INFLUENCE OF EXTERNAL RISK FACTORS ON ALPINE SKIING INJURIES IN RECREATIONAL SKIERS

The main goal of this study was to identify potential external risk factors for injury in recreational skiers through a survey questionnaire. Subjects were divided into injured skiers and a control group who never had an injury. Injured skiers (N=212) answered questions that helped define potential risk factors. The control group (N=206) completed the same questionnaire but without questions about injury. Common questions were used to determine the possibility of injury using Chi-Square test, and additional questions were used to determine the influence on injury severity using Fisher’s test. An analysis of external factors showed that formal ski school was not statistically related to the possibility and severity of injury, but significantly increased knowledge of skiing. Skiing with another person did not decrease the possibility of injury but did increase the severity of injury. Visibility, field of vision, condition of the slope, temperature, and weather conditions are not statistically related to injury severity, but when combined, they could be an important factor in the possibility of injury.

Understanding risks of refractive error among Chinese children amidst pandemic disruptions: results from a rapid survey

Background Despite effectiveness in delaying the spread of the pandemic, frequent and extended disruption to children’s livelihoods have fomented new norms in which learning routines encounter immense change. In particular, increased sedentary e-learning engagement with electronic screens and exposure to stressful circumstances are likely to pose adverse risks for children’s vision development. Methods This present study examines the link between near-sighted refractive error, and sedentary exposure to electronic screens, psychosocial stress level, and outdoor activities. A Rapid Survey Methodology (RSM) design was utilized to collect information on subject’s vision condition, sedentary electronic screen use, and level of psychosocial stress, in addition to detailed socio-demographic background characteristics. Results This study involves 2234 subjects enrolled in 1st to 6th grade in primary schools. Every 1 diopter hour increase in electronic screen use per day is associated with 1.036 OR (95% CI =1.024–1.047, p-value< 0.050), while every 1 h • W m− 2 sr− 1 of illuminance-weighted electronic screen use per day is associated with 2.285 OR (95% CI =1.829–2.855, p-value< 0.050) increased likelihood of near-sighted refractive error. Higher level of psychosocial stress is associated with 2.441 OR (95% CI =1.870–3.187, p-value< 0.050) and 2.403 OR (95% CI =1.839–3.141, p-value< 0.050) increased likelihood of near-sighted refractive error. Frequency of outdoor activity is not significantly associated with increased likelihood of near-sighted refractive error (p-value> 0.050). Conclusions Findings in this study show that many factors, including grade level and prior vision condition, contribute to increased risks of near-sighted refractive error during the COVID-19 pandemic. More strikingly, pandemic-related behavioral modifications such as lengthy sedentary electronic screen use and elevated levels of psychosocial stress are two critical channels affecting children’s eye health.

Influence of visual feedback, hand dominance and sex on individuated finger movements

The ability to perform individual finger movements, highly important in daily activities, involves visual monitoring and proprioception. We investigated the influence of vision on the spatial and temporal control of independent finger movements, for the dominant and non-dominant hand and in relation to sex. Twenty-six healthy middle-aged to old adults (M age = 61 years; range 46–79 years; females n = 13) participated. Participants performed cyclic flexion–extension movements at the metacarpophalangeal joint of one finger at a time while keeping the other fingers as still as possible. Movements were recorded using 3D optoelectronic motion technique (120 Hz). The movement trajectory distance; speed peaks (movement smoothness); Individuation Index (II; the degree a finger can move in isolation from the other fingers) and Stationarity Index (SI; how still a finger remains while the other fingers move) were extracted. The main findings were: (1) vision only improved the II and SI marginally; (2) longer trajectories were evident in the no-vision condition for the fingers of the dominant hand in the female group; (3) longer trajectories were specifically evident for the middle and ring fingers within the female group; (4) females had marginally higher II and SI compared with males; and (5) females had fewer speed peaks than males, particularly for the ring finger. Our results suggest that visual monitoring of finger movements marginally improves performance of our non-manipulative finger movement task. A consistent finding was that females showed greater independent finger control compared with males.

Allocation of Attention to Visual and Nonvisual Perceptual Channels by Marksmen During Aiming: Skill-Level Differences

This study examined attention allocation in 30 marksmen categorized into 3 skill levels ranging from expert to novice. Each shooter performed 336 shooting trials. Half of the trials were performed under an occluded-vision condition and the rest under regular, unoccluded conditions. Immediately after completion of a random subset of shots (96 trials), shooters estimated the actual location of each shot, and on a random subset of trials (48 trials), shooters gave retrospective verbal reports. A mixed 3 × 2 factorial analysis of variance revealed that the expert marksmen performed and estimated their shots more accurately than the intermediate and novice marksmen, the intermediates performed like the experts under the full-vision condition and like novices under the occluded-vision condition, and the experts reported attending more to nonvisual information while they estimated their shots than did the novices. The findings advance our understanding of the mechanisms mediating expertise.

Aplicativo Android para classificação de fitas indicadoras de pH

<p>PH is one of the main quality indicators used in several industries such as food, beverage and water treatment. Some pH measurements methods are more affordable than others and can be easily used by anyone. The pH test strips can be highlighted as one of the best techniques. At the same time, this kind of analysis relies on the human vision condition that may be compromised in some cases due to aging, eye fatigue or vision-related diseases. This work presents the development of an Android app capable of classifying a pH strip according to its reference chart using image processing techniques.</p>

Validation of the International Reading Speed Texts in a Canadian Sample

Purpose: The purpose of these studies are (1) to validate the IReST in an English-speaking Canadian sample; and (2) examine how reading comprehension questions and reduced visual acuity effect reading speed on the IReST.Materials &amp; Methods: Study 1: Canadian English speakers (n=25) read all 10 IReST following the procedures used in the original IReST validation. Study 2: Canadian English speakers (n=50) read all 10 IReST, half with normal/corrected-to-normal vision and half with reduced visual acuity, and were asked reading comprehension questions.Results: No significant differences were found between Canadian sample and the published IReST values (in all cases p&gt;.05, Mdiff=[-5.30,11.43], Cohen’s d=[-.15, .27], Bayes Factors=[0.41,0.09]). Assessing reading comprehension with multiple choice questions on the IReST significantly reduced reading speeds in the normal vision condition (Mdiff=25.3, 95% CI=[-16.7,-34.1]) and in the simulated impairment condition (Mdiff=59.3, 95% CI [-47.7,-71]).Conclusions: The IReST is a valid measure that can be used to assess reading speed in a Canadian English speaking sample. If researchers/clinicians wish to assess both reading speed and comprehension, using multiple choice reading comprehension questions, then the values provided by the IReST will likely overestimate an individual’s true reading speed in individuals with normal/corrected-to-normal vision and reduced visual acuity.

Can Stroboscopic Training Improve Time-to-Collision Judgments of Laterally Moving Objects?

We investigated whether effects of stroboscopic training on time-to-collision (TTC) judgments depend on the optical flow pattern. Prior research showed that TTC judgments of lateral motion reflected benefits of stroboscopic viewing (Ballester, Huertas, Uji, & Bennett, 2017; Smith & Mitroff, 2012), but TTC judgments of approach motion did not reflect such benefits (Braly & DeLucia, 2017). This discrepancy may be due to differences in the optical flow patterns between lateral and approach motion. In lateral motion, the optical flow pattern is linear; the change in the object’s optical position is the same throughout its trajectory. In approach motion, the optical flow pattern is non-linear; the change in the object’s optical size increases as it gets closer to the eye. It has been proposed that this difference in the optical flow pattern underlies the greater accuracy of TTC judgments that occur with lateral motion compared to approach motion (Schiff & Oldak, 1990). In the current study, we measured effects of stroboscopic viewing on TTC judgments of lateral motion using identical methods in our prior study of approach motion. Although prior research demonstrated potential benefits of stroboscopic viewing for judgments of lateral motion, the stimulus was visible when the response was made. Prior demonstrations that the object’s trajectory (and thus nature of the optic flow) affects TTC judgments were demonstrated with prediction-motion (PM) tasks in which the object disappeared before a response was made. The two types of tasks are putatively based on different visual information and cognitive processes (Tresilian, 1995). Thus, we used a PM task in the current study. Participants viewed computer simulations of an object that moved laterally toward a target and then disappeared. They pressed a mouse button at the exact time that they thought the object would hit the target. Mean constant error and variable error of TTC judgments were compared among intervention conditions of stroboscopic training (5 minutes in duration), continuous viewing (practice without feedback), and a control filler task. Performance was measured during four sessions—pre-test, intervention, immediately after intervention, and 10 minutes after intervention. When distance was far, participants in the stroboscopic intervention condition were, on average, less variable at the 10-minute posttest compared to the pretest. Although the difference was not statistically significant, it is noteworthy that performance did not significantly degrade over time as it did in the filler condition, and in our prior study of approach motion (Braly & DeLucia, 2017). Such results suggest that stroboscopic training can protect against performance degradation over time (due to fatigue, monotony, etc). A protective effect also was observed in the continuous vision condition (performance did not degrade over time); however, observations of the means suggest that performance would have degraded over time if longer training was completed. When TTC was 3.0 s, performance in the stroboscopic intervention was not more variable in the immediate posttest compared to the pretest and, more importantly, was less variable at the ten-minute posttest (although p = 0.0515). Our results show that under specific conditions (when TTC was 3.0 s; when distance was far) stroboscopic training can protect against performance degradation over time; that is, variable error did not increase. Such protective effects of stroboscopic training were not observed in our earlier study of approach motion (Braly & DeLucia, 2017). Neither study showed a significant effect of stroboscopic training on constant error. The implication is that the effects of stroboscopic training depend on the nature of the optical flow pattern. In future studies, it is important to systematically determine the conditions under which stroboscopic training can improve performance. Results will have important implications for traffic safety and for driver training programs.

The Roles of Different Spatial Frequency Channels in Real-World Visual Motion Perception

Speed perception is an important task performed by our visual system in various daily life tasks. In various psychophysical tests, relationship between spatial frequency, temporal frequency, and speed has been examined in human subjects. The role of vision impairment in speed perception has also been previously examined. In this work, we examine the inter-relationship between speed, spatial frequency, low vision conditions, and the type of input motion stimuli in motion perception accuracy. For this purpose, we propose a computational model for speed perception and evaluate it in custom generated natural and stochastic sequences by simulating low-vision conditions (low pass filtering at different cutoff frequencies) as well as complementary vision conditions (high pass versions at the same cutoff frequencies). Our results show that low frequency components are critical for accurate speed perception, whereas high frequencies do not play any important role in speed estimation. Since perception of low frequencies may not be impaired in visual acuity loss, speed perception was not found to be impaired in low vision conditions compared to normal vision condition. We also report significant differences between natural and stochastic stimuli, notably an increase in speed estimation error when using stochastic stimuli compared to natural sequences, emphasizing the use of natural stimuli when performing future psychophysical studies for speed perception.

Sensorimotor integration of vision and proprioception for obstacle crossing in ambulatory individuals with spinal cord injury

Skilled walking, such as obstacle crossing, is an essential component of functional mobility. Sensorimotor integration of visual and proprioceptive inputs is important for successful obstacle crossing. The objective of this study was to understand how proprioceptive deficits affect obstacle-crossing strategies when controlling for variations in motor deficits in ambulatory individuals with spinal cord injury (SCI). Fifteen ambulatory individuals with SCI and 15 able-bodied controls were asked to step over an obstacle scaled to their motor abilities under full and obstructed vision conditions. An eye tracker was used to determine gaze behaviour and motion capture analysis was used to determine toe kinematics relative to the obstacle. Combined, bilateral hip and knee proprioceptive sense (joint position sense and movement detection sense) was assessed using the Lokomat and customized software controls. Combined, bilateral hip and knee proprioceptive sense in subjects with SCI varied and was significantly different from able-bodied subjects. Subjects with greater proprioceptive deficits stepped higher over the obstacle with their lead and trail limbs in the obstructed vision condition compared with full vision. Subjects with SCI also glanced at the obstacle more frequently and with longer fixation times compared with controls, but this was not related to proprioceptive sense. This study indicates that ambulatory individuals with SCI rely more heavily on vision to cross obstacles and show impairments in key gait parameters required for successful obstacle crossing. Our data suggest that proprioceptive deficits need to be considered in rehabilitation programs aimed at improving functional mobility in ambulatory individuals with SCI.NEW & NOTEWORTHY This work is unique since it examines the contribution of combined, bilateral hip and knee proprioceptive sense on the recovery of skilled walking function, in addition to characterizing gaze behavior during a skilled walking task in people with motor-incomplete spinal cord injury.

Sensory Interactions for Head and Trunk Control in Space in Young and Older Adults During Normal and Narrow-Base Walking

Fifteen young (20–30 years old) and 15 older (>65 years old) healthy participants were recruited to investigate age-related differences in head and trunk control under suboptimal vestibular conditions (galvanic vestibular stimulation, or GVS) and vision conditions during normal and narrow-based walking. Head-roll velocity decreased in the blurred-vision condition and marginally increased with GVS in older but not in young participants. Head pitch increased, whereas head-roll velocity decreased in narrow-base walking. Trunk pitch, trunk-pitch velocity, and gait speed increased with GVS, whereas trunk-pitch velocity and gait speed decreased in narrow-base walking. Marginally increased head-roll velocity in the older participants possibly suggests decreased integrative ability of the central nervous system in elderly people. The changes in head control during narrow-base walking may be an attempt to simplify the interpretation of the vestibular signal and increase otolith sensitivity. The complexity of controlling the trunk in the mediolateral direction was suggested by different strategies used for trunk control in different conditions.