5,456 research outputs found
How choice reveals and shapes expected hedonic outcome
Humans tend to modify their attitudes to align with past action. For example, after choosing between similarly valued alternatives, people rate the selected option as better than they originally did, and the rejected option as worse. However, it is unknown whether these modifications in evaluation reflect an underlying change in the physiological representation of a stimulus' expected hedonic value and our emotional response to it. Here, we addressed this question by combining participants' estimations of the pleasure they will derive from future events, with brain imaging data recorded while they imagined those events, both before, and after, choosing between them. Participants rated the selected alternatives as better after the decision stage relative to before, whereas discarded alternatives were valued less. Our functional magnetic resonance imaging findings reveal that postchoice changes in preference are tracked in caudate nucleus activity. Specifically, the difference in blood oxygenation level-dependent (BOLD) signal associated with the selected and rejected stimuli was enhanced after a decision was taken, reflecting the choice that had just been made. This finding suggests that the physiological representation of a stimulus' expected hedonic value is altered by a commitment to it. Furthermore, before any revaluation induced by the decision process, our data show that BOLD signal in this same region reflects the choices we are likely to make at a later time
The neurobiology of reference-dependent value computation
A key focus of current research in neuroeconomics concerns how the human brain computes value. Although, value has generally been viewed as an absolute measure (e.g., expected value, reward magnitude), much evidence suggests that value is more often computed with respect to a changing reference point, rather than in isolation. Here, we present the results of a study aimed to dissociate brain regions involved in reference-independent (i.e., “absolute”) value computations, from those involved in value computations relative to a reference point. During functional magnetic resonance imaging, subjects acted as buyers and sellers during a market exchange of lottery tickets. At a behavioral level, we demonstrate that subjects systematically accorded a higher value to objects they owned relative to those they did not, an effect that results from a shift in reference point (i.e., status quo bias or endowment effect). Our results show that activity
in orbitofrontal cortex and dorsal striatum track parameters such as the expected value of lottery tickets indicating the computation of reference-independent value. In contrast, activity in ventral striatum indexed the degree to which stated prices, at a within-subjects and between-subjects level, were distorted with respect to a reference point. The findings speak to the neurobiological underpinnings of reference dependency during real market value computations
Explaining enhanced logical consistency during decision making in autism
The emotional responses elicited by the way options are framed often results in lack of logical consistency in human decision making. In this study, we investigated subjects with autism spectrum disorder (ASD) using a financial task in which the monetary prospects were presented as either loss or gain. We report both behavioral evidence that ASD subjects show a reduced susceptibility to the framing effect and psycho-physiological evidence that they fail to incorporate emotional context into the decision-making process. On this basis, we suggest that this insensitivity to contextual frame, although enhancing choice consistency in ASD, may also underpin core deficits in this disorder. These data highlight both benefits and costs arising from multiple decision processes in human cognition
An action variable of the sine-Gordon model
It was conjectured that the classical bosonic string in AdS times a sphere
has a special action variable which corresponds to the length of the operator
on the field theory side. We discuss the analogous action variable in the
sine-Gordon model. We explain the relation between this action variable and the
Backlund transformations and show that the corresponding hidden symmetry acts
on breathers by shifting their phase. It can be considered a nonlinear analogue
of splitting the solution of the free field equations into the positive- and
negative-frequency part.Comment: v3,4: added explanations, discussion of O(N) sigma-model in section 5
v5: correction in the Introduction, small change
A projective Dirac operator on CP^2 within fuzzy geometry
We propose an ansatz for the commutative canonical spin_c Dirac operator on
CP^2 in a global geometric approach using the right invariant (left action-)
induced vector fields from SU(3). This ansatz is suitable for noncommutative
generalisation within the framework of fuzzy geometry. Along the way we
identify the physical spinors and construct the canonical spin_c bundle in this
formulation. The chirality operator is also given in two equivalent forms.
Finally, using representation theory we obtain the eigenspinors and calculate
the full spectrum. We use an argument from the fuzzy complex projective space
CP^2_F based on the fuzzy analogue of the unprojected spin_c bundle to show
that our commutative projected spin_c bundle has the correct
SU(3)-representation content.Comment: reduced to 27 pages, minor corrections, minor improvements, typos
correcte
Equivalence between Kaluza Klein modes of gravitinos and goldstinos in brane induced supersymmetry breaking
We identify the goldstino fields that give mass to the Kaluza Klein modes of
five dimensional supergravity, when supersymmetry breaking is induced by brane
effects. We then proof the four dimensional Equivalence Theorem that, in
renormalizable gauges, allows for the replacement of Kaluza Klein modes of
helicity gravitinos in terms of goldstinos. Finally we identify the
five dimensional renormalizable gauge fixing that leads to the Equivalence
Theorem.Comment: Final version published in JHEP. Typo corrected in eq. 2.
Electron paramagnetic resonance study of .pi. system interaction in dithiin derivatives
The anion radical of tetracyanodithiin (I) is shown to be a divalent sulfur system in which d-orbital participation
in conjugation is negligible. The g value (2.0024) indicates that spin-orbit coupling is very
small, and a molecular =ode1 shows that direct A-A overlap of the ethylene moieties is probable. Other
S-containing cation and anion systems are compared, including 2,5-diphenyldithiin (IV) and tetracyanothiophene
(VI). Large cation g value deviations and small anion deviations of S heterocycles are contrasted
with hydrocarbon
Addendum to “Absorption of a massive scalar field by a charged black hole”
In [1] we studied the absorption cross section of a scalar field of mass m impinging on a static black hole of mass M and charge Q. We presented numerical results using the partial-wave method, and analytical results in the high- and low-frequency limit. Our low-frequency approximation was only valid if the (dimensionless) field velocity v exceeds vc=2πMm. In this addendum we give the complementary result for v≲vc, and we consider the possible physical relevance of this regime
An invariant approach to dynamical fuzzy spaces with a three-index variable
A dynamical fuzzy space might be described by a three-index variable
C_{ab}^c, which determines the algebraic relations f_a f_b =C_{ab}^c f_c among
the functions f_a on the fuzzy space. A fuzzy analogue of the general
coordinate transformation would be given by the general linear transformation
on f_a. I study equations for the three-index variable invariant under the
general linear transformation, and show that the solutions can be generally
constructed from the invariant tensors of Lie groups. As specific examples, I
study SO(3) symmetric solutions, and discuss the construction of a scalar field
theory on a fuzzy two-sphere within this framework.Comment: Typos corrected, 12 pages, 8 figures, LaTeX, JHEP clas
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