424 research outputs found
Evaluating three frameworks for the value of information: adaptation to task characteristics and probabilistic structure
We identify, and provide an integration of, three frameworks for measuring the
informativeness of cues in a multiple-cue judgment task. Cues can be ranked by information
value according to expected information gain (Bayesian framework), cue-outcome correlation
(Correlational framework), or ecological validity (Ecological framework). In three
experiments, all frameworks significantly predicted information acquisition, with the
Correlational (then the Bayesian) framework being most successful. Additionally,
participants adapted successfully to task characteristics (cue cost, time pressure, and
information limitations) â altering the gross amount of information acquired, but not
responding to more subtle features of the cuesâ information value that would have been
beneficial. Rational analyses of our task environments indicate that participants' behavior can
be considered successful from a boundedly rational standpoint
Go for broke: The role of somatic states when asked to lose in the Iowa Gambling Task
© 2016 The Author(s) The Somatic Marker Hypothesis (SMH) posits that somatic states develop and guide advantageous decision making by âmarkingâ disadvantageous options (i.e., arousal increases when poor options are considered). This assumption was tested using the standard Iowa Gambling Task (IGT) in which participants win/lose money by selecting among four decks of cards, and an alternative version, identical in both structure and payoffs, but with the aim changed to lose as much money as possible. This âloseâ version of the IGT reverses which decks are advantageous/disadvantageous; and so reverses which decks should be marked by somatic responses â which we assessed via skin conductance (SC). Participants learned to pick advantageously in the original (Win) IGT and in the (new) Lose IGT. Using multilevel regression, some variability in anticipatory SC across blocks was found but no consistent effect of anticipatory SC on disadvantageous deck selections. Thus, while we successfully developed a new way to test the central claims of the SMH, we did not find consistent support for the SMH
The need to belong and the value of belongings: Does ostracism change the subjective value of personal possessions?
A growing body of research has demonstrated that feelings of possession influence the valuation of personal possessions. Psychological theories of ownership suggest that a special bond between a person and his/her possession arises in response to the innate motivation for effectance, self-identity and need for home. However, current empirical support is insufficient to make a causal link between these psychological needs and feelings of ownership. In four studies (total N > 800), we manipulated peopleâs basic needs by inducing feelings of ostracism, which threatens the needs for belonging, self-esteem, control, and belief in a meaningful existence. Despite the fact that these social needs are closely related to the putative antecedents of feelings of ownership, the ostracism manipulation did not significantly affect participantsâ feelings of ownership, or their valuations of their possessions, whether measured by willingness to accept or willingness to pay. These results suggest that the special bond that people have with their belongings is not readily used to restore basic psychological needs following the experience of social exclusion.This is the author accepted manuscript. The final version is available at http://www.sciencedirect.com/science/article/pii/S2214804315000725
Non-perturbative renormalisation for overlap fermions
Using non-perturbative techniques we have found the renormalisation factor,
Z, in the RI-MOM scheme for quark bilinear operators in quenched QCD. We worked
with overlap fermions using the Luescher-Weisz gauge action. Our calculation
was performed at beta=8.45 at a lattice spacing of 1/a=2.1 GeV using a value of
rho=1.4. Our results show good agreement between the vector and the axial
vector in the zero mass limit. This shows that overlap fermions have good
chiral properties. To attempt to improve the discretisation errors in our
results we subtracted the O(a^2) terms in one-loop lattice perturbation theory
from the Monte Carlo Green functions. In particular we paid attention to the
operators for the observable . We found a value for the renormalisation
constants Z^msbar_(v_2b) and Z^msbar_(v_2a) just less than 1.9 at mu=1/a=2.1
GeV.Comment: 6 pages, 3 figures, uses PoS style, poster presented at Lattice 2005
(Chiral Fermions), to be published in Proceedings of Scienc
The electric dipole moment of the nucleon from simulations at imaginary vacuum angle theta
We compute the electric dipole moment of proton and neutron from lattice QCD
simulations with N_f=2 flavors of dynamical quarks at imaginary vacuum angle
theta. The calculation proceeds via the CP odd form factor F_3. A novel feature
of our calculation is that we use partially twisted boundary conditions to
extract F_3 at zero momentum transfer. As a byproduct, we test the QCD vacuum
at nonvanishing theta.Comment: 22 pages, 10 figure
Perturbative Wilson loops from unquenched Monte Carlo simulations at weak couplings
Perturbative expansions of several small Wilson loops are computed through
next-to-next-to-leading order in unquenched lattice QCD, from Monte Carlo
simulations at weak couplings. This approach provides a much simpler
alternative to conventional diagrammatic perturbation theory, and is applied
here for the first time to full QCD. Two different sets of lattice actions are
considered: one set uses the unimproved plaquette gluon action together with
the unimproved staggered-quark action; the other set uses the one-loop-improved
Symanzik gauge-field action together with the so-called ``asqtad''
improved-staggered quark action. Simulations are also done with different
numbers of dynamical fermions. An extensive study of the systematic
uncertainties is presented, which demonstrates that the small third-order
perturbative component of the observables can be reliably extracted from
simulation data. We also investigate the use of the rational hybrid Monte Carlo
algorithm for unquenched simulations with unimproved-staggered fermions. Our
results are in excellent agreement with diagrammatic perturbation theory, and
provide an important cross-check of the perturbation theory input to a recent
determination of the strong coupling by the HPQCD
collaboration.Comment: 14 pages, 8 figure
Deep inelastic scattering and factorization in the 't Hooft Model
We study in detail deep inelastic scattering in the 't Hooft model. We are
able to analytically check current conservation and to obtain analytic
expressions for the matrix elements with relative precision O(1/Q^2) for 1-x >>
\beta^2/Q^2. This allows us to compute the electron-meson differential cross
section and its moments with 1/Q^2 precision. For the former we find maximal
violations of quark-hadron duality, as it is expected for a large N_c analysis.
For the latter we find violations of the operator product expansion at
next-to-leading order in the 1/Q^2 expansion.Comment: 55 pages, 16 figure
A lattice determination of g_A and <x> from overlap fermions
We present results for the nucleon's axial charge g_A and the first moment
of the unpolarized parton distribution function from a simulation of
quenched overlap fermions.Comment: Talk presented at Lattice2004(chiral), 4 pages, 4 figure
Random Matrix Theory, Chiral Perturbation Theory, and Lattice Data
Recently, the chiral logarithms predicted by quenched chiral perturbation
theory have been extracted from lattice calculations of hadron masses. We argue
that the deviations of lattice results from random matrix theory starting
around the so-called Thouless energy can be understood in terms of chiral
perturbation theory as well. Comparison of lattice data with chiral
perturbation theory formulae allows us to compute the pion decay constant. We
present results from a calculation for quenched SU(2) with Kogut-Susskind
fermions at \beta=2.0 and 2.2.Comment: LaTeX, 12 pages, 7 .eps figure
Random Matrix Theory and Chiral Logarithms
Recently, the contributions of chiral logarithms predicted by quenched chiral
perturbation theory have been extracted from lattice calculations of hadron
masses. We argue that a detailed comparison of random matrix theory and lattice
calculations allows for a precise determination of such corrections. We
estimate the relative size of the m*log(m), m, and m^2 corrections to the
chiral condensate for quenched SU(2).Comment: LaTeX (elsart.cls), 9 pages, 6 .eps figures, added reference, altered
discussion of Eq.(9
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