Rita Cordovil

The influence of instructions and body-scaling as constraints on decision-making processes in team sports.

Abstract Team games conceptualized as dynamical systems engender a view of emergent decision-making behaviour under constraints, although specific effects of instructional and body-scaling constraints have yet to be verified empirically. For this purpose, we studied the effects of task and individual constraints on decision-making processes in basketball. Eleven experienced female players performed 350 trials in 1 vs. 1 sub-phases of basketball in which an attacker tried to perturb the stable state of a dyad formed with a defender (i.e. break the symmetry). In Experiment 1, specific instructions (neutral, risk taking or conservative) were manipulated to observe effects on emergent behaviour of the dyadic system. When attacking players were given conservative instructions, time to cross court mid-line and variability of the attackers trajectory were significantly greater. In Experiment 2, body-scaling of participants was manipulated by creating dyads with different height relations. When attackers were considerably taller than defenders, there were fewer occurrences of symmetry-breaking. When attackers were considerably shorter than defenders, time to cross court mid-line was significantly shorter than when dyads were composed of athletes of similar height or when attackers were considerably taller than defenders. The data exemplify how interacting task and individual constraints can influence emergent decision-making processes in team ball games.

Influence of age, sex and somatic variables on the motor performance of pre-school children

Abstract Background: Biological factors can affect the motor development process of children. However, the magnitude of these effects throughout the developmental process remains fairly unknown. Aim: To determine the influence of age, sex and selected somatic measures on the motor performance of pre-school children. Subjects and methods: Three hundred and sixty-seven pre-schoolers (172 boys and 195 girls), aged from 3–5 years old, were recruited from 10 public pre-schools located in the district of Viana do Castelo, Portugal. The children’s motor performance was assessed by five motor sub-tests of Peabody Developmental Motor Scales-2: grasping, visuo-motor integration, stationary, locomotion and object manipulation sub-tests. Age, sex, height, weight and BMI were considered as hypothetical predictors of motor performance. Pearson’s correlation test and multiple linear regression analysis were used to explore the magnitude of the relationship between motor sub-tests and the hypothetical predictors. Results: Depending on the motor sub-test and age group, the models predicted motor performance from a minimum of 3.6% to a maximum of 34.4%. Age in months and sex stood out as the main predictors of motor performance. Conclusions: The relationship between motor performance and selected biological factors varied with age and with the specificity of the motor test.

Perceiving affordances in rugby union

Abstract To succeed in competitive environments, players need to continuously adjust their decisions and actions to the behaviour of relevant others. Players’ interactions demand ongoing decisions that are constrained by what is previously defined (e.g., coaches’ prescriptions that establish ‘what’ to do) and by information that is available in the context and specifies not only ‘what’ the player should do, but also ‘how’, ‘when’ and ‘where’ . We describe what affordances emerge to the ball carrier as a consequence of changes in kinematic variables, such as interpersonal distances or distances to the nearest sideline. Changes in these variables determine whether and when different actions are possible. The ball carrier tended to perform a pass when the tackler was farthest from the sideline and the velocity of approach to the tackler did not seem to effect the ball carriers decision. In the few episodes where the ball carrier moved forward instead of passing the ball, he was mainly influenced by contextual information, such as the variability of the players’ distance to the nearest sideline. In sum, actors must be aware of the affordances of others that are specified by particular variables that become available just before decision-making.

Egocentric or allocentric frameworks for the evaluation of other people’s reachability

The adoption of egocentric and allocentric frameworks in the perception of other peoples reachability was investigated. In study 1, 24 adults (12 experienced and 12 inexperienced dealing with children) judged vertical reachability for themselves and for two children. In study 2, 37 parents judged vertical reachability for themselves and their children. Absolute errors (|estimate-actual reachability|), absolute percent errors (|1-judgement/actual reachability|×100), and error tendency (underestimations, right judgments, or overestimations) were calculated. Adults were quite accurate in perceiving their own reachability (absolute percent errors ranging from 2.20% in study 1 to 3.12% in study 2) and clearly less precise when estimating childrens reachability. Results indicated a tendency for adults to overestimate reachability of the younger child (study 1) and a tendency for parents to overestimate their childrens reachability (study 2). No correlation between judgement errors for the self and for the children in any of the studies was observed. Results support the existence of an allocentric and not an egocentric framework when evaluating other peoples affordances.

Adults' perception of children's height and reaching capability

This study investigated the influence of some characteristics of the task, the model, and the observer, in the estimation errors of adults while judging childrens affordances. One hundred and eighteen adults, divided in 4 height groups, estimated height and vertical reaching capability of 3 girls (3.55-, 4.74- and 7.06-years old), in the presence and in the absence of the model. Constant errors (CE) (estimation-real value), absolute percent errors (APE) (/1--estimation/real value/ x 100), and error tendency (underestimations, right judgments, or overestimations) were calculated. A model and a condition effect were verified on APE. APE for the younger model were greater than for the other models (p<0.001), and APE in the absence of the model were greater than in her presence (p<0.05). Generally, adults underestimated height (51.8% of underestimations vs. 32.3% of overestimations) and overestimated reachability (51.3% of overestimations vs. 37.7% of underestimations). The overestimation of reachability was more notorious for the younger model, which might reflect adults difficulty to consider the specificity of younger childrens body proportions. Actually, the overestimation bias may suggest that adults perceive young children as on the basis of adults geometrical proportions.

Perceiving children's behavior and reaching limits in a risk environment

The purpose of this study was to investigate the accuracy of parents perception of childrens reaching limits in a risk scenario. A sample of 68 parents of 1- to 4-year-olds were asked to make a prior estimate of their childrens behavior and action limits in a task that involved retrieving a toy out of the water. The action modes used for reaching, accuracy of estimates, and error tendency were investigated. Several morphological variables, walking experience, and swimming program experience were analyzed as predictors of maximum and estimated maximum reachability. Most children sat to retrieve the toy out of the water and fell in while attempting to grasp beyond their reaching limit. Nearly 80% of the parents correctly predicted their childrens behavior when the toy was unreachable. Parents were cautious in predicting their childrens maximum reachability (>50% underestimates). Mothers were more accurate than fathers in estimating their childrens reaching limit. The prediction of childrens capabilities was based partially on body dimensions and proportions.

Children's (in)dependent mobility in Portugal

OBJECTIVESnTo characterize childrens independent mobility in Portugal, by studying the influence of age, sex, school type (primary/secondary) and location (urban/rural). To explore associations between mobility licences and childrens actual independent mobility.nnnDESIGNnCross-sectional study of 1099 children between 8 and 15 years of age and their parents. Children attended primary (n=660, 49% boys, 69% urban) and secondary (n=439, 43% boys, 72% urban) schools.nnnMETHODSnThe Portuguese version of the child independent mobility survey (Policy Studies Institute, London) was completed. Parents reported the mobility licences granted to their children. Children reported their independent mobility on school journeys and on weekends. Differences were examined in mobility licences and independent mobility by sex, urban/rural setting and primary/secondary schools. Multiple logistic regression models examined the associations between different variables and actual independent mobility.nnnRESULTSnSecondary school children are granted more licences and have greater levels of independent mobility than primary school children. Only 21% of primary school children and 45% of secondary school children come home from school actively and independently. Overall, sex does not influence the licences granted to children in Portugal but boys have greater levels of independent mobility during the weekends than girls. Children in rural settings report engaging in more activities during the weekend. The number of mobility licences granted to the child was identified as predictor for actual independent mobility on school days and during the weekend.nnnCONCLUSIONSnPortuguese children lack independent mobility. Complementary qualitative research will be important to inform about the better practices to tackle this problem.

Motor profile of Portuguese preschool children on the Peabody Developmental Motor Scales-2: A cross-cultural study

This study was designed to examine the cultural sensitivity of the PDMS-2 for Portuguese preschool children aged 36-71 months. A total of 540 children (255 males and 285 females) from 15 public preschools of Viana do Castelo, Portugal, were assessed. Age and gender effects in motor performance were examined. Results indicated that PDMS-2 is valid instrument to differentiate Portuguese age groups. Girls presented higher scores than boys in the Grasping and Visuo-motor integration subtests and lower scores in the Object Manipulation subtest. Portuguese preschoolers performed above US norms on Grasping, Visual-motor integration, and Stationary subtests, and bellow on Locomotion and Object Manipulation subtests. Overall, Portuguese children showed better results on the Fine Motor Quotient comparing to the Gross Motor Quotient. These results underline different motor development profiles between Portuguese and American children.

The relationship between motor coordination and executive functions in 4th grade children

In the last decades, there has been a declining trend in different components of childrens motor capabilities and an increasing concern with cognitive skills, but the relationship between motor and cognitive domains remains uncertain. In this study, we aimed to (1) analyse the relationship between motor coordination (MC) and executive functioning, (2) verify the role of processing speed in this relationship and (3) examine the interaction between MC and task complexity. Ninety-six healthy 9- to 11-year-old were evaluated using the Körperkoordination Test für Kinder and the planning scale of the Cognitive Assessment System. The results showed moderate associations between the global composite of MC and executive functioning; however, it seems that processing speed plays an important role in this association. The results also show that children with high MC have better cognitive performances particularly in tasks with higher complexity.

The efficacy of safety barriers for children: absolute efficacy, time to cross and action modes in children between 19 and 75 months

We examined the efficacy of safety barriers by testing their capabilities to prevent or delay crossing. Children between 19 and 75 months tried to climb different barriers selected for their age group, which represented the most common types of panel and horizontal bars barriers available on the market. Success or failure in crossing, time to cross and crossing techniques were analysed. Barrier characteristics influenced its restraining efficacy. Childrens success rate varied between 10% and 95.3%. None of the barriers assured a considerable protective delay. Three major action modes were identified: head over waist (HOW), head and waist (HAW) and head under waist (HUW). Generally, children adopted the safer action mode, HOW, to cross most barriers. Younger children often adopted unstable action mode in barriers with crossable gaps. Although some standards might need to be re-evaluated, there are no childproof barriers. Barriers are time-delaying devices that cannot substitute supervision and education.