A Note on Motor Learning Without Post-Response Knowledge of Results

The authors studied the adjustment of the 2 distinct known expressions of gait velocity, the velocity of the center of gravity (CG) and the velocity of the center of foot pressure (CP) at the end of the 1st step in 2 experimental situations: natural gait initiation (the control situation, CS) and heel-off gait initiation (the test situation, TS). Gait was initiated by 7 healthy participants, from an erect spontaneous posture in the CS and from a posture with heels raised in the TS, on a force platform at 3 self-selected speed conditions. Biomechanical data from the force platform were collected in both experimental situations, and the authors used a particular gait analysis based on the differential method of Y. Brenière (2003) in order to approach velocity modulation by means of step length and frequency. Results showed that CG and CP velocities were adjusted differently during heel-off gait initiation than during natural gait initiation. CP velocity, as compared with CG velocity, was overestimated in TS. Results also established the relevance of the expression of step velocity by means of step length and frequency: The central nervous system, taking into account the specific postural constraints of each experimental situation, uses a reference value and a regulating parameter to modulate step velocity. Moreover, the contributions of 1st step length and frequency to the expression of step velocity in TS and CS were different. Thus, a specific locomotor behavior corresponds to a given experimental situation that is characterized by its own initial biomechanical constraints.     

Clinical application of attachment theory in permanency planning for children in foster care: The importance of continuity of care

Permanency planning is a critical issue facing all children in foster care. Foster children frequently suffer from developmental delays and severe behavior problems, often leading to repeated displacements that in turn increase the risk for attachment disorders. To prevent the emergence of such disturbances, an Attachment Clinic was developed in Montreal to offer consultation to Youth Protection workers. A specific problem has frequently been identified in this Clinic: Should a child who has developed a significant attachment to his or her foster parents return to the biological parents or stay in the foster family? The choice between the two families is even more difficult when the parenting competencies of the biological parents seem to have progressed while the child has developed secure attachments in the foster family. Clinical cases will be presented to illustrate such dilemmas. Concepts rooted in attachment theory have been very useful to understand such problems, and have led us to believe that children's best interests lie in the preservation of their attachment ties and that repeated ruptures of such ties constitute a severe trauma. Resistances of the milieu to our position will be discussed as well as the Court's decisions in light of Canadian jurisprudence.     

Attachment,self-esteem,and psychomotor development in extremely premature children at preschool age

The aim of the study was to evaluate concomitantly self-esteem and model of attachment to the mother in extremely premature (24–28 weeks of gestation) and full-term children, in relation to the child's variables (neonatal condition, gender, cognitive development) and family variables (family adversity, socioeconomic status). Forty-two extremely premature and 27 fullterm children were assessed at 5 years 9 months. For the premature children, neonatal status and developmental quotient (DQ) at 18 months were also obtained. Premature and fullterm children did not differ in attachment and self-esteem categories. For all subjects, IQ at 5 years 9 months differed significantly across self-esteem categories. Seventy percent of premature children who showed a decrease in IQ from 18 months to 5 years 9 months had a negative self-esteem. In the premature group, DQ at 18 months was lower for the children that were categorized at 5 years 9 months with nonsecure attachment to the mother. Attachment appeared sensitive to early neuromotor impairments, and self-esteem to the developmental level at the time of the evaluation.     

Whose Rights Count? Negotiating Practice,Policy, and Legal Dilemmas Regarding Infant–Parent Contact When Infants are in Out‐of‐Home Care

This article takes a human rights perspective with a view to articulating the infant's perspective when the infant has been subjected to abuse, neglect, or both and is reliant on the state to ensure his or her health and well‐being. When a young child is removed from parental care, important and often difficult decisions have to be made about subsequent contact between child and parent. We consider a number of dilemmas which may arise for practitioners when they are assisting child welfare decision makers in relation to contact, and acknowledge the limited empirical follow‐up studies of the impact of child welfare practice and legal decisions on infant outcomes. We draw on the significant and substantive evidence base about infant emotional and cognitive development and infant–parent attachment relationships as well as infant mental health to illuminate the infant's subjective experience in these practice dilemmas. We describe innovations in practice from various countries, which seek to shed light on the challenges often associated with contact.     

Differential Method of Characterizing Gait Strategies From Step Lengths and Frequencies: Strategy of Velocity Modulation

The differential method consists of the analysis of the variation of gait parameters length, frequency, and velocity with respect to their mean values, respectively, ΔL = L — L_m , Δf = f — f_m , and Δv = v – v_m , where L_m , f_m , and v_m represent the mean values of those parameters. Assuming that the strategy of modulation of velocity implies that L and f are functions of v and that statistical analyses of ratios ΔL/Δv and Δf/Δv have established that there is a very significant linear correlation, close to 1, between those ratios, the mathematical procedure allows one to determine the equation of step length, L = a · f + b · v + K, where a and b are the slope and the intercept of the linear regression and K is close to L_m . The equation was experimentally tested on 140 gait sequences performed by 6 participants and for gait velocities ranging from 0.6 to 2.2 m/s and was found to be very representative of all individual values. The differential method provides another way of using the derivative of velocity, v = L·f, to characterize the strategy of velocity modulation, which then permits one to determine the linear equation of velocity, v = f · L_m + L · f_m — L_m · f_m , and to show that the respective parts played by each parameter in the progression velocity are approximately equal. The author establishes the uniqueness of the different linear adjustments and discusses the differential method's own modes of use, that is, interindividually or globally.     

The mind of society: Investigating and using the “language of the gods”

The “language of the gods” is conceived as a kind of language more complex than what we associate with human tongues in the strict sense of the term. Certain arbitrary regularities throughout the rational disciplines appear to indicate the existence of this language. The present article explores this new concept and applies it in an attempt to provide a logical clarification of the notions of individual consciousness and physical reality.     

Analysis of the transition from upright stance to steady state locomotion in children with under 200 days of autonomous walking

The aim of this paper was to study, from a developmental perspective, the transient phase of gait during the period between the standing posture and the achievement of steady state gait, using temporal and biochemical parameters. Eight children who had been walking autonomously for 90 to 200 days were observed. A total of 64 sequences of steps were analyzed. A sequence of steps began with the child standing still and was executed on a large force plate. From the determination of the instantaneous velocity of center of gravity results establish that, unlike adults, progression velocity in children end of the first step, but after two to four steps.The gait initiation process does not depend on the steady state velocity, but results from an initial fall. The duration of the movement up to the end of the first step is independent of the progression velocity but depends only upon the body mass and moment of inertia of the children.     

Dynamical implication of anatomical and mechanical parameters in gait initiation process in children

This study analyses the incidence of anatomical (mass, height, inertia) and mechanical (gravity) parameters on the duration of gait initiation, from a standing posture, in children. Twenty-one children, aged 4, 6 and 8 years, participated in the study. Experimental and theoretical values of the duration of gait initiation are compared. The experimental data are computed from children's gait executed on a force plate. The theoretical data are computed by using an inverted-pendulum model. The results show that (1) duration of gait initiation is independent of gait velocity, as it is in adults; (2) the experimental values are very close to the theoretical values. These findings suggest that children's biomechanical constants are determining factors for initiating movement. It is hypothesized that the capacity to combine and adapt properties of the body with dynamics of the context is acquired through practice of independent walking.