Studies on wild house mice VI: Differential effects of the Y chromosome on intermale aggression

The aim of this study is to determine the effects of different parts of the Y chromosome of wild house mice on aggression. To reach this goal, intercrosses were made between two selection lines for attack latency (SAL and LAL) and their congenic strains (SAL. LY and LAL. SY). This procedure resulted in F₁ hybrids that carried the same autosomes, but differed in their X chromosome and the two different parts of their Y chromosomes, the different parts of the Y chromosome being a recombining part called the pseudoautosomal region (PAR) and a non-recombining part (non-PAR). We conclude that both parts of the Y chromosome contribute slightly but significantly to variation in aggression. The major effect is accomplished by the PAR of the aggressive parent; a mirror effect is achieved by the non-PAR of the aggressive parent in interaction with the PAR. © 1994 Wiley-Liss, Inc.     

Studies on wild house mice iv: On the heredity of testosterone and readiness to attack

An attempt was made to determine the role of the Y chromosome in the development of aggression in wild house mice. The aggression-eliciting property of testosterone depends not only on circulating adult testosterone, but also on perinatal sensitization of the central nervous system to this steroid. Results of crosses between aggressive (SAL) and non-aggressive (LAL) mice indicate that adult plasma testosterone in these mice is determined by the autosomes, high testosterone levels being dominant over low levels. Conversely, the Y-chromosomal effect seems related to perinatal processes that sensitize the brain for testosterone.     

Computational and statistical methods for analyzing event-related potential data

Some computational and statistical techniques that can be used in the analysis of event-related potential (ERP) data are demonstrated. The techniques are fairly elementary but go one step further than do simple area measurement or peak picking, which are most often used in ERP analysis. Both amplitude and latency measurement techniques are considered. Principal components analysis (PCA) and methods for electromyographic onset determination are presented in detail, and Woody filtering is discussed briefly. The techniques are introduced in a nontechnical, tutorial review style. One and the same existing data set is presented, to which the techniques are applied, and practical guidelines for their use are given. The methods are demonstrated against a background of theoretical notions that are related to the definition of ERP components.     

Development and learning: a TASC-based perspective of the acquisition of perceptual-motor behaviors

The concepts of development and learning are discussed in terms of different theoretical orientations to the study of motor behavior. It is argued that although these concepts are commonly used to discuss various aspects of change across the life span, there is little agreement regarding the definition of these terms and even whether these are useful concepts for researchers studying change over time. A theoretical approach, the TASC-based approach is presented as an alternative account for examining change over time. The TASC label stands for a focus on particular tasks, adaptation and selection of behaviors as a function of constraints. This account is grounded in evolutionary theory and assumes that variability, selection, and adaptation are central to change over time within individuals. Emphasis is placed on the tasks individuals attempt to solve in achieving particular goals given the constraints of the local environment and the organism. An alternative manner to conceptualize the concepts of development and learning are presented within the TASC-based approach.     

The relation between infants' perception of catchableness and the control of catching

The authors studied how infants come to perceive and act adaptively by presenting 35 three- to nine-month-olds with balls that approached at various speeds according to a staircase procedure. They determined whether infants attempted to reach for the ball and whether they were successful (i.e., contacted the ball). In addition, the time and distance of the ball at the onset of the catching movements were measured for the successful interceptions. The authors found that not only catching skill but also the perceptual judgments of the catchableness improved with age; infants started to take their catching ability into account when judging whether a ball was catchable. Moreover, the authors observed that infants who made imprecise perceptual judgments were more likely to use a distance control strategy, whereas infants who made accurate perceptual judgments were more likely to use the more adaptive time strategy to control the catching movements. They conclude that the present study supports the proposal that, even in prelocomotor infants, the development of perception is intricately linked to or constrained by development in the visual control of action.     

Children's use of the bearing angle in interceptive actions

The authors investigated the effect of ball velocity and walking direction on children's adherence to the constant bearing angle (CBA) strategy. Children (N = 20) approached a moving ball to manually intercept it at a predefined target area. Results revealed that 10- to 12-year-olds adhered more than 5- to 7-year-olds to the CBA strategy. Younger children deviated more than older children from smaller angles of approach and lower ball velocities. The present findings suggest that younger children have difficulty adjusting to task requirements because they fail to couple walking velocity with ball velocity. The improvement seen with increasing age suggests that compliance with the CBA strategy may be attributed to older children's enhanced coincidence anticipation.     

Effects of experience on the coordination of internally and externally timed soccer kicks

The authors investigated differences in the soccer kick between 8 experienced and 10 less experienced participants in 2 different task conditions (kicking a stationary ball or a moving ball at a target). The experienced participants were more accurate than their less experienced counterparts, whereas there were no differences in maximum foot velocity between groups or between conditions. When compared with their performance in the stationary condition, participants kicked the moving ball with a smaller range of movement at the knee of the kicking leg, maintaining a proximodistal coordination pattern. Because of their significantly shorter knee-flexion phase, the participants in the experienced group displayed a significantly shorter time between initiation of the forward swing of the kick and ball contact than that of those in the less experienced group. The rapid knee flexion may have been a strategy of exploiting passive dynamics to increase accuracy rather than velocity. Members of both groups showed a proximodistal initiation sequence in the kicking leg, which suggests that players can acquire that coordination pattern with relatively little structured practice and that further practice leads to improvement possibly through the increased exploitation of passive dynamics.