Morphology and step-time parameters were recorded in 100 children between 15 and 36 months to investigate the relation between morphology and the walking pattern. A footfall method was used to register step-time parameters. Next, the differences in step-time parameters between four morphological classes were assigned with a multiple analysis of variance. We also performed stepwise linear regressions with a correction for walking experience, to examine the relation between detailed morphological measurements and step-time parameters. The results of these regressions show a significant relation between pelvis span/ankle spread ratio and the relative radii of gyration in the frontal plane of head and pelvis. It is hypothesized that the morphology of the head and pelvis plays a role in the coordination of the walking pattern.

This study is part of a research program that aims at a better understanding of the influence of individual morphological differences and physical growth on development of independent walking in toddlers. As morphometric and segment inertial parameters for toddlers aged between 15 and 36 months are indispensable for the mechanical analyses inherent to this purpose, parameter data were collected. The provided dataset of morphological and segment inertial parameters is a valuable tool for locomotor biomechanical modelling. Analysis of the parameter data showed that there are substantial changes of most segment inertial parameters across body length and body mass. In addition, a classification system was developed to categorize toddlers on the basis of morphometry, reflecting the segment inertial constitution of the child. A principal components analysis (PCA) was applied to define the variance in physique between the children. PCA resulted in three newly composed variables: the ' Axis of chubbiness ', the ' Axis of allometric growth ' and the ' Axis of relative limb length '. The three axes are plotted against each other, resulting in eight morphological classes. With this classification the morphotype of toddlers between 15 and 36 months can be specified and used for further research on their walking patterns.

Morphology and kinematic parameters were recorded for 31 children between 15 and 36 months to investigate the relation between morphology and the walking pattern. A full 3D gait analysis using a VICON motion system was performed to gather kinematic data. Next, the differences in kinematic parameters between four morphological classes were assigned with a multiple analysis of variance, with a correction for walking experience. Also stepwise linear regressions were performed, to examine the relation between detailed morphological measurements and kinematic parameters. The regression models showed relationships between kinematic parameters of the ankle, hip, thorax and morphology. All results indicated that the upper body played an important role in the coordination of the walking pattern, especially in the frontal plane.

In this paper, we present a structural equation approach to modelling infant behaviour in the Strange Situation. A model was developed on a Dutch data set, and was subsequently cross-validated for an American data set containing the original Ainsworth data. Model building is reported in some detail as no previous similar analyses of the Strange Situation exist in the literature. The latent variables in the preferred model are stranger wariness, minimization or deactivation of attachment concerns, and maximization or hyperactivation of attachment concerns. Stranger wariness influences only the subsequent behaviour towards the mother, and behaviour in the second reunion episode is dependent on the same mother behaviour in the first reunion episode, and not on other mother behaviours. Structural equation modelling behaviour in the Strange Situation is shown to provide further insight into the dynamics of the procedure.

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