Perception-Movement Coupling in the Regulation of Step Lengths When Approaching an Obstacle

Experiment 1 showed that the control mechanism based on a perception–movement coupling observed in certain goal-directed movement tasks (De Rugy, Montagne, Buekers, & Laurent, 2000 De Rugy, A., Montagne, G., Buekers, M. J. and Laurent, M. 2000. The study of locomotor pointing in virtual reality: The validation of a test set-up. Behavior Research Methods, Instruments, & Computers, 32: 515–520.  [Google Scholar]; Montagne, Cornus, Glize, Quaine, & Laurent, 2000 Montagne, G., Cornus, S., Glize, D., Quaine, F. and Laurent, M. 2000. A perception-action coupling type of control in long-jumping. Journal of Motor Behavior, 32: 37–44. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) can be extended to a stepping across an obstacle task. Regardless of the specificity of tasks, the initiation of regulations is a function of the amount of adjustment. Our participants organized their regulation later than long jumpers. Two additional experiments were conceived to investigate whether this control mechanism could be generalized to goal-directed locomotor displacements, with different constraints. The aim of Experiments 2 and 3 was to address the adaptation of this control mechanism by manipulating the obstacle width and the walking speed in a stepping across task. The results showed that the functioning of this control mechanism could be influenced by the spatiotemporal constraints. Participants' behavior depended on a perception–movement coupling. This study suggests the existence of a generic control mechanism based on a perception–movement coupling, and it emphasizes the adaptation of this type of control mechanism involved in goal-directed displacements.     

Assessment of Identity and Quality of Life in Diabetic and Renal Transplant Adolescents in Comparison to Healthy Adolescents

Identity development represents a central task of adolescence. Identity achievement is characterized by a coherent sense of who one is following a period of exploration and can help navigate the challenges of adulthood. This study examined identity within a quality of life (QOL) context in 85 adolescents with a renal transplant or with Type 1 diabetes in comparison to 90 healthy controls. Results revealed significant differences in ideological identity, with patients showing higher levels of diffusion and controls showing higher levels of foreclosure. No differences with respect to interpersonal identity, QOL, perceived control over the QOL domains, and perceived opportunities for growth and development were found. Future research should assess identity and QOL over a longer period of time to determine whether differences between chronically ill and healthy young adults can be detected.     

Quantifying the contribution of low-level saliency to human eye movements in dynamic scenes

We investigated the contribution of low-level saliency to human eye movements in complex dynamic scenes. Eye movements were recorded while naive observers viewed a heterogeneous collection of 50 video clips (46,489 frames; 4-6 subjects per clip), yielding 11,916 saccades of amplitude ≥2°. A model of bottom-up visual attention computed instantaneous saliency at the instant each saccade started and at its future endpoint location. Median model-predicted saliency was 45% the maximum saliency, a significant factor 2.03 greater than expected by chance. Motion and temporal change were stronger predictors of human saccades than colour, intensity, or orientation features, with the best predictor being the sum of all features. There was no significant correlation between model-predicted saliency and duration of fixation. A majority of saccades were directed to a minority of locations reliably marked as salient by the model, suggesting that bottom-up saliency may provide a set of candidate saccade target locations, with the final choice of which location of fixate more strongly determined top-down.     

Expertise in basketball modifies perceptual discrimination abilities,underlying cognitive processes,and visual behaviours

In this paper, the links between cognitive constraints, visual behaviours, and perceptual judgements are examined. Two experiments investigated the perceptual processes employed during same-different judgement tasks. In Experiment 1, experts' eye movements (i.e., number of fixations and fixation duration) were consistent across discrepant source and target conditions where the number of displaced elements was manipulated. In contrast, novices decreased the number of fixations employed as the number of elements displaced increased. The findings are consistent with the view that both experts and novices process information in a manner (relational or attributional) that constrains the type of visual search used (low or high sensitive to attributional change). In Experiment 2, manipulation of target presentation confirmed that recognition was viewpoint dependent for both expert and novice players. The degradation in performance was accompanied by a change in the visual search behaviours employed by experts, which confirmed thr strength of the search–cognition–performance links     

On Being Exposed to Superior Others: Consequences of Self-Threatening Upward Social Comparisons

Being inferior to someone else can be hurtful. But what exactly happens when we found ourselves in such situations? We first address why and when upward comparison can be self-threatening and later review the effects of such threatening social comparison. We argue that two main kinds of disturbances can ensue: affective disturbances and attentional disturbances. Second, three ways to deal with self-threatening social comparison are reviewed: proactive regulation, defensive regulation, and regulation by avoidance. For each of these disturbances and regulation modes, we review empirical findings and later discuss the impact of upward comparison on performance. We conclude by going back to the very need behind the need for a positive evaluation.     

Is the principle of minimization of secondary moments validated during various fingertip force production conditions?

During the application of fingertip forces with simultaneous flexion of the four fingers, namely index, middle, ring, and little fingers, a stable force sharing among fingers is adopted. Several studies have hypothesized that this stable force sharing is established to minimize unnecessary rotational moments (different from the main flexion moments). This principle labeled "minimization of secondary moments" is presented in the literature as a principle used by the central nervous system to solve musculoskeletal redundancy. However, this principle has only been tested with one solicited degree of freedom and in one finger posture. Our study tests this principle with various degrees of freedom solicited as secondary moments and in two different finger postures. Participants (n=6) were asked to apply a downward vertical force using their four fingers with the forearm placed in two different configurations: a "horizontal" condition (involving flexion/extension and pronation/supination at the wrist joint) and a "vertical" condition (involving flexion/extension and radial/ulnar deviation at the wrist joint). Additionally, two finger postures were tested in each forearm configuration: in the first, the distal inter-phalangeal joints (DIP) were extended and the proximal inter-phalangeal joints (PIP) highly flexed. In the second finger posture, both DIP and PIP joints were flexed. The resultant four-finger force and the relative involvement of each finger in the resultant four-finger force (force sharing) were analyzed. Results showed that the finger postures did not influence the finger force sharing, showing that the minimization of the secondary moment principle was stable among the finger joint angle configurations. Nonetheless, the relative involvement of each finger was dependent on the secondary degree of freedom solicited (pronation/supination vs. radial/ulnar). The modifications of the finger force sharing between the "horizontal" and "vertical" conditions were in accordance with the principle of minimization of the secondary moments.     

Measuring Positive Affect,Negative Affect,and Physiological Hyperarousal among Italian Youth: Translations of the PANAS-C and PH-C

Italian-language versions of the Positive and Negative Affect Scale for Children (PANAS-C; Laurent et al. Psychological Assessment, 11, 326–338, 1999) and Physiological Hyperarousal Scale for Children (PH-C; Laurent et al. Psychological Assessment, 16, 373–380, 2004) were developed. Students (N = 1026; M age = 12.05 years, SD = 1.49) from central Italy completed these scales. Measures were evaluated based on criteria from previous studies resulting in an 11-item PANAS-C PA scale (α = .88), a 13-item PANAS-C NA scale (α = .87), and a 14-item PH-C (α = .85). Confirmatory factor analyses resulted in best-fit indices that favored a 3-factor model consistent with the tripartite model of anxiety and depression. Similar to results reported with the original English-language and other translations of these measures, scores on the PA scale were lower and scores on the NA and PH scales were higher for older girls than older boys and younger boys and girls. Findings suggested that the psychometric properties of the Italian-language versions of the PANAS-C and PH-C were similar to the English-language versions and other translated versions of the measures.     

A simple technique to study embodied language processes: the grip force sensor

Research in cognitive neuroscience has shown that brain structures serving perceptual, emotional, and motor processes are also recruited during the understanding of language when it refers to emotion, perception, and action. However, the exact linguistic and extralinguistic conditions under which such language-induced activity in modality-specific cortex is triggered are not yet well understood. The purpose of this study is to introduce a simple experimental technique that allows for the online measure of language-induced activity in motor structures of the brain. This technique consists in the use of a grip force sensor that captures subtle grip force variations while participants listen to words and sentences. Since grip force reflects activity in motor brain structures, the continuous monitoring of force fluctuations provides a fine-grained estimation of motor activity across time. In other terms, this method allows for both localization of the source of language-induced activity to motor brain structures and high temporal resolution of the recorded data. To facilitate comparison of the data to be collected with this tool, we present two experiments that describe in detail the technical setup, the nature of the recorded data, and the analyses (including justification about the data filtering and artifact rejection) that we applied. We also discuss how the tool could be used in other domains of behavioral research.