The Experts below are selected from a list of 1620 Experts worldwide ranked by ideXlab platform
Oleg V Komogortsev - One of the best experts on this subject based on the ideXlab platform.
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complex Eye movement pattern biometrics the effects of environment and stimulus
IEEE Transactions on Information Forensics and Security, 2013Co-Authors: Corey D Holland, Oleg V KomogortsevAbstract:This paper presents an objective evaluation of the effects of Eye Tracking specification and stimulus presentation on the biometric viability of complex Eye movement patterns. Six spatial accuracy tiers (0.5°, 1.0°, 1.5°, 2.0°, 2.5°, 3.0°), six temporal resolution tiers (1000, 500, 250, 120, 75, 30 Hz), and five stimulus types (simple, complex, cognitive, textual, random) are evaluated to identify acceptable conditions under which to collect Eye movement data. The results suggest the use of Eye Tracking Equipment capable of at least 0.5° spatial accuracy and 250 Hz temporal resolution for biometric purposes, whereas stimulus had little effect on the biometric viability of Eye movements.
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complex Eye movement pattern biometrics analyzing fixations and saccades
International Conference on Biometrics, 2013Co-Authors: Corey D Holland, Oleg V KomogortsevAbstract:This paper presents an objective evaluation of previously unexplored biometric techniques utilizing patterns identifiable in human Eye movements to distinguish individuals. The distribution of primitive Eye movement features are compared between Eye movement recordings using algorithms based on the following statistical tests: the Ansari-Bradley test, the Mann-Whitney U-test, the two-sample Kolmogorov-Smirnov test, the two-sample t-test, and the two-sample Cramer-von Mises test. Score-level information fusion is applied and evaluated by: weighted mean, support vector machine, random forest, and likelihood ratio. The accuracy of each comparison/jusion algorithm is evaluated, with results suggesting that, on high resolution Eye Tracking Equipment, it is possible to obtain equal error rates of 16.5% and rank-1 identification rates of 82.6% using the two-sample Cramer-von Mises test and score-level information fusion by random forest, the highest accuracy results on the considered dataset.
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biometric verification via complex Eye movements the effects of environment and stimulus
International Conference on Biometrics: Theory Applications and Systems, 2012Co-Authors: Corey D Holland, Oleg V KomogortsevAbstract:This paper presents an objective evaluation of the effects of stimulus type and Eye Tracking specifications on the accuracy of biometric verification based on complex Eye movement patterns (CEM). Five stimulus types (simple, complex, cognitive, random, textual), six spatial accuracy tiers (0.5°, 1.0°, 1.5°, 2.0°, 2.5°, 3.0°), and six temporal resolution tiers (1000 Hz, 500 Hz, 250 Hz, 120 Hz, 75 Hz, 30 Hz) are evaluated to identify their effects. The results suggest the use of Eye Tracking Equipment capable of 0.5° spatial accuracy and 250 Hz temporal resolution for biometric purposes, though biometric accuracy remains achievable for systems capable of at least 1.0° spatial accuracy and 30 Hz temporal resolution. While not conclusive, the complex and textual pattern stimuli provided the greatest accuracy, with little difference between the remaining stimuli.
Corey D Holland - One of the best experts on this subject based on the ideXlab platform.
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complex Eye movement pattern biometrics the effects of environment and stimulus
IEEE Transactions on Information Forensics and Security, 2013Co-Authors: Corey D Holland, Oleg V KomogortsevAbstract:This paper presents an objective evaluation of the effects of Eye Tracking specification and stimulus presentation on the biometric viability of complex Eye movement patterns. Six spatial accuracy tiers (0.5°, 1.0°, 1.5°, 2.0°, 2.5°, 3.0°), six temporal resolution tiers (1000, 500, 250, 120, 75, 30 Hz), and five stimulus types (simple, complex, cognitive, textual, random) are evaluated to identify acceptable conditions under which to collect Eye movement data. The results suggest the use of Eye Tracking Equipment capable of at least 0.5° spatial accuracy and 250 Hz temporal resolution for biometric purposes, whereas stimulus had little effect on the biometric viability of Eye movements.
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complex Eye movement pattern biometrics analyzing fixations and saccades
International Conference on Biometrics, 2013Co-Authors: Corey D Holland, Oleg V KomogortsevAbstract:This paper presents an objective evaluation of previously unexplored biometric techniques utilizing patterns identifiable in human Eye movements to distinguish individuals. The distribution of primitive Eye movement features are compared between Eye movement recordings using algorithms based on the following statistical tests: the Ansari-Bradley test, the Mann-Whitney U-test, the two-sample Kolmogorov-Smirnov test, the two-sample t-test, and the two-sample Cramer-von Mises test. Score-level information fusion is applied and evaluated by: weighted mean, support vector machine, random forest, and likelihood ratio. The accuracy of each comparison/jusion algorithm is evaluated, with results suggesting that, on high resolution Eye Tracking Equipment, it is possible to obtain equal error rates of 16.5% and rank-1 identification rates of 82.6% using the two-sample Cramer-von Mises test and score-level information fusion by random forest, the highest accuracy results on the considered dataset.
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biometric verification via complex Eye movements the effects of environment and stimulus
International Conference on Biometrics: Theory Applications and Systems, 2012Co-Authors: Corey D Holland, Oleg V KomogortsevAbstract:This paper presents an objective evaluation of the effects of stimulus type and Eye Tracking specifications on the accuracy of biometric verification based on complex Eye movement patterns (CEM). Five stimulus types (simple, complex, cognitive, random, textual), six spatial accuracy tiers (0.5°, 1.0°, 1.5°, 2.0°, 2.5°, 3.0°), and six temporal resolution tiers (1000 Hz, 500 Hz, 250 Hz, 120 Hz, 75 Hz, 30 Hz) are evaluated to identify their effects. The results suggest the use of Eye Tracking Equipment capable of 0.5° spatial accuracy and 250 Hz temporal resolution for biometric purposes, though biometric accuracy remains achievable for systems capable of at least 1.0° spatial accuracy and 30 Hz temporal resolution. While not conclusive, the complex and textual pattern stimuli provided the greatest accuracy, with little difference between the remaining stimuli.
Thomas, Neil M - One of the best experts on this subject based on the ideXlab platform.
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Children With Developmental Coordination Disorder Show Altered Visuomotor Control During Stair Negotiation Associated With Heightened State Anxiety
'Frontiers Media SA', 2020Co-Authors: Johnny Vv Parr, Foster, Richard J, Wood Greg, Thomas, Neil M, Hollands, Mark AAbstract:Safe stair negotiation is an everyday task that children with developmental coordination disorder (DCD) are commonly thought to struggle with. Yet, there is currently a paucity of research supporting these claims. We investigated the visuomotor control strategies underpinning stair negotiation in children with (N = 18, age = 10.50 ± 2.04 years) and without (N = 16, age = 10.94 ± 2.08 years) DCD by measuring kinematics, gaze behavior and state anxiety as they ascended and descended a staircase. A questionnaire was administered to determine parents’ confidence in their child’s ability to safely navigate stairs and their child’s fall history (within the last year). Kinematics were measured using three-dimensional motion capture (Vicon), whilst gaze was measured using mobile Eye-Tracking Equipment (Pupil labs). The parents of DCD children reported significantly lower confidence in their child’s ability to maintain balance on the stairs and significantly more stair-related falls in the previous year compared to the parents of typically developing (TD) children. During both stair ascent and stair descent, the children with DCD took longer to ascend/descend the staircase and displayed greater handrail use, reflecting a more cautious stair negotiation strategy. No differences were observed between groups in their margin of stability, but the DCD children exhibited significantly greater variability in their foot-clearances over the step edge, which may increase the risk of a fall. For stair descent only, the DCD children reported significantly higher levels of state anxiety than the TD children and looked significantly further along the staircase during the initial entry phase, suggesting an anxiety-related response that may bias gaze toward the planning of future stepping actions over the accurate execution of an ongoing step. Taken together, our findings provide the first quantifiable evidence that (a) safe stair negotiation is a significant challenge for children with DCD, and that (b) this challenge is reflected by marked differences in their visuomotor control strategies and state anxiety levels. Whilst it is currently unclear whether these differences are contributing to the frequency of stair-related falls in children with DCD, our findings pave the way for future research to answer these important questions
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Visually fixating or Tracking another person decreases balance control in young and older females walking in a real-world scenario
'Elsevier BV', 2018Co-Authors: Thomas, Neil M, Dewhurst Susan, Donovan Tim, Bampouras TheodorosAbstract:Balance control during overground walking was assessed in 10 young (23.6 ± 3.4) and 10 older (71.0 ± 5.5 years) healthy females during free gaze, and when fixating or Tracking another person in an everyday use waiting room. Balance control was characterised by medial/lateral sacrum acceleration dispersion, and gaze fixations were simultaneously assessed with Eye Tracking Equipment. The results showed decreased balance control when fixating a stationary (p=0.003, gav=0.19) and Tracking a walking (p=0.027, gav=0.16) person compared to free gaze. The older adults exhibited reduced baseline stability throughout, but the decrease caused by the visual tasks were not more profound than the younger adults. The decreased balance control when fixating on or Tracking the observed person was likely due to more challenging conditions for interpreting retinal flow, which facilitated less reliable estimates of self-motion through vision. The older adults may also have adopted a more rigid posture to facilitate visual stability, which attenuated any ageing effect of the visual tasks. The decrease in balance control, the first to be shown in this context, may warrant further investigation in those with ocular or vestibular dysfunction
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Visually fixating or Tracking another person decreases balance control in young and older females walking in a real-world scenario
'Elsevier BV', 2018Co-Authors: Thomas, Neil M, Dewhurst Susan, Donovan Tim, Bampouras, Theodoros M.Abstract:Balance control during overground walking was assessed in 10 young (23.6 ± 3.4) and 10 older (71.0 ± 5.5 years) healthy females during free gaze, and when fixating or Tracking another person in an everyday use waiting room. Balance control was characterised by medial/lateral sacrum acceleration dispersion, and gaze fixations were simultaneously assessed with Eye Tracking Equipment. The results showed decreased balance control when fixating a stationary (p = 0.003, gav = 0.19) and Tracking a walking (p = 0.027, gav = 0.16) person compared to free gaze. The older adults exhibited reduced baseline stability throughout, but the decrease caused by the visual tasks was not more profound than the younger adults. The decreased balance control when fixating on or Tracking the observed person was likely due to more challenging conditions for interpreting retinal flow, which facilitated less reliable estimates of self-motion through vision. The older adults either processed retinal flow during the tasks as effectively as the young adults, or they adopted a more rigid posture to facilitate visual stability, which masked any ageing effect of the visual tasks. The decrease in balance control, the first to be shown in this context, may warrant further investigation in those with ocular or vestibular dysfunction
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Smooth pursuits decrease balance control during locomotion in young and older healthy females
'Springer Science and Business Media LLC', 2017Co-Authors: Thomas, Neil M, Dewhurst Susan, Bampouras Theodoros, Donovan Tim, Macaluso Andrea, Vannozzi GiuseppeAbstract:Dynamic balance control - characterised as movement of the trunk and lower limbs - was assessed during fixation of a fixed target, smooth pursuits and saccadic Eye movements in ten young (22.9 ± 1.5 years) and ten older (72.1 ± 8.2 years) healthy females walking overground. Participants were presented with visual stimuli to initiate Eye movements, and posture and gaze were assessed with motion analysis and Eye Tracking Equipment. The results showed an increase in medial/lateral (ML) trunk movement (C7: p = 0.012; sacrum: p = 0.009) and step-width variability (p = 0.052) during smooth pursuits compared to a fixed target, with no changes for saccades compared to a fixed target. The elders demonstrated greater ML trunk movement (sacrum: p = 0.037) and step-width variability (p = 0.037) than the younger adults throughout, although this did not interact with the Eye movements. The findings showed that smooth pursuits decreased balance control in young and older adults similarly, which was likely a consequence of more complicated retinal flow. Since healthy elders are typically already at a postural disadvantage, further decreases in balance caused by smooth pursuits are undesirable
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Eye Movements Affect Postural Control in Young and Older Females
'Frontiers Media SA', 2016Co-Authors: Thomas, Neil M, Donovan Tim, Bampouras, Theodoros M., Dewhurst SusanAbstract:Visual information is used for postural stabilization in humans. However, little is known about how Eye movements prevalent in everyday life interact with the postural control system in older individuals. Therefore, the present study assessed the effects of stationary gaze fixations, smooth pursuits, and saccadic Eye movements, with combinations of absent, fixed and oscillating large-field visual backgrounds to generate different forms of retinal flow, on postural control in healthy young and older females. Participants were presented with computer generated visual stimuli, whilst postural sway and gaze fixations were simultaneously assessed with a force platform and Eye Tracking Equipment, respectively. The results showed that fixed backgrounds and stationary gaze fixations attenuated postural sway. In contrast, oscillating backgrounds and smooth pursuits increased postural sway. There were no differences regarding saccades. There were also no differences in postural sway or gaze errors between age groups in any visual condition. The stabilizing effect of the fixed visual stimuli show how retinal flow and extraocular factors guide postural adjustments. The destabilizing effect of oscillating visual backgrounds and smooth pursuits may be related to more challenging conditions for determining body shifts from retinal flow, and more complex extraocular signals, respectively. Because the older participants matched the young group's performance in all conditions, decreases of posture and gaze control during stance may not be a direct consequence of healthy aging. Further research examining extraocular and retinal mechanisms of balance control and the effects of Eye movements, during locomotion, is needed to better inform fall prevention interventions
Wood Greg - One of the best experts on this subject based on the ideXlab platform.
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Children With Developmental Coordination Disorder Exhibit Greater Stepping Error Despite Similar Gaze Patterns and State Anxiety Levels to Their Typically Developing Peers
'Frontiers Media SA', 2020Co-Authors: Johnny Vv Parr, Foster, Richard J, Wood Greg, Hollands, Mark AAbstract:This study examined stepping accuracy, gaze behavior, and state-anxiety in children with (N = 21, age M = 10.81, SD = 1.89) and without (N = 18, age M = 11.39, SD = 2.06) developmental coordination disorder (DCD) during an adaptive locomotion task. Participants walked at a self-selected pace along a pathway, placing their foot into a raised rectangular floor-based target box followed by either no obstacles, one obstacle, or two obstacles. Stepping kinematics and accuracy were determined using three-dimensional motion capture, whilst gaze was determined using mobile Eye-Tracking Equipment. The children with DCD displayed greater foot placement error and variability when placing their foot within the target box and were more likely to make contact with its edges than their typically developing (TD) peers. The DCD group also displayed greater variability in the length and width of their steps in the approach to the target box. No differences were observed between groups in any of the gaze variables measured, in mediolateral velocity of the center of mass during the swing phase into the target box, or in the levels of self-reported state-anxiety experienced prior to facing each task. We therefore provide the first quantifiable evidence that deficits to foot placement accuracy and precision may be partially responsible for the increased incidence of trips and falls in DCD, and that these deficits are likely to occur independently from gaze behavior and state-anxiety
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Children With Developmental Coordination Disorder Show Altered Visuomotor Control During Stair Negotiation Associated With Heightened State Anxiety
'Frontiers Media SA', 2020Co-Authors: Johnny Vv Parr, Foster, Richard J, Wood Greg, Thomas, Neil M, Hollands, Mark AAbstract:Safe stair negotiation is an everyday task that children with developmental coordination disorder (DCD) are commonly thought to struggle with. Yet, there is currently a paucity of research supporting these claims. We investigated the visuomotor control strategies underpinning stair negotiation in children with (N = 18, age = 10.50 ± 2.04 years) and without (N = 16, age = 10.94 ± 2.08 years) DCD by measuring kinematics, gaze behavior and state anxiety as they ascended and descended a staircase. A questionnaire was administered to determine parents’ confidence in their child’s ability to safely navigate stairs and their child’s fall history (within the last year). Kinematics were measured using three-dimensional motion capture (Vicon), whilst gaze was measured using mobile Eye-Tracking Equipment (Pupil labs). The parents of DCD children reported significantly lower confidence in their child’s ability to maintain balance on the stairs and significantly more stair-related falls in the previous year compared to the parents of typically developing (TD) children. During both stair ascent and stair descent, the children with DCD took longer to ascend/descend the staircase and displayed greater handrail use, reflecting a more cautious stair negotiation strategy. No differences were observed between groups in their margin of stability, but the DCD children exhibited significantly greater variability in their foot-clearances over the step edge, which may increase the risk of a fall. For stair descent only, the DCD children reported significantly higher levels of state anxiety than the TD children and looked significantly further along the staircase during the initial entry phase, suggesting an anxiety-related response that may bias gaze toward the planning of future stepping actions over the accurate execution of an ongoing step. Taken together, our findings provide the first quantifiable evidence that (a) safe stair negotiation is a significant challenge for children with DCD, and that (b) this challenge is reflected by marked differences in their visuomotor control strategies and state anxiety levels. Whilst it is currently unclear whether these differences are contributing to the frequency of stair-related falls in children with DCD, our findings pave the way for future research to answer these important questions
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Examining the Spatiotemporal Disruption to Gaze When Using a Myoelectric Prosthetic Hand
'Informa UK Limited', 2017Co-Authors: Parr Johnny, Vine, Samuel J., Harrison Neil, Wood GregAbstract:The aim of this study was to provide a detailed account of the spatial and temporal disruptions to Eye-hand coordination when using a prosthetic hand during a sequential fine motor skill. Twenty-one able-bodied participants performed 15 trials of the picking up coins task derived from the Southampton Hand Assessment Procedure with their anatomic hand and with a prosthesis simulator while wearing Eye-Tracking Equipment. Gaze behavior results revealed that when using the prosthesis, performance detriments were accompanied by significantly greater hand-focused gaze and a significantly longer time to disengage gaze from manipulations to plan upcoming movements. The study findings highlight key metrics that distinguish disruptions to Eye-hand coordination that may have implications for the training of prosthesis use
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Examining the spatiotemporal disruption to gaze when using a myoelectric prosthetic hand
'Informa UK Limited', 2017Co-Authors: Parr Jvv, Sj Vine, Nr Harrison, Wood GregAbstract:The aim of this study was to provide a detailed account of the spatial and temporal disruptions to Eye-hand coordination when using a prosthetic hand during a sequential fine motor skill. Twenty-one abled-bodied participants performed 15 trials of the ‘picking up coins’ task derived from the Southampton Hand Assessment Procedure (SHAP) with their anatomic hand and with a prosthesis simulator while wearing Eye-Tracking Equipment. Gaze behaviour results revealed that when using the prosthesis, performance detriments were accompanied by significantly greater hand-focused gaze and a significantly longer time to disengage gaze from manipulations to plan upcoming movements. Our findings highlight key metrics that distinguish disruptions to Eye-hand coordination that might have implications for the training of prosthesis use
Dewhurst Susan - One of the best experts on this subject based on the ideXlab platform.
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Visually fixating or Tracking another person decreases balance control in young and older females walking in a real-world scenario
'Elsevier BV', 2018Co-Authors: Thomas, Neil M, Dewhurst Susan, Donovan Tim, Bampouras, Theodoros M.Abstract:Balance control during overground walking was assessed in 10 young (23.6 ± 3.4) and 10 older (71.0 ± 5.5 years) healthy females during free gaze, and when fixating or Tracking another person in an everyday use waiting room. Balance control was characterised by medial/lateral sacrum acceleration dispersion, and gaze fixations were simultaneously assessed with Eye Tracking Equipment. The results showed decreased balance control when fixating a stationary (p = 0.003, gav = 0.19) and Tracking a walking (p = 0.027, gav = 0.16) person compared to free gaze. The older adults exhibited reduced baseline stability throughout, but the decrease caused by the visual tasks was not more profound than the younger adults. The decreased balance control when fixating on or Tracking the observed person was likely due to more challenging conditions for interpreting retinal flow, which facilitated less reliable estimates of self-motion through vision. The older adults either processed retinal flow during the tasks as effectively as the young adults, or they adopted a more rigid posture to facilitate visual stability, which masked any ageing effect of the visual tasks. The decrease in balance control, the first to be shown in this context, may warrant further investigation in those with ocular or vestibular dysfunction
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Visually fixating or Tracking another person decreases balance control in young and older females walking in a real-world scenario
'Elsevier BV', 2018Co-Authors: Thomas, Neil M, Dewhurst Susan, Donovan Tim, Bampouras TheodorosAbstract:Balance control during overground walking was assessed in 10 young (23.6 ± 3.4) and 10 older (71.0 ± 5.5 years) healthy females during free gaze, and when fixating or Tracking another person in an everyday use waiting room. Balance control was characterised by medial/lateral sacrum acceleration dispersion, and gaze fixations were simultaneously assessed with Eye Tracking Equipment. The results showed decreased balance control when fixating a stationary (p=0.003, gav=0.19) and Tracking a walking (p=0.027, gav=0.16) person compared to free gaze. The older adults exhibited reduced baseline stability throughout, but the decrease caused by the visual tasks were not more profound than the younger adults. The decreased balance control when fixating on or Tracking the observed person was likely due to more challenging conditions for interpreting retinal flow, which facilitated less reliable estimates of self-motion through vision. The older adults may also have adopted a more rigid posture to facilitate visual stability, which attenuated any ageing effect of the visual tasks. The decrease in balance control, the first to be shown in this context, may warrant further investigation in those with ocular or vestibular dysfunction
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Smooth pursuits decrease balance control during locomotion in young and older healthy females
'Springer Science and Business Media LLC', 2017Co-Authors: Thomas, Neil M, Dewhurst Susan, Bampouras Theodoros, Donovan Tim, Macaluso Andrea, Vannozzi GiuseppeAbstract:Dynamic balance control - characterised as movement of the trunk and lower limbs - was assessed during fixation of a fixed target, smooth pursuits and saccadic Eye movements in ten young (22.9 ± 1.5 years) and ten older (72.1 ± 8.2 years) healthy females walking overground. Participants were presented with visual stimuli to initiate Eye movements, and posture and gaze were assessed with motion analysis and Eye Tracking Equipment. The results showed an increase in medial/lateral (ML) trunk movement (C7: p = 0.012; sacrum: p = 0.009) and step-width variability (p = 0.052) during smooth pursuits compared to a fixed target, with no changes for saccades compared to a fixed target. The elders demonstrated greater ML trunk movement (sacrum: p = 0.037) and step-width variability (p = 0.037) than the younger adults throughout, although this did not interact with the Eye movements. The findings showed that smooth pursuits decreased balance control in young and older adults similarly, which was likely a consequence of more complicated retinal flow. Since healthy elders are typically already at a postural disadvantage, further decreases in balance caused by smooth pursuits are undesirable
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Eye Movements Affect Postural Control in Young and Older Females
'Frontiers Media SA', 2016Co-Authors: Thomas, Neil M, Donovan Tim, Bampouras, Theodoros M., Dewhurst SusanAbstract:Visual information is used for postural stabilization in humans. However, little is known about how Eye movements prevalent in everyday life interact with the postural control system in older individuals. Therefore, the present study assessed the effects of stationary gaze fixations, smooth pursuits, and saccadic Eye movements, with combinations of absent, fixed and oscillating large-field visual backgrounds to generate different forms of retinal flow, on postural control in healthy young and older females. Participants were presented with computer generated visual stimuli, whilst postural sway and gaze fixations were simultaneously assessed with a force platform and Eye Tracking Equipment, respectively. The results showed that fixed backgrounds and stationary gaze fixations attenuated postural sway. In contrast, oscillating backgrounds and smooth pursuits increased postural sway. There were no differences regarding saccades. There were also no differences in postural sway or gaze errors between age groups in any visual condition. The stabilizing effect of the fixed visual stimuli show how retinal flow and extraocular factors guide postural adjustments. The destabilizing effect of oscillating visual backgrounds and smooth pursuits may be related to more challenging conditions for determining body shifts from retinal flow, and more complex extraocular signals, respectively. Because the older participants matched the young group's performance in all conditions, decreases of posture and gaze control during stance may not be a direct consequence of healthy aging. Further research examining extraocular and retinal mechanisms of balance control and the effects of Eye movements, during locomotion, is needed to better inform fall prevention interventions
