Infants attend to what happens at the rim when they perceive containment

A series of experiments revealed that 9- and 12-month-old infants, in contrast to 6-month-olds, paid attention to what was happening at the rim of a container when a block arrived at this opening. The rim of an enclosure marks the boundaries of containment for an object, and thus specifies an important source of information with respect to the event. Infants actually observed a solid block that repeatedly lowered into a container in both the habituation phase and in the test phase. In the test phase, infants looked longer to events showing a block that miraculously passed through the opening, although colliding against the rim on one to three places than to the same event without collision. This effect occurred depending on the number of places on the rim the block collided against and the age of the infant. However longer looking times did not show up when the block collided against a flexible rim, deforming this rim and passed through. Together, these results indicate that infants sample information that is meaningful to the event they see and that it is not the perceptual discrepancy with respect to the habitation phase that drives their looking in the test phase

Adaptive and phase transition behavior in performance of discrete multi-articular actions by degenerate neurobiological systems

The identification of attractors is one of the key tasks in studies of neurobiological coordination from a dynamical systems perspective, with a considerable body of literature resulting from this task. However, with regards to typical movement models investigated, the overwhelming majority of actions studied previously belong to the class of continuous, rhythmical movements. In contrast, very few studies have investigated coordination of discrete movements, particularly multi-articular discrete movements. In the present study, we investigated phase transition behavior in a basketball throwing task where participants were instructed to shoot at the basket from different distances. Adopting the ubiquitous scaling paradigm, throwing distance was manipulated as a candidate control parameter. Using a cluster analysis approach, clear phase transitions between different movement patterns were observed in performance of only two of eight participants. The remaining participants used a single movement pattern and varied it according to throwing distance,thereby exhibiting hysteresis effects. Results suggested that, in movement models involving many biomechanical degrees of freedom in degenerate systems, greater movement variation across individuals is available for exploitation. This observation stands in contrast to movement variation typically observed in studies using more constrained bi-manual movement models. This degenerate system behavior provides new insights and poses fresh challenges to the dynamical systems theoretical approach, requiring further research beyond conventional movement models