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Background: Motion sensitivity, or motion sickness, is common in modern vehicular and visually stimulating environments. Several studies have shown a relationship between motion sensitivity and decreased postural stability. We aimed to evaluate the effects of head motion (horizontal and vertical) on postural stability in healthy adults with and without chronic motion sensitivity (CMS). Methods: Sixty healthy adult men and women (age, 20–40 years) with CMS (CMS group, n = 30) and without CMS (non-CMS group, n = 30) participated in the study. Postural stability was assessed during three conditions (static, horizontal head motion, and vertical head motion) using computerized dynamic posturography. Group and condition-related differences in equilibrium scores were evaluated. Results: There was no significant group x condition interaction (F2,114 = 0.9, partial ƞ2 = 0.04, p = 0.35). However, significant condition-related differences in equilibrium scores were observed (F2,114 = 26.4, partial ƞ2 = 0.31, p < 0.001). Equilibrium scores were significantly worse in the horizontal and vertical head motion conditions compared to those in the static condition (p < 0.001), but were comparable in vertical and horizontal head motion conditions (p = 0.27). Conclusions: Postural stability was lower in the horizontal and vertical conditions compared to the static condition. However, horizontal and vertical head motions had comparable effects on postural stability in both CMS and non- CMS groups, contrary to our expectations.

In between attacks, people with migraine report experiencing both visual discomfort and visual illusions induced by stationary high contrast striped patterns. Since both visual illusion and discomfort have been assessed through largely qualitative self-report, it is unclear how their mechanisms might be related with each other. This thesis aimed to investigate whether subjective reports of visual discomfort in people with migraine are associated with the strength of a motion illusion outside attacks. To determine the stimulus for motion illusion strength to be quantified, Experiment 1 measured the physical motion speeds that cancelled the illusory motion effect of five variants of the Fraser-Wilcox illusion in people who do not experience headache. The stimulus type that produced the most robust illusory motion was chosen for subsequent experiments. Experiment 2 compared the motion illusion strength between people with migraine with aura, people with migraine without aura, and non-headache control participants. The relationship between motion illusion strength and self-reported frequency of experiencing visual discomfort in daily life was also investigated. The results indicated that subjective visual discomfort was elevated in people with migraine with aura but that visual discomfort was not accompanied by greater motion illusion strength. These findings suggest that susceptibility to daily visual discomfort is not related to perceived speed of the motion illusion. Experiment 3 investigated whether motion illusion strength is associated with contrast discrimination threshold and motion sensitivity regardless of migraine status. The results revealed that people with better contrast discrimination, but not motion sensitivity, tended to perceive faster motion illusions. The findings of this thesis verify previous self-reports of increased visual discomfort in people with migraine. The experiments, however, do not support that this self-reported experience is derived f

Purpose To explore differences in driving performance of older adults with age-related macular degeneration (AMD) and age-matched controls, and to identify the visual determinants of driving performance in this population. Methods Participants included 33 older drivers with AMD (mean age [M] = 76.6 ± 6.1 years; better eye Age-Related Eye Disease Study grades: early [61%] and intermediate [39%]) and 50 age-matched controls (M = 74.6 ± 5.0 years). Visual tests included visual acuity, contrast sensitivity, visual fields, and motion sensitivity. On-road driving performance was assessed in a dual-brake vehicle by an occupational therapist (masked to drivers' visual status). Outcome measures included driving safety ratings (scale of 1–10, where higher values represented safer driving), types of driving behavior errors, locations at which errors were made, and number of critical errors (CE) requiring an instructor intervention. Results Drivers with AMD were rated as less safe than controls (4.8 vs. 6.2; P = 0.012); safety ratings were associated with AMD severity (early: 5.5 versus intermediate: 3.7), even after adjusting for age. Drivers with AMD had higher CE rates than controls (1.42 vs. 0.36, respectively; rate ratio 3.05, 95% confidence interval 1.47–6.36, P = 0.003) and exhibited more observation, lane keeping, and gap selection errors and made more errors at traffic light–controlled intersections (P < 0.05). Only motion sensitivity was significantly associated with driving safety in the AMD drivers (P = 0.005). Conclusions Drivers with early and intermediate AMD can exhibit impairments in their driving performance, particularly during complex driving situations; motion sensitivity was most strongly associated with driving performance. These findings have important implications for assessing the driving ability of older drivers with visual impairment.

For many older adults, night driving is difficult due to age-related changes affecting vision under low light and glare conditions. However, there is a lack of evidence for healthcare practitioners to base their advice to patients about visual fitness to drive safely at night. This research investigated the relationships between self-reported vision-related night driving difficulties, visual function tests and night driving performance. It was found that vision tests conducted under lower light levels, similar to the night driving environment, were important for predicting poorer night driving performance and for assessing drivers reporting high levels of vision-related night driving difficulties.

Human figures have been animated using a variety of geometric models including stick figures polygonal models and NURBS-based models with muscles flexible skin or clothing. This paper reports on experimental results indicating that a viewer's perception of motion characteristics is affected by the geometric model used for rendering. Subjects were shown a series of paired motion sequences and asked if the two motions in each pair were the same or differentJhe motion sequences in each pair were rendered using the same geometric model. For the three types of motion variation tested sensitivity scores indicate that subjects were better able to observe changes with the polygonal model than they were with the stick figure model. ©1998 IEEE.

Human figures have been animated using a variety of geometric models including stick figures polygonal models and NURBS-based models with muscles flexible skin or clothing. This paper reports on experimental results indicating that a viewer's perception of motion characteristics is affected by the geometric model used for rendering. Subjects were shown a series of paired motion sequences and asked if the two motions in each pair were the same or differentJhe motion sequences in each pair were rendered using the same geometric model. For the three types of motion variation tested sensitivity scores indicate that subjects were better able to observe changes with the polygonal model than they were with the stick figure model. ©1998 IEEE.

Human figures have been animated using a wide variety of geometric models including stick figures, polygonal models, and NURBS-based models with muscles, flexible skin, or clothing. This paper reports on experiments designed to ascertain whether a viewer's perception of motion characteristics is affected by the geometric model used for rendering. Subjects were shown a series of paired motion sequences and asked if the two motions in each pair were `the same' or `different.' The two motion sequences in each pair used the same geometric model. For each trial, the pairs of motion sequences were grouped into two sets where one set was rendered with a stick figure model and the other set was rendered with a polygonal model. Sensitivity measures for each trial indicate that for these sequences subjects were better able to discriminate motion variations with the polygonal model than with the stick figure model.

Human figures have been animated using a wide variety of geometric models including stick figures, polygonal models, and NURBS-based models with muscles, flexible skin, or clothing. This paper reports on experiments designed to ascertain whether a viewer's perception of motion characteristics is affected by the geometric model used for rendering. Subjects were shown a series of paired motion sequences and asked if the two motions in each pair were `the same' or `different.' The two motion sequences in each pair used the same geometric model. For each trial, the pairs of motion sequences were grouped into two sets where one set was rendered with a stick figure model and the other set was rendered with a polygonal model. Sensitivity measures for each trial indicate that for these sequences subjects were better able to discriminate motion variations with the polygonal model than with the stick figure model.