To reach or not to reach? Perception of body effectivities by young infants

Two experiments compared 6‐month‐old infants as they reach for an object. All were proficient reachers but with different levels of sitting ability. The object was presented at various distances, within and beyond reach of the infant. In the first experiment, the scaling of perceived reachability in infants with different postural abilities (i.e. non‐sitter, near‐sitter, and sitter infants) was explored. The second experiment investigated the role of proprioception in the scaling of perceived reachability by non‐sitter and sitter infants. In general, results suggest that perceived reachability is calibrated in relation to the degree of postural control achieved by the infant. Infants demonstrate a sense of their own situation in the environment as well as a sense of their own body effectivities. Both determine the execution, or non‐execution, of reaching for a distal object by young infants. Copyright © 1999 John Wiley & Sons, Ltd.     

Constraints on Arm Selection Processes When Reaching: Degrees of Freedom and Joint Amplitudes Interact to Influence Limb Selection

With an interest in identifying the variables that constrain arm choice when reaching, the authors had 11 right-handed participants perform free-choice and assigned-limb reaches at 9 object positions. The right arm was freely selected 100% of the time when reaching to positions at 30° and 40° into right hemispace. However, the left arm was freely selected to reach to positions at ?30° and ?40° in left hemispace 85% of the time. A comparison between free- and assigned-limb reaching kinematics revealed that free limb selection when reaching to the farthest positions was constrained by joint amplitude requirements and the time devoted to limb deceleration. Differences between free- and assigned-arm reaches were not evident when reaching to the midline and positions of ±10°, even though the right arm was freely selected most often for these positions. Different factors contribute to limb selection as a function of distance into a specific hemispace.     

A Modeling Study of Potential Sources of Curvature in Human Reaching Movements

The authors of this article suggest that the slight but consistent posture-dependent curvature of the spatial paths in the kinematic transformation between intrinsic and extrinsic coordinates may result in a systematic curvature of movements initially planned as straight-line trajectories toward the target. A kinematic planning model is presented that takes into account the anisotropy of the intrinsic and extrinsic transformation and tends to avoid movements that require excessive joint rotations by introducing slight deviations from a straight-line trajectory. Preliminary simulations showed reasonably good agreement with experimental data, especially considering that the current model is strictly based on kinematics. A quantitative analysis showed that the strategy used in the model achieves a favorable compromise between straight-line movements and angular joint changes: By slightly increasing the spatial length of the movement (i.e., by introducing curvature), an individual can greatly reduce the total amount of joint rotation required to produce the movement.     

Music Sight-Reading Skill in Flute Players

This article reports an investigation of factors related to music sight-reading skill. Flute players (N = 30) performed six tasks: (a) sight-reading standard music, (b) sight-reading random music, (c) recall of music notation, (d) recall of letters, (e) eye-performance span, and (f) choice reaction time for playing individual notes. Sight-reading ability was significantly correlated with eye-performance span (.85), and music recall (.80), but not with letter recall (-.39), thus replicating results of previous work with pianists. Sight-reading skill was correlated with choice reaction time to notes (- .54), and there was a significant partial correlation between sight-reading skill and eye-performance span, with music-reading ability controlled. These results are consistent with the idea that increased skill involves both the speed-up of individual processing stages, and an increase in the degree to which these stages operate in parallel.     

Training program in psychosocial intervention for high-risk infants and their families

A multidisciplinary training program for psychosocial intervention in the Neonatal Intensive Care Unit (NICU) was developed. The purpose of the program was to train mental health and health care professionals in a psychosocial preventive intervention model for high-risk infants and their families throughout the infants' hospital course in the NICU. The program was divided into modules that include assessment and intervention with the infant, parents, family, and larger caregiving environment. Over a 3-year period 40 trainees from 9 disciplines were trained. A randomized clinical trial was conducted which showed the positive effects of the intervention. A clinical service including inpatient and outpatient follow-up has been established in the NICU based on the psychosocial model developed from the training program.     

Transfer Variables in Tracking Skills

In the present work the effect of two task variables on transfer were studied: shape of the track-circular or triangular; and target speed-constant or variable. One or both of these variables was changed on transfer. Experimental conditions were (a) 10 preshift and 10 post-shift trials, and (b) 20 single-trial alternations of two tasks. 22 groups of 12 Ss each were tested. Condition (a) showed positive transfer with single variable change and zero or negative transfer with simultaneous change in two variables, and condition (b) annulled all transfer effects. Results are discussed in terms of commonality between tasks and receptor and perceptual anticipation.     

Notes and Comments the Role of Action Feedback in the Acquisition of Simple Motor Responses

The use of visual action feedback (AIF) in learning a simple motor response can sometimes be as effective as the more conventional terminal feedback (TIF) but sometimes leads to gross overshooting errors when AIF is removed. Both the amplitude of movement and the gain of the AIF have strong and systematic effects on the error in attempted reproductions. Percent overestimation increases linearly with fog. gain and decreases linearly with log. amplitude. This may be due to an intersensory effect in which visual and kinesthetic feedback sum to form a unitary impression of the movement on which subsequent attempts at reproduction are based.     

The Effect of Posture on Early Reaching Movements

Infants of about 5 months of age who have just mastered the ability to reach succeed more frequently in contacting an object when they are seated upright than when they are supine or reclined. That effect of posture disappears in the subsequent months. Whether that effect can be attributed either to insufficient muscular strength or to insufficient control over the mechanically unstable arm was the subject of the present investigation. Kinematics and electromyography (EMG) of reaching movements of 8 sitting and supine infants at 12, 16, and 20 weeks of age were recorded. Maximum levels of shoulder torque as well as kinematic stability measures were similar in both postures. Coactivation levels and the frequency of on-off switching of muscles turned out to be higher in the sitting than in the supine posture. The authors suggest that the difference in reaching behavior resulted from the degree of error in the feedforward control signal that was allowed by the different postures rather than either insufficient muscular strength or insufficient control over the mechanically unstable arm.     

Emotional interaction in a group of preterm infants at 3 and 6 months of corrected age

Twenty preterm infants (birthweight<1500 g) and 20 healthy fullterm infants were compared with respect to emotional interaction with their mothers in a face‐to‐face situation at 3 months of age and in a feeding situation at 6 months of age (ages corrected for preterm birth). The assessed outcome was analysed with respect to infant variables (group, gender, gestational age, birthweight and neonatal risk factors) and maternal variables (age, education and parity). The outcomes at 3 and 6 months of age were also compared with findings of Griffiths’ testing at 10 months of age. At 3 months of age, the findings reveal no significant difference between the two groups with respect to emotional interaction. Maternal variables are more important for this interaction than are infant variables. The mother's level of formal education has a significant impact in both groups. In the group of fullterm infants, significantly lower scores for interaction are obtained by first‐time mothers in comparison with multi‐parae mothers. At 6 months of age, the difference between fullterm and preterm infants is significant. The preterm infants and their mothers now relate to one another more poorly than is the case for the fullterm dyads. These findings suggest that the difficulties encountered by the preterm infant emerge with time. Emotional interaction at this age and the results of Griffiths’ testing 4 months later are significantly correlated. Copyright © 1999 John Wiley & Sons, Ltd.     

The effect of mother-infant skin-to-skin contact on plasma cortisol and β-endorphin concentrations in preterm newborns

The aim of this study was to assess the effect of mother-infant skin-to-skin contact on plasma β- endorphin and cortisol concentrations in stable, preterm infants on a newborn intensive care unit. Blood samples were obtained before and at the end of a 20-min period of skin-to-skin contact. Similarly paired samples, obtained at the same times and after the same interval, without skin-to- skin contact, were obtained on another day and served as controls. Both cortisol and β-endorphin concentrations fell significantly after the skin-to-skin session (cortisol: geometric mean change 66%, p=0.008; β-endorphin: geometric mean change 74%, p=0.002). There was also a significant fall in cortisol levels during the control session (geometric mean change 78%, p=0.02), in contrast to β-endorphin levels, in which there was no significant change. Analysis of variance showed that the fall in β-endorphin, but not the fall in cortisol, during the skin-to-skin session was significant when compared with the control session. These results emphasize the hormonal responsiveness of the preterm newborn to relatively minor interventions. We conclude that maternal skin-to-skin contact results in a significant reduction in circulating β-endorphin in the newborn; there was no evidence of any adverse effect.     

两种训练方法对幼儿在园欺负行为的影响

该研究为了减少幼儿在园欺负行为,采用情境讨论法、角色扮演法对36名中班幼儿和39名大班幼儿的欺负行为进行为期一个月的训练.结果发现:角色扮演法和情境讨论法对减少幼儿的在园欺负行为都产生了一定的影响,但角色扮演法对幼儿在园欺负行为的影响效果显著,而情境讨论法的影响效果不显著,同时这两种训练方法的影响效果之间无显著性差异;训练对中班和大班幼儿的欺负行为都起到了一定的矫正作用,中班幼儿的在园欺负行为下降水平略高于大班幼儿,但并没有达到显著性差异;训练对减少中班男生和大班女生的在园欺负行为更有效果.