Visual motion disambiguation by a subliminal sound

There is growing interest in the effect of sound on visual motion perception. One model involves the illusion created when two identical objects moving towards each other on a two-dimensional visual display can be seen to either bounce off or stream through each other. Previous studies show that the large bias normally seen toward the streaming percept can be modulated by the presentation of an auditory event at the moment of coincidence. However, no reports to date provide sufficient evidence to indicate whether the sound bounce-inducing effect is due to a perceptual binding process or merely to an explicit inference resulting from the transient auditory stimulus resembling a physical collision of two objects. In the present study, we used a novel experimental design in which a subliminal sound was presented either 150 ms before, at, or 150 ms after the moment of coincidence of two disks moving towards each other. The results showed that there was an increased perception of bouncing (rather than streaming) when the subliminal sound was presented at or 150 ms after the moment of coincidence compared to when no sound was presented. These findings provide the first empirical demonstration that activation of the human auditory system without reaching consciousness affects the perception of an ambiguous visual motion display.     

Coordination of complex bimanual multijoint movements under increasing cycling frequencies: The prevalence of mirror-image and translational symmetry

The present study examined the principles underlying inter and intralimb coordination constraints during performance of bimanual elbow–wrist movements at different cycling frequencies (from 0.75 Hz to 2.50 Hz). Participants performed eight coordination tasks that consisted of a combination of in-phase (IN) and/or anti-phase (AN) coordination modes between both elbows and wrists (interlimb), with isodirectional (Iso) or non-isodirectional (NonI) coordination modes within each limb (intralimb). As expected, the principle of muscle homology (in-phase coordination), giving rise to mirror symmetrical movements with respect to the mid-sagittal plane, had a powerful influence on the quality of global coordinative behavior both between and within limbs. When this principle was violated (i.e., when the anti-phase mode was introduced in one or both joint pairs), the non-isodirectional intralimb mode exhibited a (de)stabilizing role in coordination, which became more pronounced at higher cycling frequencies. However, pattern loss with increasing cycling frequency resulted not only in convergence toward the more stable in-phase patterns with the elbows and wrists but also to the anti-phase patterns (which were associated with directional compatibility of within-limb motions). Moreover, participants generally preserved their initial mode of coordination (either in-phase or anti-phase) in the proximal joints (i.e., elbows) while shifting from anti-phase to in-phase (or vice versa) with their distal joint pair (i.e., wrists). Taken together, these findings reflect the impact of two immanent types of symmetry in bimanual coordination: mirror-image and translational symmetry.     

Imaging Brain Effects of APOE4 in Cognitively Normal Individuals Across the Lifespan

The ε4 allele of the apolipoprotein E (APOE4) is associated with an increased risk of developing Alzheimer’s disease (AD). Hence, several studies have compared the brain characteristics of APOE4 carriers versus non-carriers in presymptomatic stages to determine early AD biomarkers. The present review provides an overview on APOE4-related brain changes in cognitively normal individuals, focusing on the main neuroimaging biomarkers for AD, i.e. cortical beta-amyloid (Aβ) deposition, hypometabolism and atrophy. The most consistent findings are observed with Aβ deposition as most studies report significantly higher cortical Aβ load in APOE4 carriers compared with non-carriers. Fluorodeoxyglucose-positron emission tomography studies are rare and tend to show hypometabolism in brain regions typically impaired in AD. Structural magnetic resonance imaging findings are the most numerous and also the most discrepant, showing atrophy in AD-sensitive regions in some studies but contradicting results as well. Altogether, this suggests a graded effect of APOE4, with a predominant effect on Aβ over brain structure and metabolism. Multimodal studies confirm this view and also suggest that APOE4 effects on brain structure and function are mediated by both Aβ-dependent and Aβ-independent pathological processes. Neuroimaging studies on asymptomatic APOE4 carriers offer relevant information to the understanding of early pathological mechanisms of the disease, although caution is needed as to whether APOE4 effects reflect AD pathological processes, and are representative of these effects in non-carriers.     

Bouncing between model and data: stability, passivity, and optimality in hybrid dynamics

Rhythmically bouncing a ball with a racket is a seemingly simple task, but it poses all the challenges critical for coordinative behavior: perceiving the ball's trajectory to adapt position and velocity of the racket for the next ball contact. To gain insight into the underlying control strategies, the authors conducted a series of studies that tested models with experimental data, with an emphasis on deriving model-based hypotheses and trying to falsify them. Starting with a simple dynamical model of the racket and ball interactions, stability analyses showed that open-loop dynamics affords dynamical stability, such that small perturbations do not require corrections. To obtain this passive stability, the ball has to be impacted with negative acceleration--a strategy that subjects adopted in a variety of conditions at steady state. However, experimental tests that applied perturbations revealed that after perturbations, subjects applied active perceptually guided corrections to reestablish steady state faster than by relying on the passive model's relaxation alone. Hence, the authors derived a model with active control based on optimality principles that considered each impact as a separate reaching-like movement. This model captured some additional features of the racket trajectory but failed to predict more fine-grained aspects of performance. The authors proceed to present a new model that accounts not only for fine-grained behavior but also reconciles passive and active control approaches with new predictions that will be put to test in the next set of experiments.     

Frequency,characteristics and functions of future‐oriented thoughts in daily life

Despite the growing interest in future‐oriented cognition in various areas of psychology, there is still little empirical data regarding the occurrence and nature of future‐oriented thoughts in daily life. In this study, participants recorded future‐oriented thoughts occurring in natural settings and rated their characteristics and functions. The results show that future‐oriented thoughts occur frequently in daily life and can take different representational formats (more or less abstract), embrace various thematic contents (e.g. work, relationships) and serve a range of functions (e.g. action planning, decision making). The functions and characteristics of thoughts differed according to their temporal distance, with thoughts referring to the near future being more specific and serving action planning to a greater extent than thoughts concerning the far future. The characteristics of future thoughts were also related to affective content, with positive thoughts being more frequent, more specific, and associated with more visual images than negative thoughts. Copyright © 2009 John Wiley & Sons, Ltd.     

Completed suicides among Quebec adolescents involved with juvenile justice and child welfare services

In the Province of Quebec (Canada), adolescents involved with the child welfare and juvenile justice systems committed at least one third of all completed suicides in their age group in 1995 and 1996. Their risk of suicide, standardized for age and sex, was five times that of the general adolescent population, and female juvenile delinquents had the highest relative risk of suicide (36.1). Cumulated risk factors may explain those results. Since 40% of those suicides did occur when subjects were still actively involved with the child welfare and juvenile justice systems, those agencies should revise their suicide prevention strategies.     

The "ticktock" of our internal clock: direct brain evidence of subjective accents in isochronous sequences

The phenomenon commonly known as subjective accenting refers to the fact that identical sound events within purely isochronous sequences are perceived as unequal. Although subjective accenting has been extensively explored using behavioral methods, no physiological evidence has ever been provided for it. In the present study, we tested the notion that these perceived irregularities are related to the dynamic deployment of attention. We disrupted listeners' expectancies in different positions of auditory equitone sequences and measured their responses through brain event-related potentials (ERPs). Significant differences in a late parietal (P3-like) ERP component were found between the responses elicited on odd-numbered versus even-numbered positions, suggesting that a default binary metric structure was perceived. Our findings indicate that this phenomenon has a rather cognitive, attention-dependent origin, partly affected by musical expertise.     

Causalité juridique et imputabilité médicale : l’incidence de l’approche juridique du lien de causalité sur la pratique expertale en droit de la réparation du dommage corporel

Traditionally, a “direct and certain” causal link was required between fault and harm in order to engage an individual's compensatory liability. However, upon reading case law, it is possible to note that causality no longer necessarily has to be either direct or certain. Indeed, although the presence of a previous condition long enabled the exclusion of a direct link between a harmful event and its aftereffects, the French Court of Appeal (Cour de Cassation) now considers that pathological predispositions must no longer be taken into account (in respect of an exclusion or a reduction in the right to compensation) if these were latent, and only revealed by the harmful event. Similarly, on occasion the plaintiffs support their claims with bundles of evidence and arguments that can but force magistrates to set aside the absence of absolute certainty on a scientific level. Presumptions of accountability have even been put forward in some areas of personal injury compensation (traffic accidents and workplace accidents). The conduct and content of forensic expertises are then disrupted, both for the expert and for the victim's lawyer.     

Presence as determined by fractal perceptual-motor dynamics.

This paper presents a tentative model of the role of perceptual-motor dynamics in the emergence of the feeling of presence. A new method allowing the measure of how gaze probes three-dimensional space in immersion is used to support this model. Fractal computations of gaze behavior are shown to be more effective than standard computations of eye movements in predicting presence.     

Jobs Commensurate With Their Skills? Selected Workers and Skilled Job Access in Québec

The ability of recent landed immigrants to find employment that is commensurate with their skills is a frequent subject of debate. This article analyses one dimension of this phenomenon: namely, how well does post-landing employment correlate to pre-landing levels of education as measured through the Québec selection grid. The analysis is done through a longitudinal retrospective survey of a probabilistic sample of principal applicants from the economic class admitted to Québec between January 1997 and June 2000. In order to better measure the condition of immigrants at their time of arrival, the results of the survey are analysed along with the administrative data taken from Québec’s selection grid and the confirmation of permanent residence. This article analyses the speed of the requalification that the members of the economic class undertake. This analysis attempts to answer two questions: Is the level attained by the cohort normal? At what speed do these immigrants attain these expected outcomes?