Geographical information is connected to everyday life in many ways. Web cartography has made geospatial data more available to the public. In the next few years, the average age of the population ...will be over 51 years, with more than 15% of the population over the age of 65 years. The fact that the senior population is increasing suggests that online mapping and map viewer design should be aware of the senior population's visual restrictions, as well as restrictions of other potential map users, including colour-vision-impaired users. This paper describes the senior population's visual restrictions that can be compared with colour-vision-impaired users and provides guidelines with regard to online mapping and map viewer design for this growing segment of the elderly population.
The main purpose of this study was to investigate the development of the head stabilization in space strategy (HSSS) during various locomotor tasks in 3- to 8-year-old children and adults. The ...contribution of visual factors to the HSSS was also examined by applying peripheral visual restriction, stroboscopic visual motion cue restriction, and darkness. The kinematics of the head and trunk rotations (pitch, yaw, and roll) were analyzed by means of an optical TV-image processor (ELITE system). For each of the three angular components, an appropriate "head anchoring index" was defined in order to compare the HSSS with a head stabilization on the trunk strategy. Head-trunk correlation rates were also calculated for each angular component in order to evaluate the head-trunk stiffness. The development of head-trunk coordinations during locomotion under normal vision can be said to involve at least three main periods. The first period occurs from the age of 3 to 6 years, when the HSSS is adopted only while walking on the flat ground. While walking on narrow supports, children in this age-group rather tend to increase the head-trunk stiffness, especially at 6 years of age. The second period includes 7- to 8-year-old children. Children of this age become able to adopt the HSSS while walking on narrow supports. During this period, the HSSS is associated with a large decrease in the head-trunk correlations. Lastly, in adulthood the HSSS is commonly adopted but specifically involves the roll component associated with the lateral body oscillations while walking. Vision was found to have little influence on children's HSSS while walking, whatever their age. Moreover, darkness induces an increase in the efficiency of the HSSS in adults. This confirms that the HSSS is the most appropriate strategy available for dealing with an increase in the level of equilibrium difficulty and may reflect a "top-down" organization of the postural control while walking. These results also suggest that the HSSS may be mainly of vestibular origin and presumably serves to facilitate the visual input processing, particularly that of the motion and peripheral visual cues which are involved in the control of body equilibrium during locomotion.
Ungulates visually and olfactorily discriminating between vegetation patches in grasslands often encounter restriction of target visibility due to light intensity changes; however, little is known ...about their performance in such a context. We developed and tested an apparatus for evaluating the visual and olfactory discrimination ability of cattle under controlled target visibility, focusing on the discrimination at a short distance. The apparatus was designed to contain a discrimination target under a sliding cover of variable light transmission levels and behind a vent of a fixed size and aperture so as to control the visibility of the target (14–100% restrictions) while ensuring a constant level of odor. Twelve Japanese Black cows were allowed to choose between two apparatuses presenting a pair of targets: green forage versus empty, green forage versus dead forage, or green forage versus green–dead mixture. Cows rapidly learned to slide open the cover to reach the selected target, consistently chose the green forage against the alternative except against the green–dead mixture under 100% visual restriction, and remembered the reaching procedure for at least 16 days. The results indicate the usefulness of the apparatus for assessing close visual and olfactory discrimination ability of cattle in detail.
●Designed to simulate close investigation of targets at varying light intensities.●Can control the visibility of targets while ensuring a constant level of odor.●First to control target visibility by manipulating light intensity.●Useful for assessing visual and olfactory discrimination ability of cattle.
•Visual restriction alter gait parameters in young healthy adults.•Participants improve gait parameters when using haptic information delivered by fixed or mobile supports.•Haptic information is ...functional when delivered laterally.•Haptic information does not fully compensate visual restriction.
We investigated the effects of lightly touching fixed and mobile supports on gait parameters and center of mass oscillations in visually restricted young adults. Fourteen healthy male and female adults of mean=23.6 years (SD=1.6 years). Twelve walking conditions were completed on the GAITRite measurement system, resulting from crossing 3 conditions of visual restriction (no restriction, partial restriction, blindfolded) and 4 conditions of haptic supplementation (no supplementation, with a cane used as “light touch”, with a cane sliding on the ground, while touching a soft elastic handrail). Gait speed, stance time, step length and the basis of support were measured. Accelerations of center of mass were also recorded through an accelerometer and the displacements of center of mass were analyzed. Results showed that visual restriction decreased in gait speed, reduced step length, while it increased the base of support and the amplitude of CoM displacements. In the full restriction condition, haptic supplementation provided by the use of the classic cane improved normalized stance time (%). In addition, in the no vision condition, both the classic cane and the soft handrail increased step length and reduced medio-lateral oscillations of the CoM. These results suggest that in visually restricted healthy adults, lightly touching a fixed (soft handrail) or a mobile (classic cane) support contributes to adaptation of gait parameters and postural control during locomotion.
In a normal Voronoi diagram, each site is able to see all the points in the plane. In this paper, we study the case such that each site is only able to see a visually restricted region in the plane ...and construct the so-called Visual Restriction Voronoi Diagram (VRVD). We show that the visual restriction Voronoi cell of each site is not necessarily convex and it could consist of many disjoint regions. We prove that the combinatorial complexity of the VRVD on n sites is Θ(n2), and then show that the VRVD can be constructed in O(n2) time and O(n2) space. Besides that, we also give another algorithm with an extra logn factor of running time to compute VRVD, which is easy to implement in practice.
•Fitts’ law holds for pointing of young and old under conditions of visual restriction.•The elderly obtain the same level accuracy as the young by sacrificing movement time.•The elderly made a very ...similar use of the available sensory information as the young.•Information of hand movement is more useful for both two ages than target location.
The goal of this study was to investigate the effects of aging on pointing movements under restricted visual feedback of hand movement and target location. Fifteen young subjects and fifteen elderly subjects performed pointing movements under four restricted visual feedback conditions that included full visual feedback of hand movement and target location (FV), no visual feedback of hand movement and target location condition (NV), no visual feedback of hand movement (NM) and no visual feedback of target location (NT). This study suggested that Fitts’ law applied for pointing movements of the elderly adults under different visual restriction conditions. Moreover, significant main effect of aging on movement times has been found in all four tasks. The peripheral and central changes may be the key factors for these different characteristics. Furthermore, no significant main effects of age on the mean accuracy rate under condition of restricted visual feedback were found. The present study suggested that the elderly subjects made a very similar use of the available sensory information as young subjects under restricted visual feedback conditions. In addition, during the pointing movement, information about the hand’s movement was more useful than information about the target location for young and elderly subjects.
Fitts’ law robustly predicts the time required to move rapidly to a target. However, it is unclear whether Fitts’ law holds for visually guided actions under visually restricted conditions. We tested ...whether Fitts’ law applies under various conditions of visual restriction and compared pointing movements in each condition. Ten healthy participants performed four pointing movement tasks under different visual feedback conditions, including full-vision (FV), no-hand-movement (NM), no-target-location (NT), and no-vision (NV) feedback conditions. The movement times (MTs) for each task exhibited highly linear relationships with the index of difficulty (r2>.96). These findings suggest that pointing movements follow Fitts’ law even when visual feedback is restricted or absent. However, the MTs and accuracy of pointing movements decreased for difficult tasks involving visual restriction.
This paper reports the field test of a visual restriction treatment for a rural intersection with a high rate of injury crashes. A human factors analysis of the asymmetric pattern of crashes at the ...site suggested that most of the crashes were the result of anticipatory decision-making occasioned by visual characteristics of the eastbound approach to the intersection. The field test examined the effectiveness of a visual restriction treatment directed at eliminating drivers’ anticipatory decision-making. The treatment consisted of a hessian screen erected along the eastbound approach to the intersection beginning 125
m prior to intersection and ending 25
m prior to intersection. Over 2 days of testing, approximately 300 drivers’ reactions at the intersection were observed and their responses to a brief survey recorded. The test indicated a 23% reduction in the 80th percentile and mean approach speeds and elimination of all approach speeds over 57
km/h following introduction of the treatment. Survey results showed that the treatment was visually acceptable to the majority of drivers using the intersection and did not affect its perceived safety. Follow-on analyses compared speed data before the treatment, and 2, 21, and 37 weeks after installation of the treatment. These analyses showed that approach speeds remained low; 30% lower than pre-treatment speeds for both the 80th percentile and the average approach speeds. Of perhaps the greatest significance, no crash resulting in serious injury or death has occurred at the intersection since installation of the treatment to the present time.
The operation of the touch screen is a typical pointing movement. Because touch screens has such a wide range of applications, the users of touch screen will necessarily include people of all age ...groups. The variation in physical and psychomotor capability between different age groups which affect touch screen performance should, therefore, be studied to facilitate the design of touch screen user interface is necessary. The goal of the study was to examine the effect of aging on pointing movements under restricted visual feedback conditions (i.e., full-vision, no feedback about hand movement, no feedback about target location, and no visual feedback of any type). In light of the fact that different age groups exhibit different kinds of movement behaviour patterns, suggestions for the design of touch screen user interface were outlined.
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