Computer Games and Prosocial Behaviour

We relate different self-reported measures of computer use to individuals' propensity to cooperate in the Prisoner's dilemma. The average cooperation rate is positively related to the self-reported amount participants spend playing computer games. None of the other computer time use variables (including time spent on social media, browsing internet, working etc.) are significantly related to cooperation rates

Risk and Temptation: A Meta-Study on Social Dilemma Games

This paper reports the results of a meta-study of 89 prisoner's dilemma experiments comprising more than 3000 participants across 6 countries. We organize existing evidence and explain seemingly contradictory results in the existing literature by focusing on two dimensions of the dilemma: "risk'' (the percentage loss of unilaterally cooperating against a defector) and "temptation'' (the percentage gain of unilaterally defecting against a cooperator). We find in particular, that (i) risk best explains the variation in cooperation rates across random matching ("stranger'') and one-shot treatments, while (ii) temptation best explains the variation in repeated ("partner'') interactions, (iii) consistently with reputational models temptation is more effectively contained the longer the time horizon of the game, (iv) there is more cooperation in partner than stranger if and only if risk is high and temptation low and (v) women are more cooperative than the average man if risk is low and less cooperative if risk is high, but there are no gender differences on average. These results can be useful for discriminating between competing theories of why people cooperate. For policy making, it is important to understand which dimension of the dilemma (risk or temptation) is best targeted via interventions to yield improved cooperation

Extrapolation in games of coordination and dominance solvable games

We study extrapolation between games in a laboratory experiment. Participants in our experiment first play either the dominance solvable guessing game or a Coordination version of the guessing game for five rounds. Afterwards they play a 3x3 normal form game for ten rounds with random matching which is either a game solvable through iterated elimination of dominated strategies (IEDS), a pure Coordination game or a Coordination game with pareto ranked equilibria. We find strong evidence that participants do extrapolate between games. Playing a strategically different game hurts compared to the control treatment where no guessing game is played before and in fact impedes convergence to Nash equilibrium in both the 3x3 IEDS and the Coordination games. Playing a strategically similar game before leads to faster convergence to Nash equilibrium in the second game. In the Coordination games some participants try to use the first game as a Coordination device. Our design and results allow us to conclude that participants do not only learn about the population and/or succesful actions, but that they are also able to learn structural properties of the games

Near-Infrared-Spectroscopy with Extremely Large Telescopes: Integral-Field- versus Multi-Object-Instruments

Integral-field-spectroscopy and multi-object-spectroscopy provide the high multiplex gain required for efficient use of the upcoming generation of extremely large telescopes. We present instrument developments and designs for both concepts, and how these designs can be applied to cryogenic near-infrared instrumentation. Specifically, the fiber-based concept stands out the possibility to expand it to any number of image points, and its modularity predestines it to become the new concept for multi-field-spectroscopy. Which of the three concepts --- integral-field-, multi-object-, or multi-field-spectroscopy --- is best suited for the largest telescopes is discussed considering the size of the objects and their density on the sky.Comment: 8 pages, 4 figures (converted to bitmap), to appear in the proceedings of the Workshop on Extremely Large Telescopes, Sweden, June 1-2, 1999, uses spie.sty (V0.91) and spiebib.bst (V0.91

A new era of spectroscopy: SINFONI, NIR integral field spectroscopy at the diffraction limit of an 8m telescope

SINFONI, the SINgle Faint Object Near-infrared Investigation, is an instrument for the Very Large Telescope (VLT), which will start its operation mid 2002 and allow for the first time near infrared (NIR) integral field spectroscopy at the diffraction limit of an 8-m telescope. SINFONI is the combination of two state-of-the art instruments, the integral field spectrometer SPIFFI, built by the Max-Planck-Institut fuer extraterrestrische Physik (MPE), and the adaptive optics (AO) system MACAO, built by the European Southern Observatory (ESO). It will allow a unique type of observations by delivering simultaneously high spatial resolution (pixel sizes 0.025arcsec to 0.25arcsec) and a moderate spectral resolution (R~2000 to R~4500), where the higher spectral resolution mode will allow for software OH suppression. This opens new prospects for astronomy.Comment: 9 pages, 4 figures, to appear in SPIE proceedings "Astronomical Telescopes and Instrumentation 2000". More recent sensitivity estimates are available at http://www.mpe.mpg.de/www_ir/ir_instruments/sinfoni/spiffi.ht

Decision Making with Imperfect Knowledge of the State Space

We conduct an experiment to study how imperfect knowledge of the state space affects subsequent choices under uncertainty with perfect knowledge of the state space. Participants in our experiment choose between a sure outcome and a lottery in 32 periods. All treatments are exactly identical in periods 17 to 32 but differ in periods 1 to 16. In the early periods of the ?Risk Treatment? there is perfect information about the lottery; in the ?Ambiguity Treatment? participants perfectly know the outcome space but not the associated probabilities; in the ?Unawareness Treatment? participants have imperfect knowledge about both outcomes and probabilities. All three treatments induce strong behavioural differences in periods 17 to 32. In particular participants who have been exposed to an environment with very imperfect knowledge of the state space subsequently choose lotteries with high (low) variance less (more) often compared to other participants. Estimating individual risk attitudes from choices in periods 17 to 32 we find that the distribution of risk attitude parameters across our treatments can be ranked in terms of first order stochastic dominance. Our results show how exposure to different degrees of uncertainty can have long-lasting effects on individuals? risk-taking behaviour

Behavioural Variation in Tullock contests

We conduct an experiment to uncover the reasons behind the typically large behavioral variation and low explanatory power of Nash equilibrium observed in Tullock contests. In our standard contest treatment, only 7% of choices are consistent with Nash equilibrium which is in line with the literature and roughly what random (uniform) choice would predict (6.25%). We consider a large class of social, risk and some other non-standard preferences and show that heterogeneity in preferences cannot explain these results. We then systematically vary the complexity of both components of Nash behaviour: (I) the difficulty to form correct beliefs and (II) the difficulty to formulate best responses. In treatments where both the difficulty of forming correct beliefs and of formulating best responses is reduced behavioural variation decreases substantially and the explanatory behaviour of Nash equilibrium increases dramatically (explaining 65% of choices with a further 20% being close to NE). Our results show that bounded rationality rather than heterogeneity in preferences is the reason behind the huge behavioral variation typically observed in Tullock contests

Past experience of uncertainty affects risk aversion

In an experiment with more than 500 participants we study how past experience of uncertainty (imperfect knowledge of the state space) affects risk preferences. Participants in our experiment choose between a sure outcome and a lottery in 32 periods. All treatments are exactly identical in periods 17–32 but differ in periods 1–16. In the early periods of the risk treatment there is perfect information about the lottery; in the ambiguity Treatment participants perfectly know the outcome space but not the associated probabilities; in the unawareness treatment participants have imperfect knowledge about both outcomes and probabilities. We observe strong treatment effects on behavior in periods 17–32. In particular, participants who have been exposed to an environment with very imperfect knowledge of the state space subsequently choose lotteries with high (low) variance less (more) often compared to other participants. Estimating individual risk attitudes from choices in periods 17–32 we find that the distribution of risk attitude parameters across our treatments can be ranked in terms of first order stochastic dominance. Our results show how exposure to environments with different degrees of uncertainty can affect individuals’ subsequent risk-taking behavior