Minimal Social Cues in the Dictator Game

This paper reports results of an incentivized laboratory experiment manipulating an extremely weak social cue in the Dictator Game. Prior to making their decision, we present dictators with a simple visual stimlulus: either three dots in a “watching-eyes” configuration, or three dots in a neutral configuration. The watching-eyes configuration is suggestive of a schematic face—a stimuli that is known to weakly activate the fusiform face area of the brain (Tong, et al., 2000; Bednar and Miikkulainen, 2003; Johnson and Morton, 1991). Given the experimental evidence for automatic priming of watching eyes of others, it is thus reasonable to hypothesize that even though the social cue is very weak, this activation might be sufficient to produce a significant change in social behavior. Our results demonstrate that such a weak social cue does increase giving behavior—even under conditions of complete anonymity—and this difference in behavior across subjects is entirely explained by differences in the choice behavior of males. In fact, males in our treatment condition, who typically act more selfishly than do females in conditions of complete anonymity, give twice as much to anonymous recipients than females give.dictator game, social preferences, laboratory experiment, social distance

Nucleon-Nucleon Potential and its Non-locality in Lattice QCD

By the quenched lattice QCD simulation for two nucleons with finite scattering energy, validity of the delivative expansion of the general nucleon-nucleon potential U(r,r') = V(r, {\nabla}_r) \delta^3(r-r') is studied. The relative kinetic energy between two nucleons is introduced through the anti-periodic boundary condition in the spatial directions. On a hypercubic lattice with the lattice spacing a ~ 0.137 fm and the spatial extent L_s ~ 4.4 fm with the pion mass m_{\pi} ~ 530 MeV, the local potentials for two different energies (E ~ 0 MeV and 45 MeV) are compared and found to be identical within statistical errors, which validates the local approximation of U(r,r') up to E=45 MeV for the central and tensor potentials. Central potentials in the spin-singlet channel for different orbital angular momentums (l=0 and l=2) at E ~ 45 MeV are also found to be the same within the errors, which also supports the local approximation.Comment: 15 pages, 16 figure

Energy dependence of nucleon-nucleon potentials

We investigate the energy dependence of potentials defined through the Bethe-Salpeter wave functions. We analytically evaluate such a potential in the Ising field theory in 2 dimensions and show that its energy dependence is weak at low energy. We then numerically calculate the nucleon-nucleon potential at non-zero energy using quenched QCD with anti-periodic boundary condition. In this case we also observe that the potentials are almost identical at $E\simeq 0$ and $E\simeq 50$ MeV, where $E$ is the center of mass kinetic energy.Comment: 7 pages, 5 figures, talk presented at the XXVI International Symposium on Lattice Field Theory, July 14-19, 2008, Williamsburg, Virginia, US

Baryon-Baryon Interactions in the Flavor SU(3) Limit from Full QCD Simulations on the Lattice

We investigate baryon-baryon (BB) interactions in the 3-flavor full QCD simulations with degenerate quark masses for all flavors. The BB potentials in the orbital S-wave are extracted from the Nambu-Bethe-Salpeter wave functions measured on the lattice. We observe strong flavor-spin dependences of the BB potentials at short distances. In particular, a strong repulsive core exists in the flavor-octet and spin-singlet channel (the 8_s representation), while an attractive core appears in the flavor singlet channel (the 1 representation). We discuss a relation of such flavor-spin dependence with the Pauli exclusion principle in the quark level. Possible existence of an H-dibaryon resonance above the Lambda-Lambda threshold is also discussed.Comment: 16 pages, 4 figures, ptptex.cls use