Too Clever by Half

Kevin Lewis

January 02, 2010

Bearded capuchin monkeys' and a human's efficiency at cracking palm nuts with stone tools: Field experiments

D. Fragaszy, T. Pickering, Q. Liu, P. Izar, E. Ottoni & E. Visalberghi
Animal Behaviour, forthcoming

Wild bearded capuchins, Cebus libidinosus, in Fazenda Boa Vista, Brazil crack tough palm nuts using hammer stones. We analysed the contribution of intrinsic factors (body weight, behaviour), size of the nuts and the anvil surface (flat or pit) to the efficiency of cracking. We provided capuchins with local palm nuts and a single hammer stone at an anvil. From video we scored the capuchins' position and actions with the nut prior to each strike, and outcomes of each strike. The most efficient capuchin opened 15 nuts per 100 strikes (6.6 strikes per nut). The least efficient capuchin that succeeded in opening a nut opened 1.32 nuts per 100 strikes (more than 75 strikes per nut). Body weight and diameter of the nut best predicted whether a capuchin would crack a nut on a given strike. All the capuchins consistently placed nuts into pits. To provide an independent analysis of the effect of placing the nut into a pit, we filmed an adult human cracking nuts on the same anvil using the same stone. The human displaced the nut on proportionally fewer strikes when he placed it into a pit rather than on a flat surface. Thus the capuchins placed the nut in a more effective location on the anvil to crack it. Nut cracking as practised by bearded capuchins is a striking example of a plastic behaviour where costs and benefits vary enormously across individuals, and where efficiency requires years to attain.


The Value of Superstitions

Travis Ng, Terence Chong & Xin Du
Journal of Economic Psychology, forthcoming

This paper estimates the value of superstitions by studying the auctions of vehicle license plates. We show that the value of superstitions is economically significant, which justifies their persistence in human civilization. We also document the changes of the value of superstitions across different types of plates, across different policy regimes, and across different macroeconomic environments. Interestingly, some of the changes are rather consistent with economic intuition.


What Happens in the Field Stays in the Field: Exploring Whether Professionals Play Minimax in Laboratory Experiments

Steven Levitt, John List & David Reiley
NBER Working Paper, December 2009

The minimax argument represents game theory in its most elegant form: simple but with stark predictions. Although some of these predictions have been met with reasonable success in the field, experimental data have generally not provided results close to the theoretical predictions. In a striking study, Palacios-Huerta and Volij (2007) present evidence that potentially resolves this puzzle: both amateur and professional soccer players play nearly exact minimax strategies in laboratory experiments. In this paper, we establish important bounds on these results by examining the behavior of four distinct subject pools: college students, bridge professionals, world-class poker players, who have vast experience with high-stakes randomization in card games, and American professional soccer players. In contrast to Palacios-Huerta and Volij's results, we find little evidence that real-world experience transfers to the lab in these games-indeed, similar to previous experimental results, all four subject pools provide choices that are generally not close to minimax predictions. We use two additional pieces of evidence to explore why professionals do not perform well in the lab: (1) complementary experimental treatments that pit professionals against preprogrammed computers, and (2) post-experiment questionnaires. The most likely explanation is that these professionals are unable to transfer their skills at randomization from the familiar context of the field to the unfamiliar context of the lab.


Prefer a cash slap in your face over credit for halva

Hamed Ekhtiari, Arian Behzadi, Morteza Dehghani, Ali Jannati & Azarakhsh Mokri
Judgment and Decision Making, December 2009, Pages 534-542

We investigated how frequency and amount of punishment affect the decision making of Iranian subjects. In our first experiment, performing a computer-based Persian version of the Iowa Gambling Task (IGT), our subjects scored remarkably lower than their Western counterparts. Moreover, our subjects chose more frequently and more rapidly from decks that had less frequent but larger amounts of punishments in comparison to decks that had more frequent punishments with smaller amounts. In our second experiment, subjects did not differentiate between decks with the same frequency of punishment but with different punishment amounts. However, among decks with the same amount but different frequency of punishment, a significant preference was apparent towards decks with less frequency of punishment. Our results differ from previous studies, indicating a different strategy in risky decision making among healthy adult Iranian subjects, as they show low attention to the amount of punishment and are more concerned with the frequency of punishment.


Are irrational reactions to unfairness truly emotionally-driven? Dissociated behavioural and emotional responses in the Ultimatum Game task

Claudia Civai, Corrado Corradi-Dell'Acqua, Matthias Gamer & Raffaella Rumiati
Cognition, January 2010, Pages 89-95

The "irrational" rejections of unfair offers by people playing the Ultimatum Game (UG), a widely used laboratory model of economical decision-making, have traditionally been associated with negative emotions, such as frustration, elicited by unfairness ([Sanfey et al., 2003] and [van't Wout et al., 2006]). We recorded skin conductance responses as a measure of emotional activation while participants performed a modified version of the UG, in which they were asked to play both for themselves and on behalf of a third-party. Our findings show that even unfair offers are rejected when participants' payoff is not affected (third-party condition); however, they show an increase in the emotional activation specifically when they are rejecting offers directed towards themselves (myself condition). These results suggest that theories emphasizing negative emotions as the critical factor of "irrational" rejections (Pillutla & Murninghan, 1996) should be re-discussed. Psychological mechanisms other than emotions might be better candidates for explaining this behaviour.


The Signaling Power of Sanctions in Social Dilemmas

Joël van der Weele
Journal of Law, Economics, and Organization, forthcoming

Evidence from field and laboratory experiments indicates that a large fraction of the people behave like conditional cooperators in public good games. In this article, I investigate the implications of the existence of both conditional cooperators and egoists for optimal law enforcement strategies. When norms of cooperation exist between conditional cooperators, sanctions set by an authority can be lower than in a "Hobbesian" setting where everybody is egoistic. Moreover, if the authorities have private information about the fraction of egoists in society, low sanctions can be optimal because they signal that there are few defectors and thus "crowd in" trust and cooperation between agents. In social dilemmas where conditional cooperation is an important factor, as is the case in tax compliance, the model provides a rationale for the low observed sanctions in the real world and the mixed evidence on the effectiveness of deterrence.


Monopoly® Pricing

John Cawley & Donald Kenkel
Economic Inquiry, forthcoming

There is a large and rich literature in economics on monopoly pricing. However, a close examination of this literature reveals a surprising gap: there have been virtually no studies of Monopoly® pricing. We fill that void with an empirical examination of the pricing of the board game Monopoly®. In particular, we examine market-level, quarterly prices from 1990 to 2002 and find substantial evidence of the phenomenon of customary pricing.

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