Not All Bad Apples Spoil the Bunch: Order Effects on the Evaluation of Groups

When group members are encountered in a random sequential order, people expect the first (vs. middle or last) member to be more diagnostic of the group. Therefore, they weigh the performance of the first (vs. middle or last) more heavily in their predictions and decisions about the whole group

Non--Newtonian gravity and coherence properties of light

In this work the possibility of detecting a non--Newtonian contribution to the gravitational potential by means of its effects upon the first and second--order coherence properties of light is analyzed. It will be proved that, in principle, the effects of a fifth force upon the correlation functions of electromagnetic radiation could be used to detect the existence of new forces. Some constraints upon the experimental parameters will also be deduced.Comment: 10 pages, accepted in Physics Letters

Approximate trajectory data for missions to the major planets

Contour charts and tables on trajectory data for missions to Jupiter, Saturn, Uranus, and Neptune and their moon

The First-Member Heuristic: Group Members Labeled “First” Influence Judgment and Treatment of Groups

People often make judgments about a group (e.g., immigrants from a specific country) based on information about a single group member. Seven studies (N = 1,929) tested the hypothesis that people will expect the performance of an arbitrarily ordered group to match that of the group member in the first position of a sequence more closely than that of group members in other positions. This greater perceived diagnosticity of the first member will in turn affect how people treat the group. This pattern of judgment and treatment of groups, labeled the “firstmember heuristic,” generalized across various performance contexts (e.g., gymnastic outine, relay race, job performance), and regardless of whether the focal member performed poorly or well (Studies 1-3). Consistent with the notion that first members are deemed most informative, participants were most likely to turn to the member in the first (vs. other) position to learn about the group (Study 4). Further, through their disproportionate influence on the expected performance of other group members, first members’ performances also influenced participants’ support of policies that would benefit or hurt a group (Study 5) and their likelihood to join a group (Study 6). Finally, perceived group homogeneity moderated the first-member heuristic, such that it attenuated for nonhomogeneous groups (Study 7)

Integrating theories of self-control and motivation to advance endurance performance

Self-control is a burgeoning research topic within sport and motivational psychology. Following efforts to define and contextualize self-control, characteristics of self-control are considered that have important implications for sport performance. We describe and evaluate various theoretical perspectives on self-control, including limited resources, shifting priorities, and opportunity-costs. The research described includes sport-specific research but also studies that focus on general motivational principles that look beyond sport-specific phenomena. We propose that attentional, rather than limited resource, explanations of self-control have more value for athletic performance. Moreover, we integrate self-control ideas with descriptions of motivational phenomena to derive novel hypotheses concerning how self-control can be optimized during sport performance. We explain how minimizing desire-goal conflicts by fusing self-control processes and performance goals can delay aversive consequences of self-control that may impede performance. We also suggest that autonomous performance goals are an important motivational input that enhances the effectiveness of self-control processes by a) reducing the salience of the desire to reduce performance-related discomfort, b) increasing attentional resources towards optimal performance, and c) optimizing monitoring and modification of self-control processes. These extensions to knowledge help map out empirical agenda which may drive theoretical advances and deepen understanding of how to improve self-control during performance

Phantom energy mediates a long-range repulsive force

Scalar field models with non-standard kinetic terms have been proposed in the context of k-inflation, of Born-Infeld lagrangians, of phantom energy and, more in general, of low-energy string theory. In general, scalar fields are expected to couple to matter inducing a new interaction. In this paper I derive the cosmological perturbation equations and the Yukawa correction to gravity for such general models. I find three interesting results: first, when the field behaves as phantom energy (equation of state less than -1) then the coupling strength is negative, inducing a long-range repulsive force; second, the dark energy field might cluster on astrophysical scales; third, applying the formalism to a Brans-Dicke theory with general kinetic term it is shown that its Newtonian effects depend on a single parameter that generalizes the Brans-Dicke constant.Comment: 5 pages; accepted on Phys. Rev. Lett. v2: two references adde

Lorentz Invariance and the Cosmological Constant

Non-trivial solutions in string field theory may lead to the spontaneous breaking of Lorentz invariance and to new tensor-matter interactions. It is argued that requiring the contribution of the vacuum expectation values of Lorentz tensors to account for the vacuum energy up to the level that $\Omega_{0}^{\Lambda} = 0.5$ implies the new interactions range is $\lambda \sim 10^{-4} m$. These conjectured violations of the Lorentz symmetry are consistent with the most stringent experimental limits.Comment: 13 pages, plain Latex. This essay was selected for an honorable mention in the 1997 Gravity Research Foundation essay competio

Ultracold neutrons, quantum effects of gravity and the Weak Equivalence Principle

We consider an extension of the recent experiment with ultracold neutrons and the quantization of its vertical motion in order to test the Weak Equivalence Principle. We show that an improvement on the energy resolution of the experiment may allow to establish a modest limit to the Weak Equivalence Principle and on the gravitational screening constant. We also discuss the influence of a possible new interaction of Nature.Comment: Revtex4, 4 pages. Discussion on the equivalence principle altered. Bound is improve