, with possible actual monetary rewards. A group of participants who drank a soft drink that contained sugar showed a reduced rate of future discounting afterward, when we controlled for sex, age, body mass index, and the taste of the drink. In contrast, a group of participants who drank a soft drink that contained artificial sweetener showed an increased rate of future discounting. Blood glucose levels not only varied as a result of caloric intake but also regulated the rate of future discounting, according to participants’ dynamic body-energy budget.

Social cues and verbal framing in risky choice

We examined how people use social and verbal cues of differing priorities in making social decisions. In Experiment 1, formally identical life – death choice problems were presented in different hypothetical group contexts and were phrased in either a positive or negative frame. The risk-seeking choice became more dominant as the number of kin in an endangered group increased. Framing effects occurred only in a heterogeneous group context where the lives at risk were a mixture of kin and strangers. No framing effect was found when the same problem was presented in the context of a homogeneous group consisting of either all kin or all strangers. We viewed the framing effects to be a sign of indecisive risk preference due to the differential effects of a kinship cue and a stranger cue on choice. In Experiment 2, we presented the life – death problem in two artificial group contexts involving either 6 billion human lives or 6 billion extraterrestrial lives. A framing effect was found only in the human context. Two pre-conditions of framing effects appear to be social unfamiliarity of a decision problem and aspiration level of a decision maker. In Experiment 3, we analyzed the direction of the framing effect by balancing the framing. The direction of the framing effect depended on the baseline level of risk preference determined by a specific decision context. Copyright

Risk as Reproductive Variance

In economics, normative utility theories of decision-making under risk use a single number (expected value) to index subjective utility at the cost of losing information about risk distribution. This paper examines how people make use of risk distributions (that is, variations in expected payoffs) to maximize the probability of reaching a goal and to minimize the likelihood of falling below a minimum requirement (MR). The author proposes and tests a Bounded Risk Distribution model using both hypothetical life–death problems and real reproductive and parental decision problems. Study 1 demonstrated that a given degree of increase in expected number of saved lives had a significant effect on the respondents’ risk preference when the increase was likely to cross the average MR of the respondents (in a small group context), but the same increase in expected value had little effect when the change was within a range below the average MR (in a kinship context) or above the MR (in a large group context). Study 2 examined alternative hypotheses for hypothetical risk acceptance with respect to kinship groups and found that whether the decision-maker was responsible or not had little effect on the setting of the MR and risk preference. The MR setting was mainly determined by the kinship context itself and was further fine-tuned by the framing of the choice outcomes. Study 3 was conducted in four rural villages in northwest China, and assessed real reproductive decisions. Interbirth intervals but not breast-feeding duration varied with a family’s wealth, the sex of a child, and the perceived resemblance of a child to a parent. These results are interpreted in terms of the same Bounded Risk Distribution model that was applied in the hypothetical scenario studies. D 2002 Elsevier Science Inc. All rights reserved.

Evolutionary hypotheses of risk-sensitive choice: Age differences and perspective change

Abstract This study tested specific predictions of risk preference in human choice derived from evolutionary hypotheses. The overall choice pattern revealed that subjects receiving a life-death decision problem described in a family context favored a risky probabilistic outcome over a statistically equivalent deterministic outcome. As predicted, the degree of such risk proneness varied as a function of sociobiologically important variables: the subjects age, their perspective, and the age cues about the hypothetical relatives saved in the deterministic outcome. Compared to young subjects, middle-aged subjects were much more prone to the deterministic outcome when it implied saving their younger family members but were extremely risk-seeking in favor of the probabilistic outcome when the deterministic choice resulted in the survival of older relatives. In contrast, the young subjects equally valued the younger and older hypothetical relatives and indistinguishably favored the probabilistic outcome under both saving-young and saving-old conditions. However, by changing the perspective of the young subjects from their own family to someone elses family, the saving-young deterministic outcome became more attractive than the saving-old deterministic outcome, resulting in differentiated risk-preference patterns. These results indicate an evolutionary origin of human reasoning and decision mechanisms that are sensitive to the biological characteristics of both decision makers and decision recipients.

Towards the development of an evolutionarily valid domain-specific risk-taking scale

From an evolutionary perspective, human risk-taking behaviors should be viewed in relation to evolutionarily recurrent survival and reproductive problems. In response to recent calls for domain-specific measures of risk-taking, we emphasize the need of evolutionarily valid domains. We report on two studies designed to validate a scale of risky behaviors in domains selected from research and theory in evolutionary psychology and biology, corresponding to reoccurring challenges in the ancestral environment. Behaviors were framed in situations which people would have some chance of encountering in modern times. We identify five domains of risk-taking: between-group competition, within-group competition, mating and resource allocation for mate attraction, environmental risks, and fertility risks.

A Tri-Reference Point Theory of Decision Making Under Risk

The tri-reference point (TRP) theory takes into account minimum requirements (MR), the status quo (SQ), and goals (G) in decision making under risk. The 3 reference points demarcate risky outcomes and risk perception into 4 functional regions: success (expected value of x ≥ G), gain (SQ < × < G), loss (MR ≤ x < SQ), and failure (x < MR). The psychological impact of achieving or failing to achieve these reference points is rank ordered as MR > G > SQ. We present TRP assumptions and value functions and a mathematical formalization of the theory. We conducted empirical tests of crucial TRP predictions using both explicit and implicit reference points. We show that decision makers consider both G and MR and give greater weight to MR than G, indicating failure aversion (i.e., the disutility of a failure is greater than the utility of a success in the same task) in addition to loss aversion (i.e., the disutility of a loss is greater than the utility of the same amount of gain). Captured by a double-S shaped value function with 3 inflection points, risk preferences switched between risk seeking and risk aversion when the distribution of a gamble straddled a different reference point. The existence of MR (not G) significantly shifted choice preference toward risk aversion even when the outcome distribution of a gamble was well above the MR. Single reference point based models such as prospect theory cannot consistently account for these findings. The TRP theory provides simple guidelines for evaluating risky choices for individuals and organizational management.

Emotions within reason: Resolving conflicts in risk preference

This research focused on differential effects of emotional and rational preferences in decision making and how people resolve conflicting risk preferences caused by inconsistency between their emotional reactions to and rational assessment of a risk problem. In addition, effects of the framing of choice outcomes on emotional, rational, and overall risk preferences were examined. Adopting a within-subjects design, Study 1 showed that the emotional choice preference was often the opposite of the rational choice preference and was more risk-seeking than the rational preference. The overall favourability rating for a chosen option was significantly higher when the emotional choice and rational choice were the same than when they were opposed. Emotional preferences were significantly more susceptible than rational preferences to the hedonic tone of risky choice framing. The overall preference was a compromise of the conflicting emotional and rational preferences in some risk domains, and resembled either the emotional preference or the rational preference in other risk domains. Study 2, using a between-subjects manipulation, further confirmed that emotional preference and rational preference had differential effects on risky choice.

Risk communication and risky choice in context: ambiguity and ambivalence hypothesis.

This chapter takes a synthetic approach to six related lines of research on decision making at risk and views risky choice as a function of cue use with priorities in the context of risk communication. An evolutionary analysis of risk and risk communication is presented in which risk is defined not only as variance in monetary payoff but also as variance in biological relatedness, social relations, and ultimately in reproductive fitness. Empirical evidence of ecological and social significance embedded in risk messages is analyzed, and how these risk cues affect behavioral decision making is examined. A new explanatory framework, the ambiguity and ambivalence hypothesis, identifies two key preconditions contributing to inconsistency and biases in making risky choices as a result of cue use in the course of risk communication.

Framing Effects: Behavioral Dynamics and Neural Basis

This study examined the neural basis of framing effects using life-death decision problems framed either positively in terms of lives saved or negatively in terms of lives lost in large group and small group contexts. Using functional MRI we found differential brain activations to the verbal and social cues embedded in the choice problems. In large group contexts, framing effects were significant where participants were more risk seeking under the negative (loss) framing than under the positive (gain) framing. This behavioral difference in risk preference was mainly regulated by the activation in the right inferior frontal gyrus, including the homologue of the Brocas area. In contrast, framing effects diminished in small group contexts while the insula and parietal lobe in the right hemisphere were distinctively activated, suggesting an important role of emotion in switching choice preference from an indecisive mode to a more consistent risk-taking inclination, governed by a kith-and-kin decision rationality.

Changes in Cognitive and Emotional Processing with Reproductive Status

Behavioral ratings on several affective scales (non-erotic/erotic, unpleasant/pleasant, simple/complex and low arousal/high arousal), and electrophysiological responses (event-related brain potentials) to emotional pictures, were collected from 30 female subjects, at different phases of their menstrual cycle. The pictures belonged to 5 emotional categories, whose content was babies, dermatological cases, ordinary people, male models and female models. The subjects were grouped into hormone defined phases, according to their expected levels of androgens, estrogen or progesterone. The data were analyzed to determine if emotional or cognitive processing was sensitive to the reproductive status, as indicated by menstrual phase. Only one component of event-related potentials, the P3 component, varied with menstrual phase. Baby and male model pictures elicited larger P3 waves when progesterone level was high. High progesterone was also associated with a decrease in complexity and eroticism to all picture categories. An increase in the pleasantness of all categories was evident when estrogen levels were high. The results are interpreted as support for a general proximal design, whereby emotional and cognitive processes are adaptively regulated by reproductive status.