Effects of Constraining Postural Sway During Upper-Limb Precision Aiming Task Practice in Individuals with Stroke.

Individuals post-stroke commonly demonstrate alterations in motor behavior with regard to both task performance and the motor strategies used in pursuit of task goals. We evaluated whether constraining postural sway (motor strategy) during practice would affect upper-limb precision aiming performance (task performance) and postural control adaptations. Adults with stroke stood on a force plate while immersed in a virtual scene displaying an anterior target.

Entropy as a Window Into Behavioral Phase Transitions: Unveiling Contextual Dynamics in Affordance-Based Reaching.

Prior work has demonstrated the presence of hysteresis effects in the control of affordance-guided behavior, in that behavioral transitions around a critical action boundary vary with directions of change in said action boundary. To date, research on this topic has overlooked the influence of the global context on these phenomena. We employ an affordance-based reaching task, whereby participants were asked to move a target to a goal by passing through one of two apertures (size variable or size constant).

Precision aiming performance with the paretic upper limb is associated with center of pressure patterns in individuals with chronic stroke.

Background: Individuals with stroke commonly demonstrate upper-limb sensorimotor impairments. Upper-limb tasks occur against a background level of postural control and thus require a flexible postural control system to facilitate performance. Anterior precision aiming tasks, for example, benefit from lower medial-lateral (ML) center of pressure (COP) fluctuations (where increased fluctuations erode performance) relative to anterior-posterior (AP) fluctuations (where increased fluctuations do not strongly influence performance).

The Effect of Navigation Demand on Decision Making in a Dynamic, Sport-Inspired Virtual Environment.

Athletes commonly make decisions about the passability of closing gaps when navigating sport environments. This study examined whether increased temporal pressure to arrive at a desired location modifies these decisions. Thirty participants navigated toward a waypoint in a virtual, sport-inspired environment.

A cluster phase analysis for collective behavior in team sports.

Collective behavior can be defined as the ability of humans to coordinate with others through a complex environment. Sports offer exquisite examples of this dynamic interplay, requiring decision making and other perceptual-cognitive skills to adjust individual decisions to the team self-organization and vice versa. Considering players of a team as periodic phase oscillators, synchrony analyses can be used to model the coordination of a team.

The Stance Leads the Dance: The Emergence of Role in a Joint Supra-Postural Task.

Successfully meeting a shared goal usually requires co-actors to adopt complementary roles. However, in many cases, who adopts what role is not explicitly predetermined, but instead emerges as a consequence of the differences in the individual abilities and constraints imposed upon each actor. Perhaps the most basic of roles are and .

Multi-scale interactions in interpersonal coordination.

Background: Interpersonal coordination is an essential aspect of daily life, and crucial to performance in cooperative and competitive team sports. While empirical research has investigated interpersonal coordination using a wide variety of analytical tools and frameworks, to date very few studies have employed multifractal techniques to study the nature of interpersonal coordination across multiple spatiotemporal scales. In the present study we address this gap.

Visual influences on postural and manual interpersonal coordination during a joint precision task.

We investigated whether the interpersonal postural coordination that occurs during a joint supra-postural, manual precision task is driven by the constraints of the task, or, instead results from visual entrainment to the movements of a co-actor. Participants were instructed to coordinate their finger movements under conditions where participants could see others' whole-body movements or could only see the results of the other's actions. Participants' finger and torso movements were recorded.

Joint action in a cooperative precision task: nested processes of intrapersonal and interpersonal coordination.

The authors determined the effects of changes in task demands on interpersonal and intrapersonal coordination. Participants performed a joint task in which one participant held a stick to which a circle was attached at the top (holding role), while the other held a pointer through the circle without touching its borders (pointing role). Experiment 1 investigated whether interpersonal and intrapersonal coordination varied depending on task difficulty.

Perceiving action boundaries: learning effects in perceiving maximum jumping-reach affordances.

Coordinating with another person requires that one can perceive what the other is capable of doing. This ability often benefits from opportunities to practice and learn. Two experiments were conducted in which we investigated perceptual learning in the context of perceiving the maximum height to which an actor could jump to reach an object.

Perceiving affordances for joint actions.

Two individuals acting together to achieve a shared goal often have an emergent set of afforded behavioral possibilities that may not easily reduce to either acting alone. In a series of experiments we examined the critical boundaries for transitions in behavior for individuals walking through an aperture alone or alongside another actor as a dyad. Results from experiment 1 indicated that an intrinsically scaled critical boundary for behavioral transitions was different in individuals than in dyads performing a similar task.