Partner Effects May Be Weaker Than We Thought. What Does That Mean for Relationship Science?

In relationship science, researchers focus on studying interpersonal effects among dyads or romantic couples, as well as common relationship outcomes like quality, satisfaction, and commitment. To do so, a statistical analysis known as the actor-partner interdependence model is used to examine dyadic effects, such as how an individual’s variable may affect the other member of the dyad. Within this model, there are actor and partner effects. An actor effect can be defined as the effect of partner 1’s independent variable on their own dependent variable. A partner effect can be defined as the effect of partner 1’s independent variable on partner 2’s dependent variable. As partner effects are assumed to be highly important within dyads, this recent research poses a potentially large problem for all relationship scientists. My research seeks to further assess whether partner effects are significant contributors to dyadic data analysis or whether relationship researchers may be overemphasizing their importance

An Attempt to Determine the Effects of Lateral Dominance on Reading Ability

Statement of the Problem: The problem is to survey the available recent research and discussion to determine the effects of lateral dominance on how well our children read. This is a problem of conflicting concepts, a controversial issue which both sides have presented for over twenty-five years, the possible relationship between cerebral dominance and laterality of function. Purpose of the Study: The purpose of this study is for the writer to attempt to review all material, pertinent to the importance of laterality in improving children\u27s reading ability, to be found in current literature, preferably of the last five years. Interest in this problem has been shared by many teachers in the past and is currently shown by those who seek a possible answer to some of their reading problems in the intermediate as well as in the primary grades. Therefore, it is the writer\u27s intent to satisfy a desire to find to what extent, if any, lateral dominance does affect reading ability

Virtual Reality as a Medium for Sensorimotor Adaptation Training and Spaceflight Countermeasures

With the upcoming shift to extralong duration missions (1 year) aboard the ISS, sensorimotor adaptations during transitory periods inandout of microgravity are more important to understand and prepare for. Advances in virtual reality technology enables everyday adoption of these tools for entertainment and use in training. Experiencing virtual environments (VE) allows for the manipulation of visual flow to elicit automatic motor behavior and produce sensorimotor adaptation (SA). Recently, the ability to train individuals using repeatable and varied exposures to SA challenges has shown success by improving performance during exposure to a novel environment (Batson 2011). This capacity to 'learn to learn' is referred to as sensorimotor adaptive generalizability and, through the use of treadmill training, represents an untapped potential for individualized countermeasures. The goal of this study is to determine the feasibility of present head mounted displays (HMDs) to produce compelling visual flow information and the expected adaptations for use in future SA treadmillbased countermeasures. Participants experience infinite hallways providing congruent (baseline) or incongruent visual information (half or double speed) via HMD while walking on an instrumented treadmill at 1.1m/s. As gait performance approaches baseline levels, an adaptation time constant is derived to establish individual timetoadapt (TTA). It is hypothesized that decreasing the TTA through SA treadmill training will facilitate sensorimotor adaptation during gravitational transitions. In this way, HMD technology represents a novel platform for SA training using offtheshelf consumer products for greater training flexibility in astronaut and terrestrial applications alike

Understanding the Effects of Spaceflight on Head-trunk Coordination during Walking and Obstacle Avoidance

Prolonged exposure to spaceflight conditions results in a battery of physiological changes, some of which contribute to sensorimotor and neurovestibular deficits. Upon return to Earth, functional performance changes are tested using the Functional Task Test (FTT), which includes an obstacle course to observe postflight balance and postural stability, specifically during turning. Aims: To quantify changes in movement strategies during turning events by observing the latency between headandtrunk coordinated movement. Hypothesis: It is hypothesized that subjects experiencing neurovestibular adaptations will exhibit headtotrunk locking ('en bloc' movement) during turning, exhibited by a decrease in latency between head and trunk movement. Sample: FTT data samples were collected from Shuttle and ISS missions. Samples were analyzed three times pre exposure, immediately postexposure (0 or 1 day post) and 2to3 times during recovery from the microgravity environment. Methods: Two 3D inertial measurements units (XSens MTx) were attached to subjects, one on the head and one on the upper back. This study focused primarily on the yaw movements about the subject's center of rotation. Time differences (latency) between head and trunk movement were calculated at two points: the first turn (Fturn) to enter the obstacle course (approximately 90 turn) and averaged across a slalom obstacle portion, consisting of three turns (approximately three 90 turns). Results: Preliminary analysis of the data shows a trend toward decreasing headtotrunk movement latency during postflight ambulation, after reintroduction to Earth gravity in Shuttle and ISS astronauts. Conclusion: It is clear that changes in movement strategies are adopted during exposure to the microgravity environment and upon reintroduction to a gravity environment. Some subjects exhibit symptoms of neurovestibular neuropathy ('en bloc movement') that may impact their ability to perform postflight functional tasks

An examination of risk and resource sharing behavior between LTL trucking companies and warehouse providers

Increased demand for third-party logistics providers who can offer multiple services to their customers has encouraged many entities to explore innovative ways to expand service offerings. The current research examines Class I LTL motor carriers who have expanded their services to include warehousing. While there are several ways to achieve a service expansion into warehousing, the current research focuses on firms who have elected to expand by creating a strategic alliance type relationship with an external warehouse provider. The research examines carriers attitudes about risk and resource sharing in the alliance relationship. The results indicate that carriers are moderately receptive to sharing resources with their warehouse partner and relatively less interested in sharing risks with the warehouse partner

Forecasting Sensorimotor Adaptability from Baseline Inter-Trial Correlations

One of the greatest challenges for sensorimotor adaptation to the spaceflight environment is the large variability in symptoms, and corresponding functional impairments, from one crewmember to the next. This renders preflight training and countermeasure development difficult, as a "one-size-fits-all" approach is inappropriate. Therefore, it would be highly advantageous to know ahead of time which crewmembers might have more difficulty adjusting to the novel g-levels inherent to spaceflight. This information could guide individually customized countermeasures, which would enable more efficient use of crew time and provide better outcomes. The principal aim of this work is to look for baseline performance metrics that relate to locomotor adaptability. We propose a novel hypothesis that considers baseline inter-trial correlations, the trial-to-trial fluctuations ("noise") in motor performance, as a predictor of individual adaptive capabilities

Identifying Head-Trunk and Lower Limb Contributions to Gaze Stabilization During Locomotion

The goal of the present study was to determine how the multiple, interdependent full-body sensorimotor subsystems respond to a change in gaze stabilization task constraints during locomotion. Nine subjects performed two gaze stabilization tasks while walking at 6.4 km/hr on a motorized treadmill: 1) focusing on a central point target; 2) reading numeral characters; both presented at 2m in front at the level of their eyes. While subjects performed the tasks we measured: temporal parameters of gait, full body sagittal plane segmental kinematics of the head, trunk, thigh, shank and foot, accelerations along the vertical axis at the head and the shank, and the vertical forces acting on the support surface. We tested the hypothesis that with the increased demands placed on visual acuity during the number recognition task, subjects would modify full-body segmental kinematics in order to reduce perturbations to the head in order to successfully perform the task. We found that while reading numeral characters as - compared to the central point target: 1) compensatory head pitch movement was on average 22% greater despite the fact that the trunk pitch and trunk vertical translation movement control were not significantly changed; 2) coordination patterns between head and trunk as reflected by the peak cross correlation between the head pitch and trunk pitch motion as well as the peak cross correlation between the head pitch and vertical trunk translation motion were not significantly changed; 3) knee joint total movement was on average 11% greater during the period from the heel strike event to the peak knee flexion event in stance phase of the gait cycle; 4) peak acceleration measured at the head was significantly reduced by an average of 13% in four of the six subjects. This was so even when the peak acceleration at the shank and the transmissibility of the shock wave at heel strike (measured by the peak acceleration ratio of the head/shank) remained unchanged. Taken together these results provide further evidence that the full body contributes to gaze stabilization during locomotion, and that its different functional elements can be modified online to contribute to gaze stabilization for different visual task constraints

INFLUENCE OF EXTERNAL FORCES ON THE CONTROL AND PERFORMANCE OF A MINIMUM TIME SHOULDER FLEXION TASK

INTRODUCTION AND METHODS We have been using planar mathematical models to simulate the task of a rapid bilateral arm raise and to obtain minimum movement time solutions. Here we report the effect of gravity (G), ground reaction force (GRF) and center of pressure (COP) location on the solutions of a three segment model. We modeled the arms as a rigid segment, the head, torso, upper and lower legs as a second rigid segment, and the feet as a third rigid segment. The shoulder and ankle joints were modeled as revolute pin joints. A nonlinear rotational spring and damper restrained the movement of the ankle joint within physiological limits. Joint muscle torques were generated through two idealistic torque generators. Torque history values (for each joint) were controlled by eight evenly spaced nodes, while intermediate values were obtained by linear interpolation. The foot to ground interaction was modeled with the use of two 2-D springs (nonlinear vertically, linear horizontally) and dampers. One set was attached at the toes and one at the heel. Thus, the feet were free to move off and slide along the ground depending on the dynamics of the simulation. The initial position was quiet erect stance with the arms and feet perpendicular to it. A variable step integrator was used for the forward simulations. The parameterized torque histories were optimized using a nonlinear optimization algorithm. We compared solutions with G, without G (free floating or attached to the ground), and with the COP location at the initial and final state proscribed to be either below the ankle joint or at the middle of the feet. This adjustment of the COP was accomplished by defining the initial and final orientation of the body segment. The arms and feet initial and final orientation, as well as the anthropometric parameters and strength limits of the model were held constant for all solutions. RESULTS AND CONCLUSIONS The overall performance and &ody kinematics were very similar and well within human subject experimental results, but the 1G condition revealed higher maximum arm angular velocity (8radsec) than the OG conditions (7 radsec). Although the 1G solution used maximum ankle torque, the heel moved up minimally (< 6 mm) only early in the stopping phase. On the other hand, although the OG free floating solution used minimal ankle torque values, there was maximum dorsiflexion followed by maximum plantarflexion. The 1G condition revealed significant plantar- and shoulder-flexion torques at the end of the movement that the OG attached to the floor model did not have. Finally, the two COP conditions produced opposite ankle torque coordination, a variability also observed during human subject experiments

Adaptive Changes in Sensorimotor Coordination and Motion Sickness Following Repeated Exposures to Virtual Environments

Virtual environments offer unique training opportunities, particularly for training astronauts and preadapting them to the novel sensory conditions of microgravity. Two unresolved human factors issues in virtual reality (VR) systems are: 1) potential "cybersickness", and 2) maladaptive sensorimotor performance following exposure to VR systems. Interestingly, these aftereffects are often quite similar to adaptive sensorimotor responses observed in astronauts during and/or following space flight. Initial interpretation of novel sensory information may be inappropriate and result in perceptual errors. Active exploratory behavior in a new environment, with resulting feedback and the formation of new associations between sensory inputs and response outputs, promotes appropriate perception and motor control in the new environment. Thus, people adapt to consistent, sustained alterations of sensory input such as those produced by microgravity, unilateral labyrinthectomy and experimentally produced stimulus rearrangements. The purpose of this research was to compare disturbances in sensorimotor coordination produced by dome and head-mounted virtual environment displays and to examine the effects of exposure duration, and repeated exposures to VR systems. The first study examined disturbances in balance control, and the second study examined disturbances in eye-head-hand (EHH) and eye-head coordination