Egocentric metric representations in peripersonal space: A bridge between motor resources and spatial memory

Research on visuospatial memory has shown that egocentric (subject-to-object) and allocentric (object-to-object) reference frames are connected to categorical (non-metric) and coordinate (metric) spatial relations, and that motor resources are recruited especially when processing spatial information in peripersonal (within arm reaching) than extrapersonal (outside arm reaching) space. In order to perform our daily-life activities, these spatial components cooperate along a continuum from recognition-related (e.g., recognizing stimuli) to action-related (e.g., reaching stimuli) purposes. Therefore, it is possible that some types of spatial representations rely more on action/motor processes than others. Here, we explored the role of motor resources in the combinations of these visuospatial memory components. A motor interference paradigm was adopted in which participants had their arms bent behind their back or free during a spatial memory task. This task consisted in memorizing triads of objects and then verbally judging what was the object: (1) closest to/farthest from the participant (egocentric coordinate); (2) to the right/left of the participant (egocentric categorical); (3) closest to/farthest from a target object (allocentric coordinate); and (4) on the right/left of a target object (allocentric categorical). The triads appeared in participants' peripersonal (Experiment 1) or extrapersonal (Experiment 2) space. The results of Experiment 1 showed that motor interference selectively damaged egocentric-coordinate judgements but not the other spatial combinations. The results of Experiment 2 showed that the interference effect disappeared when the objects were in the extrapersonal space. A third follow-up study using a within-subject design confirmed the overall pattern of results. Our findings provide evidence that motor resources play an important role in the combination of coordinate spatial relations and egocentric representations in peripersonal space.     

From segregation to intergroup contact and back: Using experiments and simulation to understand the bidirectional link

Research on intergroup contact has mostly viewed desegregation as a necessary condition for contact to unfold its power to reduce prejudice. Through residential and school choices, however, prejudice also contributes to segregation. To shed light on this bidirectional link, we conducted two survey‐based experiments with stratified quota samples of German adults. In Study 1, respondents with less contact and more prejudice indicated a lower likelihood of renting an apartment in a neighborhood with a larger proportion of minority members, although housing quality and crime rate were held constant. In Study 2, similar results were obtained for the likelihood of enrolling their child at a school with a larger proportion of minority students. Building on these results in a computer simulation, we find that because contact only reduces prejudice, but does not produce pro‐minority preferences, spontaneous desegregation is unlikely to occur even under the most favorable structural and economic conditions.     

Computing the real solutions of Fleishman's equations for simulating non-normal data

Fleishman's power method is frequently used to simulate non-normal data with a desired skewness and kurtosis. Fleishman's method requires solving a system of nonlinear equations to find the third-order polynomial weights that transform a standard normal variable into a non-normal variable with desired moments. Most users of the power method seem unaware that Fleishman's equations have multiple solutions for typical combinations of skewness and kurtosis. Furthermore, researchers lack a simple method for exploring the multiple solutions of Fleishman's equations, so most applications only consider a single solution. In this paper, we propose novel methods for finding all real-valued solutions of Fleishman's equations. Additionally, we characterize the solutions in terms of differences in higher order moments. Our theoretical analysis of the power method reveals that there typically exists two solutions of Fleishman's equations that have noteworthy differences in higher order moments. Using simulated examples, we demonstrate that these differences can have remarkable effects on the shape of the non-normal distribution, as well as the sampling distributions of statistics calculated from the data. Some considerations for choosing a solution are discussed, and some recommendations for improved reporting standards are provided.     

The Predictive Role of Simulations in Assessing Military Performance

The current study assessed the predictive validity of simulations to improve the military selection system. Four navy simulations were developed and their predictive validity was measured. The performance of 1007 Israeli navy soldiers was measured in a longitudinal study, which was carried on for almost two years. Participants’ performance in four simulations (naval-navigation test, raft sailing, rubber boat [zodiac] mounting, and military tent assembly) was measured and used as a behavioral predictor for their performance at the end of their first year of active military service on combat ships. All but the raft sailing simulation predicted participants’ performance.     

Generating Recommendations for Simulator Design Through Pilot Assessment of Prototype Utility

Incorporated in a simulator design project, this study assessed the utility of a simulator prototype for air combat training to optimize continued development. After several scenarios, the 13 male participants completed a survey. Seven fidelity levels: visual feedback, head-up/head-down, instrumentation, flight controls, graphics, visual resolution, and field-of-view were rated for three dimensions: realism, limitation of performance, and importance of realism. The results informed decisions about which fidelity levels, head-up/head-down and field-of-view, that should be prioritized during the next design cycle, and generated recommendations for continued simulator design and directives for further evaluations.     

Elastic solutions with arbitrary elastic inhomogeneity and anisotropy

An efficient numerical algorithm is proposed to accurately compute the elastic fields in two-dimensional (2D) or three-dimensional (3D) microstructures with arbitrary elastic inhomogeneity and anisotropy. It combines the equivalent inclusion method of Eshelby, the microelasticity theory of Khachaturyan, and the spectral iterative perturbation method of Hu and Chen. Its efficiency is compared with those of existing approaches in the literature. The method can be conveniently implemented in phase-field modeling of stress-dependent microstructure evolution and/or of mass/electrical transport.