Alteration of the perceived path of a non-pursued target during smooth pursuit: Analysis by a neural network model

AbstractDuring pursuit of a circularly moving target, the perceived movement of a second circularly moving target is altered. The perceived movement of the non-pursued target is different from both its real movement path and its retinal path. In the present paper this phenomenon is studied using a physiologically based neural network model. Simulation results were compared to psychophysical findings in human subjects. Model simulations enabled us to suggest an explanation for this phenomenon in terms of underlying physiological mechanisms and to estimate the contribution of the efferent eye-movement signal to the perceptual process

Similarity Effect and Optimal Control of Multiple-Choice Decision Making

SummaryDecision making with several choice options is central to cognition. To elucidate the neural mechanisms of such decisions, we investigated a recurrent cortical circuit model in which fluctuating spiking neural dynamics underlie trial-by-trial stochastic decisions. The model encodes a continuous analog stimulus feature and is thus applicable to multiple-choice decisions. Importantly, the continuous network captures similarity between alternatives and possible overlaps in their neural representation. Model simulations accounted for behavioral as well as single-unit neurophysiological data from a recent monkey experiment and revealed testable predictions about the patterns of error rate as a function of the similarity between the correct and actual choices. We also found that the similarity and number of options affect speed and accuracy of responses. A mechanism is proposed for flexible control of speed-accuracy tradeoff, based on a simple top-down signal to the decision circuit that may vary nonmonotonically with the number of choice alternatives

A social relations analysis of young children's trust in their peers across the early years of school

Two hundred and five (103 female and 102 male) children enrolled in school years 1 and 2 in the United Kingdom (mean age 6 years 1 month at Time 1) were tested twice over a 1-year period. The children reported the promise keeping and secret keeping behaviours of classmates (all peers and same-gender peers) and provided friendship nominations (Time 2 only). Round robin social relations analyses for all peers and same-gender peers revealed: (a) perceiver variance, demonstrating consistent individual differences in trust beliefs in peers; (b) target variance, demonstrating consistent individual differences in eliciting trust from peers; and, (c) dyadic reciprocity, demonstrating reciprocal trust between individuals. Replicability across measures, stability, and cross-measure stability of these effects were found for all peers only. As hypothesised, the perceiver and target effects of trust were associated with the number of friendships. The findings support the concl usion that young children demonstrate multiple components of trust in dyadic relationships, which are associated with their social relationships

The early childhood generalized trust belief scale

The study was designed to develop and evaluate the Early Childhood Generalized Trust Belief Scale (ECGTBS) as a method of assessing 5-to-8-year-olds’ generalized trust. Two hundred and eleven (103 male and 108 female) children (mean age 6 years and 2 months at Time 1) completed the ECGTBS twice over a year. A subsample of participants completed the ECGTBS after two weeks to assess the scale’s test-retest reliability. Exploratory and confirmatory factor analyses confirmed that the ECGTBS assessed the expected three factors: reliability, emotional trust, and honesty with item-pairs loading most strongly on their corresponding factor. However, the ECGTBS demonstrated low to modest internal consistency and test-retest reliability which indicates a need for further development of this instrument. As evidence for the convergent validity of the ECGTBS, the reliability and emotional trust items were associated with the children’s trust in classmates at Time 2. Concurrent asymmetric quadratic relationships indicated the importance of midrange generalized trust. Specifically, children with very high generalized trust experienced greater loneliness and children with very low generalized trust had fewer friendships than children with midrange trust

Young children's interpersonal trust consistency as a predictor of future school adjustment

Young children’s interpersonal trust consistency was examined as a predictor of future school adjustment. One hundred and ninety two (95 male and 97 female, M age = 6 years 2 months, SD age = 6 months) children from school years 1 and 2 in the United Kingdom were tested twice over one-year. Children completed measures of peer trust and school adjustment and teachers completed the Short-Form Teacher Rating Scale of School Adjustment. Longitudinal quadratic relationships emerged between consistency of children’s peer trust beliefs and peer-reported trustworthiness and school adjustment and these varied according to social group, facet of trust, and indictor of school adjustment. The findings support the conclusion that interpersonal trust consistency, especially for secret-keeping, predicts aspects of young children’s school adjustment

Theta dependence of SU(N) gauge theories in the presence of a topological term

We review results concerning the theta dependence of 4D SU(N) gauge theories and QCD, where theta is the coefficient of the CP-violating topological term in the Lagrangian. In particular, we discuss theta dependence in the large-N limit. Most results have been obtained within the lattice formulation of the theory via numerical simulations, which allow to investigate the theta dependence of the ground-state energy and the spectrum around theta=0 by determining the moments of the topological charge distribution, and their correlations with other observables. We discuss the various methods which have been employed to determine the topological susceptibility, and higher-order terms of the theta expansion. We review results at zero and finite temperature. We show that the results support the scenario obtained by general large-N scaling arguments, and in particular the Witten-Veneziano mechanism to explain the U(1)_A problem. We also compare with results obtained by other approaches, especially in the large-N limit, where the issue has been also addressed using, for example, the AdS/CFT correspondence. We discuss issues related to theta dependence in full QCD: the neutron electric dipole moment, the dependence of the topological susceptibility on the quark masses, the U(1)_A symmetry breaking at finite temperature. We also consider the 2D CP(N) model, which is an interesting theoretical laboratory to study issues related to topology. We review analytical results in the large-N limit, and numerical results within its lattice formulation. Finally, we discuss the main features of the two-point correlation function of the topological charge density.Comment: A typo in Eq. (3.9) has been corrected. An additional subsection (5.2) has been inserted to demonstrate the nonrenormalizability of the relevant theta parameter in the presence of massive fermions, which implies that the continuum (a -> 0) limit must be taken keeping theta fixe