Treacherous pavements:Paving slab patterns modify intended walking directions

Current understanding in locomotion research is that, for humans, navigating natural environments relies heavily on visual input; in contrast, walking on even ground in man-made obstacle and hazard-free environments is so highly automated that visual information derived from floor patterns should not affect locomotion and in particular have no impact on the direction of travel. The vision literature on motion perception would suggest otherwise; specifically that oblique floor patterns may induce substantial veering away from the intended direction of travel due to the so-called aperture problem. Here, we tested these contrasting predictions by letting participants walk over commonly encountered floor patterns (paving slabs) and investigating participants' ability to walk "straight ahead" for different pattern orientations. We show that, depending on pattern orientation, participants veered considerably over the measured travel distance (up to 8% across trials), in line with predictions derived from the literature on motion perception. We argue that these findings are important to the study of locomotion, and, if also observed in real world environments, might have implications for architectural design

Passing-by 'Ca va?' checks in clinic corridors

We have conducted a video-based field study on work interactions between staff members in the corridors of a hospital outpatient clinic in the French-speaking part of Switzerland. In this paper, we examine a specific mobile interactional configuration: passing-by interactions in which staff members get involved as they walk following close and parallel trajectories going in opposite directions. We also examine a specific conversational activity performed in the corridors: checks – introduced by the French expression “Ça va?” (Going okay?) – with which one staff member verifies that the situation of a colleague conforms to a routine state of affairs. Adopting the approaches of multimodal and conversation analysis, we point out features of the interactional configuration and the conversational activity under consideration that participants combine in some excerpts analyzed in the paper. Passing-by checks are practically accomplished, on the spot, through the sequential, embodied and embedded conduct of the staff members. We identify resources involved in building close but non- convergent trajectories, limiting interactional involvement, and coordinating talk and walk for a fleeting co-presence. The article contributes to the study of “on-the-move” contingent interactions as they happen in hospital corridors

Lower trunk motion and speed-dependence during walking

Abstract Background There is a limited understanding about how gait speed influences the control of upper body motion during walking. Therefore, the primary purpose of this study was to examine how gait speed influences healthy individual's lower trunk motion during overground walking. The secondary purpose was to assess if Principal Component Analysis (PCA) can be used to gain further insight into postural responses that occur at different walking speeds. Methods Thirteen healthy subjects (23 ± 3 years) performed 5 straight-line walking trials at self selected slow, preferred, and fast walking speeds. Accelerations of the lower trunk were measured in the anterior-posterior (AP), vertical (VT), and mediolateral (ML) directions using a triaxial accelerometer. Stride-to-stride acceleration amplitude, regularity and repeatability were examined with RMS acceleration, Approximate Entropy and Coefficient of Multiple determination respectively. Coupling between acceleration directions were calculated using Cross Approximate Entropy. PCA was used to reveal the dimensionality of trunk accelerations during walking at slow and preferred speeds, and preferred and fast speeds. Results RMS acceleration amplitude increased with gait speed in all directions. ML and VT trunk accelerations had less signal regularity and repeatability during the slow compared to preferred speed. However, stride-to-stride acceleration regularity and repeatability did not differ between the preferred and fast walking speed conditions, partly due to an increase in coupling between frontal plane accelerations. The percentage of variance accounted for by each trunk acceleration Principal Component (PC) did not differ between grouped slow and preferred, and preferred and fast walking speed acceleration data. Conclusion The main finding of this study was that walking at speeds slower than preferred primarily alters lower trunk accelerations in the frontal plane. Despite greater amplitudes of trunk acceleration at fast speeds, the lack of regularity and repeatability differences between preferred and fast speeds suggest that features of trunk motion are preserved between the same conditions. While PCA indicated that features of trunk motion are preserved between slow and preferred, and preferred and fast speeds, the discriminatory ability of PCA to detect speed-dependent differences in walking patterns is limited compared to measures of signal regularity, repeatability, and coupling.</p

ADVANCES IN BALANCE AND BIOFEEDBACK MEASUREMENT: THE CASE FOR HEALTH-BASED, POSTURAL SERIOUS GAMES

Health games are increasingly seen as a means to address issues from therapy and rehabilitation. Yet, as a transformative technology, rarely have such games been explored or exploited to assist research into pathologies. Serious games for research (SGR) to uncover pathologies would allow clinicians to develop new differential diagnostics while providing a positive experience for the subject. This paper is not about game design; nevertheless it presents an outlook to considerations that could be taken forward when developing health-based SGRs for pathomechanics, etiopathogenesis and biofeedback. This work relates to preliminary studies on balance challenges manifested in pathologies of the central nervous system. As technology advancements seek to augment human sensory contact between virtual and real worlds this may impact on how virtual environments are used and designed in future. As a consequence heightened sensory (or lack of thereof) may result in falls, for example users with vestibular disorder – because postural stability is a key aspect of motor ability that allows individuals to sustain and maintain the desired physical position of their body Here, our investigation is specific to functional correspondence of the incidental properties in human body sway between healthy subjects and subjects with dyslexia. Our early results suggest postural sway between healthy subjects and those with mild disorders can be distinguished

Context-specific adaptation of vertical vergence to correlates of eye position

AbstractVertical phoria (vertical vergence in the absence of binocular feedback) can be trained to vary with non-visual cues such as vertical conjugate eye position, horizontal conjugate eye position and horizontal vergence. These prior studies demonstrated a low-level association or coupling between vertical vergence and several oculomotor cues. As a test of the potential independence of multiple eye-position cues for vertical vergence, context-specific adaptation experiments were conducted in three orthogonal adapting planes (midsagittal, frontoparallel, and transverse). Four vertical disparities in each of these planes were associated with various combinations of two specific components of eye position. Vertical disparities in the midsagittal plane were associated with horizontal vergence and vertical conjugate eye position; vertical disparities in the frontoparallel plane were associated with horizontal and vertical conjugate eye position; and vertical disparities in the transverse plane were associated with horizontal vergence and horizontal conjugate eye position. The results demonstrate that vertical vergence can be adapted to respond to specific combinations of two different sources of eye-position information. The results are modeled with an association matrix whose inputs are two classes of eye position and whose weighted output is vertical vergence

Humanoid Robots

For many years, the human being has been trying, in all ways, to recreate the complex mechanisms that form the human body. Such task is extremely complicated and the results are not totally satisfactory. However, with increasing technological advances based on theoretical and experimental researches, man gets, in a way, to copy or to imitate some systems of the human body. These researches not only intended to create humanoid robots, great part of them constituting autonomous systems, but also, in some way, to offer a higher knowledge of the systems that form the human body, objectifying possible applications in the technology of rehabilitation of human beings, gathering in a whole studies related not only to Robotics, but also to Biomechanics, Biomimmetics, Cybernetics, among other areas. This book presents a series of researches inspired by this ideal, carried through by various researchers worldwide, looking for to analyze and to discuss diverse subjects related to humanoid robots. The presented contributions explore aspects about robotic hands, learning, language, vision and locomotion

Multisensory integration in complex rhythmic motor tasks

This publication-based thesis aimed to shed further light on the contributions of visual and auditory information to the execution of complex rhythmic motor tasks. To this end, a series of three empirical studies was designed. The first two studies were conducted in the experimental setting of long jumping – a task that does not only require high precision but also high velocity to leap as far as possible. Within the first study, we aimed to examine visual regulation during the long jump run-up using portable eye-tracking technology. Previous research on the topic of visual regulation in long jumping has identified a universal instance in participants’ gait behavior which introduces a rapid decrease in step variability. Since then, this parameter was considered synonymous with the (gait-based) onset of visual regulation. However, an investigation of actual visual behavior by means of direct measures was still pending to date. Hence, the first study was designed to identify a potential equivalent to the gait-based parameter within participants’ gaze behavior. Results revealed that the moment of the longest gaze on the take-off board coincided with the occurrence of the well-established gait parameter. Given that i) the gait-based visual regulation parameter has been associated with a reduction in footfall variability and ii) current research advocates the idea that fixations of longer duration facilitate motor actions, one might speculate that the longest gaze on the take-off board might as well serve the reduction of movement variability. While the parameter of visual regulation could be characterized in more detail within the first empirical investigation, the impact of other modalities has been neglected so far. However, current research is promoting the idea that, apart from visual information, auditory information might as well be crucial for the execution of motor tasks. ..

VESTIBULAR FUNCTION AND SPORTS-RELATED CONCUSSION: AN EXPLORATORY INVESTIGATION OF THE CONSEQUENCES OF SPORTS RELATED CONCUSSION ON VESTIBULAR FUNCTION AND OUTCOMES

Sports-related concussions (SRC), or mild traumatic brain injuries that occur as a result of sports or athletic participation, are said to affect approximately 300,000 young adults and 1.4 million youth athletes in the United States on an annual basis. SRC create a significant burden on the health care system by generating an estimated $60 billion dollars in direct and indirect costs in 2000. In addition to the financial burden these injuries create, they additionally impose both short- and long-term effects for those effected and their overall health. Among the many effects of concussions are physical signs as symptoms such as headache, dizziness, emotional/behavioral changes and coordination issues. Traditional diagnosis strategies rely on the individual’s self-report of experienced symptoms. In addition to symptoms, it is well documented that systems within the body are affected by these injuries and manifest in various functional deficits. Among these systems and deficits are those to the vestibular system, which is the system largely responsible for maintaining upright postural stability or balance and the stabilization of gaze during head movements, both crucial in athletic participation. These functions are mediated by the vestibulospinal reflex (VSR) and the vestibulo-ocular reflex (VOR). Advances in technology have made it possible to measure function of these reflexes and identify potential deficits to the system. These advances provide clinicians objective methods of measuring function and may improve current clinical practice and concussion management strategies including better return to play criteria. The primary purpose of this dissertation was to investigate how measures of vestibular function are related to time to medical clearance in athletes with a recent SRC. This dissertation also sought to establish normative estimates for VOR function and explore the relationship between VSR and VOR measures of function. Further, the relationship between objective measures of VSR and VOR function and self-reported symptoms and function was investigated. To achieve this purpose, several aims were investigated. The first aim sought to establish normative values for the DVAT and GST in collegiate athletes and explore the effect of sport, sex, and concussion history on VOR assessments. The second aim explored potential relationships between the Concussion Balance Test (COBALT), Dynamic Visual Acuity Test (DVAT), Gaze Stabilization Test (GST), and self-reported vestibular symptoms in collegiate athletes with and without a history of concussion. The final aim sought to explore potential predictors of prolonged recovery in a sample of adolescent and young adult athletes who have reported to a concussion clinic after sustaining an SRC. This exploratory investigation identified predictors, relative to vestibular function and other factors that influenced the time to recovery. Identified predictors of recovery included the number of days from the injury to the initial visit to the clinic, the number of visits from initial visit to medical clearance, the number of days to a successful COBALT completion. The results of this dissertation begin to provide more information regarding vestibular function as it relates to SRC as well as identifying factors that may be modifiable to improve outcomes. First, through the establishment of normative estimates of vestibular function, it was discovered that there are differences in normative vestibular function based on sports participation. Thus, it may be suggested that vestibular function may be improved based on the requirements and nature of the sport and can be improved with practice. Additionally, the standards for returning to play based on vestibular function should be unique to the activity an athlete is return. Additionally, understanding the relationships between measures of vestibular function may help in the identification of the most efficacious multi-faceted assessment strategy. Finally, identifying predictors of prolonged recovery relative to the vestibular function can aid in improving outcomes. Thus, further justifying the need for more comprehensive assessments