The robustness of the "Raise-The-Stakes" strategy - Coping with exploitation in noisy Prisoner's Dilemma Games.

Recent models of altruism point out the success of a strategy called 'Raise-The- Stakes' (RTS) in situations allowing variability in cooperation. In theory, RTS is difficult to exploit because it begins with a small investment in an iterated Prisoner's Dilemma Game. When its cooperation is reciprocated, RTS increases its generosity, thereby taking advantage of cooperative opportunities. Previous research has shown that human subjects indeed adopt RTS but start out moderately cooperative rather than with a minimal investment. This raises the question how robust RTS is against exploitation, certainly in a noisy situation. In a behavioral experiment we investigate whether human subjects vary their cooperation in interaction with reciprocators and cheaters in an iterated non-discrete version of a Prisoner's Dilemma Game. When confronted with a strategy that matches the investment of the subject on the previous round, we find that subjects are likely to increase cooperation. However, cooperation gradually breaks down in interaction with a strategy that undercuts the level of cooperation of the subjects, indicating the robustness of RTS. In line with RTS modeling studies, but in contrast with the cheater detection literature, we find that human subjects are less willing to increase cooperation when the perceived likelihood of mistakes increases.Cheating; Evolution of cooperation; Noise; Prisoner's dilemma; Reciprocal altruism;

Digit ratio (2D:4D) moderates the impact of sexual cues on men's decisions in ultimatum games9079.

Three experimental studies demonstrate that 'sex-related cues' impact human decision making in ultimatum games. In the ultimatum game, two individuals divide a sum of money. The proposer offers a portion of the money to the other player, the responder. If the responder accepts the offer, the money is distributed in agreement with the proposer's offer. If the responder rejects the offer, neither player receives anything. Our studies show that exposure to pictures of sexy women or lingerie increases the likelihood of accepting unfair offers. Digit ratios of responders are reliably associated with responder's behaviour: Males with lower digit ratios are more likely to reject an unfair split in neutral contexts, but more likely to accept unfair offers in sex related contexts.Behavior; Cognition; Consumer behavior; Cost; Decision; Decision making; Decisions; Exposure; Impact; Likelihood; Performance; Processes; Ratios; Research; Science; Self-control; Studies; Theory; University;

Making better partner matches in brand alliances

With many brand alliances failing to add value, understanding the factors that make for a strong pairing becomes essential. Appropriately, harnessing techniques similar to those used by dating sites to determine whether people will make a good match has helped reveal the answers

Bikinis instigate generalized impatience in intertemporal choice.

Neuroscientific studies demonstrate that erotic stimuli activate the reward circuitry processing monetary and drug rewards. Theoretically, a general reward system may give rise to non-specific effects: Exposure to 'hot stimuli' from one domain may thus affect decisions in a different domain. We show that exposure to sexy cues leads to more impatience in intertemporal choice between monetary rewards. Highlighting the role of a general reward circuitry, we demonstrate that individuals with a sensitive reward system are more susceptible to the effect of sex cues, that the effect generalizes to non-monetary rewards, and that satiation attenuates the effect.Choice; Decision; Decisions; Effects; Exposures; Studies;

Are prosocials unique in their egalitarianism? The pursuit of equality in outcomes among individualists.

The present research aims to elucidate to what extent the motive to ensure equality in outcomes is general and to what extent it interacts with other important motives such as maximizing own or collective gains. Because individuals may have different considerations and motivations in decision-making situations, it is likely that people with a different social value orientation will respond differently to an unequal distribution of outcomes. Contrary to our expectations, not only prosocials care about equality in outcomes. In study 1, we found that individualists choose to forego personal gains, despite obvious selfish reasons to cooperate, when outcomes were distributed unequally. In a second experiment we replicate this finding and show that individualists, just as do prosocials, demand equality in outcomes in interdependent situations. Our studies suggest that typifying individualists as solely being concerned about enhancing personal outcomes is too limited.Cooperation; Decision making; Demand; Distribution; Equality; Personal; Research; Social Value Orientation; Social values; Studies; Tit-For-Tat; Value;

Bending arms, bending discounting functions. How motor actions affect intertemporal decision-making.

In five studies we demonstrate that task-irrelevant somatic activity influences intertemporal decision making: Arm movements associated with approach (arm flexion), rather than avoidance (arm extension), instigate present-biased preferences. We show that the preference for immediate over delayed gratification is moderated by the sensitivity of the approach system and, owing to learning principles, restricted to arm positions of the dominant hand. This research extends the effects of somatic activity beyond attitude formation and cognition, and provides empirical evidence for the effect of somatic activity on motivational systems.