scholarly journals Effects of visual blur on microsaccades during visual exploration

2019 ◽  
Vol 12 (6) ◽  
Author(s):  
Sherry Tang ◽  
Peggy Skelly ◽  
Jorge Otero-Millan ◽  
Jonathan Jacobs ◽  
Jordan Murray ◽  
...  
Keyword(s):  
Visual Search ◽  
Refractive Error ◽  
Reaction Times ◽  
Sampling Strategy ◽  
Visual Exploration ◽  
Optimal Sampling ◽  
Scene Viewing ◽  
Gaze Holding ◽  
The Difference ◽  
Uncorrected Refractive Error

Microsaccades shift the image on the fovea and counteract visual fading. They also serve as an optimal sampling strategy while viewing complex visual scenes. Microsaccade production relies on the amount of retinal error or acuity demand of a visual task. The goal of this study was to assess the effects of blur induced by uncorrected refractive error on visual search. Eye movements were recorded in fourteen healthy subjects with uncorrected and corrected refractive error while they performed a) visual fixation b) blank-scene viewing c) visual search (spot the difference) tasks. Microsaccades, saccades, correctly identified differences and reaction times were analyzed. The frequency of microsaccades and correctly identified differences were lower in the uncorrected refractive error during visual search. No similar change in microsaccades was seen during blank-scene viewing and gaze holding tasks. These findings suggest that visual blur, hence the precision of an image on the fovea, has an important role in calibrating the amplitude of microsaccades during visual scanning.

Effect of Bilingualism on Multitasking: A Pilot Study

2015 ◽  
Vol 22 (3) ◽  
pp. 94-101 ◽  
Author(s):  
Li Hsieh
Keyword(s):  
Executive Control ◽  
Positive Impact ◽  
Reaction Times ◽  
Language Experience ◽  
Bilingual Advantage ◽  
Bilingual Speakers ◽  
Proficiency Level ◽  
Linguistic Representations ◽  
A Cell ◽  
The Difference

Bilingual speakers rely on attentional and executive control to continuously inhibit or activate linguistic representations of competing languages, which leads to an increased efficiency known as “bilingual advantage”. Both monolingual and bilingual speakers were asked to perform multiple tasks of talking on a cell phone while simultaneously attending to simulated driving events. This study examined the effect of bilingualism on participants' performance during a dual-task experiment based on 20 monolingual and 13 bilingual healthy adults. The within-subject and between-subject comparisons were conducted on reaction times of a visual event detection task for (a) only driving and (b) driving while simultaneously engaged in a phone conversation. Results of this study showed that bilingual speakers performed significantly faster than monolingual speakers during the multitasking condition, but not during the driving only condition. Further, bilingual speakers consistently showed a bilingual advantage in reaction times during the multitasking condition, despite varying degrees on a bilingual dominance scale. Overall, experiences in more than one language yield bilingual advantage in better performance than monolingual speakers during a multitasking condition, but not during a single task condition. Regardless of the difference in bilingual proficiency level, such language experience reveals a positive impact on bilingual speakers for multitasking.

scholarly journals Optimal Sampling for the Population Coverage Survey of the New Italian Register Based Census

2021 ◽  
Vol 37 (3) ◽  
pp. 655-671
Author(s):  
Paolo Righi ◽  
Piero Demetrio Falorsi ◽  
Stefano Daddi ◽  
Epifania Fiorello ◽  
Pierpaolo Massoli ◽  
...  
Keyword(s):  
Sampling Design ◽  
Sample Selection ◽  
Sampling Strategy ◽  
Selection Method ◽  
Population Census ◽  
Optimal Sampling ◽  
Population Coverage ◽  
Sample Allocation ◽  
Population Counts ◽  
First Time

Abstract For the first time in 2018 the Italian Institute of Statistics (Istat) implemented the annual Permanent Population Census which relies on the Population Base Register (PBR) and the Population Coverage Survey (PCS). This article provides a general overview of the PCS sampling design, which makes use of the PBR to correct population counts with the extended dual system estimator (Nirel and Glickman 2009). The sample allocation, proven optimal under a set of precision constraints, is based on preliminary estimates of individual probabilities of over-coverage and under-coverage. It defines the expected sample size in terms of individuals, and it oversamples the sub-populations subject to the risk of under/over coverage. Finally, the article introduces a sample selection method, which to the greatest extent possible satisfies the planned allocation of persons in terms of socio-demographic characteristics. Under acceptable assumptions, the article also shows that the sampling strategy enhances the precision of the estimates.

scholarly journals School vision screening programmes in reducing uncorrected refractive error among children in Low and Middle-Income countries-LMIC (systematic review)

2020 ◽  
Vol 10 (4) ◽  
pp. 91-105
Author(s):  
Abraham Opare ◽  
Leila H Abdullahi ◽  
Deon Minnies ◽  
Colin Cook ◽  
Maylene Shung-King ◽  
...  
Keyword(s):  
Academic Performance ◽  
School Children ◽  
Refractive Error ◽  
Positive Impact ◽  
Cost Effective ◽  
Vision Screening ◽  
Middle Income ◽  
Middle Income Countries ◽  
School Vision ◽  
Uncorrected Refractive Error

ackground: The prevalence of uncorrected refractive error among school-age children is on the rise with detrimental effect on academic performance and socio-economic status of those affected. School vision screening programmes appear to be an effective way of identifying children with uncorrected refractive errors so early intervention can be made. Despite the increasing popularity of school vision screening programmes over the past few years, there is a lot of debate on its effectiveness in reducing the proportion of children with uncorrected refractive error in the long term, especially in settings where resources are limited. Some studies argue that school vision screening programmes are effective while other studies have reported otherwise. The purpose of this systematic review was to assess the effectiveness of school vision screening programmes in reducing uncorrected refractive error among children in low and middle income countries using evidence from published studies. Methods and findings: A comprehensive and systematic strategy was used to search various databases including PubMed, Cochrane Central Register of Controlled Trials (CENTRAL) which contains the Cochrane Eyes and vision Trial Register, the Cochrane Library, Medline (1980-2018), CINAHL, Academic Search Premier, Web of Science, the WHO’s Library Information System, Africa-Wide and Scopus. The search was restricted to articles published in English. Randomized control trials, cross-sectional studies, case-control studies and cohort studies were included in this review. Participants included school children with refractive error. Full-text review of search results, data extraction and risk of bias assessment was done by two independent reviewers. The certainty of the evidence was assessed using the GRADE approach and data were pooled using the random-effect model. Thirty studies met the inclusion criteria. This review found moderate certainty evidence indicating that school vision screenings may be effective in reducing uncorrected refractive error among school children by 81% (95% CI: 77%; 84%), 24% (95% CI: 13%; 35%) and 20% (95% CI: 18%; 22%) at two, six, and more than six months respectively after its introduction. Results: Results of this review also suggest that school vision screening may be effective in achieving 54% (95% CI: 25%; 100%), 57% (95% CI: 46%; 70%), 37% (95% CI: 26%; 52%), and 32% (95% CI: 14%; 72%) spectacle-wear compliance among school children at less than three months, at three months, at six months and at more than six months respectively after its introduction (low to moderate certainty evidence). This review further found moderate to high certainty evidence indicating that school vision screening, together with provision of spectacles, may be relatively cost effective, safe and has a positive impact on the academic performance of school children. Conclusion: The findings of this review show that school vision screening, together with provision of spectacles, may be a safe and cost-effective way of reducing the proportion of children with uncorrected refractive error, with long-term positive impact on academic performance of children. Most of the studies included in this review were, however, conducted in Asia. Research to investigate the effectiveness of school vision screening programmes in other parts of the world like Africa where few studies have been conducted is highly recommended

scholarly journals Comparison of organics and heavy metals acute toxicities to Vibrio fischeri

2016 ◽  
Vol 81 (6) ◽  
pp. 697-705 ◽  
Author(s):  
Xuepeng Yang ◽  
Yan Ji ◽  
Fangfang Wang ◽  
Jia Xu ◽  
Xiangzhen Liu ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Cell Death ◽  
Benzoic Acid ◽  
Death Rate ◽  
Vibrio Fischeri ◽  
Reaction Times ◽  
Inhibition Rate ◽  
Cell Death Rate ◽  
Bioluminescence Inhibition ◽  
The Difference

Vibrio fischeri bioluminescence inhibition has been widely used to test acute toxicities of metals and organics contaminants. However, the differences of metals and organics acute toxicities to V. fischeri have not been compared. Here, four heavy metals (Zn2+, Cu2+, Cd2+, Cr6+) and five organics (phenol, benzoic acid, p-hydroxy benzoic acid, nitro-benzene and benzene) acute toxicities to V. fischeri were investigated. Heavy metals toxicities to V. fischeri were increased along with the reaction time, while the organics toxicities kept the same level in different reaction times. In order to explain the difference, the relative cell death rate of V. fischeri was detected. In metals toxicities tests, the bioluminescence inhibition rate of V. fischeri was found to be significantly higher than the relative cell death rate (P<0.05), while for the organics toxicities tests, the cell death rate was similar to the bioluminescence inhibition rate. These results indicated that organics acute toxicities to V. fischeri could reflect the death of cell, but metals acute toxicities to V. fischeri may not lead to the death of cell, just represent the bioluminescence inhibition.

Rapid assessment of avoidable blindness in Papua New Guinea: a nationwide survey

2018 ◽  
Vol 103 (3) ◽  
pp. 338-342 ◽  
Author(s):  
Ling Lee ◽  
Fabrizio D'Esposito ◽  
Jambi Garap ◽  
Geoffrey Wabulembo ◽  
Samuel Peter Koim ◽  
...  
Keyword(s):  
Papua New Guinea ◽  
Refractive Error ◽  
Rapid Assessment ◽  
New Guinea ◽  
Nationwide Survey ◽  
Population Based ◽  
Vision Impairment ◽  
Cross Sectional ◽  
National Capital ◽  
Uncorrected Refractive Error

ObjectiveTo estimate the prevalence and main causes of blindness and vision impairment in people aged 50 years and older in Papua New Guinea (PNG).DesignNational cross-sectional population-based survey in National Capital District (NCD), Highlands, Coastal and Islands regions.MethodsAdults aged 50 years and above were recruited from 100 randomly selected clusters. Each participant underwent monocular presenting and pinhole visual acuity (VA) assessment and lens examination. Those with pinhole VA<6/12 in either eye had a dilated fundus examination to determine the primary cause of reduced vision. Those with obvious lens opacity were interviewed on barriers to cataract surgery.ResultsA total of 4818 adults were examined. The age-adjusted and sex-adjusted prevalence of blindness (VA <3/60), severe vision impairment (SVI, VA <6/60 but ≥3/60), moderate vision impairment (MVI, VA <6/18 but ≥6/60) and early vision impairment (EVI, VA <6/12 but ≥6/18) was 5.6% (95% CI 4.9% to 6.3%), 2.9% (95% CI 2.5% to 3.4%), 10.9% (95% CI 9.9% to 11.9%) and 7.3% (95% CI 6.6% to 8.0%), respectively. The main cause of blindness, SVI and MVI was cataract, while uncorrected refractive error was the main cause of EVI. A significantly higher prevalence of blindness, SVI and MVI occurred in the Highlands compared with NCD. Across all regions, women had lower cataract surgical coverage and spectacle coverage than men.ConclusionsPNG has one of the highest reported prevalence of blindness globally. Cataract and uncorrected refractive error are the main causes, suggesting a need for increased accessible services with improved resources and advocacy for enhancing eye health literacy.

scholarly journals Prevalence and causes of vision loss in North Africa and Middle East in 2015: magnitude, temporal trends and projections

2018 ◽  
Vol 103 (7) ◽  
pp. 863-870 ◽  
Author(s):  
Rim Kahloun ◽  
Moncef Khairallah ◽  
Serge Resnikoff ◽  
Maria Vittoria Cicinelli ◽  
Seth R Flaxman ◽  
...  
Keyword(s):  
Diabetic Retinopathy ◽  
Middle East ◽  
North Africa ◽  
Refractive Error ◽  
Vision Loss ◽  
Corneal Opacity ◽  
Vision Impairment ◽  
Age Related Macular Degeneration ◽  
Age Related ◽  
Uncorrected Refractive Error

BackgroundTo assess the prevalence and causes of vision impairment in North Africa and the Middle East (NAME) from 1990 to 2015 and to forecast projections for 2020.MethodsBased on a systematic review of medical literature, the prevalence of blindness (presenting visual acuity (PVA) <3/60 in the better eye), moderate and severe vision impairment (MSVI; PVA <6/18 but ≥3/60) and mild vision impairment (PVA <6/12 but ≥6/18) was estimated for 2015 and 2020.ResultsThe age-standardised prevalence of blindness and MSVI for all ages and genders decreased from 1990 to 2015, from 1.72 (0.53–3.13) to 0.95% (0.32%–1.71%), and from 6.66 (3.09–10.69) to 4.62% (2.21%–7.33%), respectively, with slightly higher figures for women than men. Cataract was the most common cause of blindness in 1990 and 2015, followed by uncorrected refractive error. Uncorrected refractive error was the leading cause of MSVI in the NAME region in 1990 and 2015, followed by cataract. A reduction in the proportions of blindness and MSVI due to cataract, corneal opacity and trachoma is predicted by 2020. Conversely, an increase in the proportion of blindness attributable to uncorrected refractive error, glaucoma, age-related macular degeneration and diabetic retinopathy is expected.ConclusionsIn 2015 cataract and uncorrected refractive error were the major causes of vision loss in the NAME region. Proportions of vision impairment from cataract, corneal opacity and trachoma are expected to decrease by 2020, and those from uncorrected refractive error, glaucoma, diabetic retinopathy and age-related macular degeneration are predicted to increase by 2020.

Gender Inequality in Global Burden of Uncorrected Refractive Error

2019 ◽  
Vol 198 ◽  
pp. 1-7 ◽  
Author(s):  
Lixia Lou ◽  
Xi Liu ◽  
Xiajing Tang ◽  
Linyan Wang ◽  
Juan Ye
Keyword(s):  
Gender Inequality ◽  
Refractive Error ◽  
Global Burden ◽  
Uncorrected Refractive Error

scholarly journals Implicit Detection Observation in Different Features, Exposure Duration, and Delay During Change Blindness

2021 ◽  
Vol 11 ◽  
Author(s):  
Wang Xiang
Keyword(s):  
Change Detection ◽  
Exposure Duration ◽  
Change Blindness ◽  
Reaction Times ◽  
Set Size ◽  
The Difference ◽  
Detection Effect

To investigate whether implicit detection occurs uniformly during change blindness with single or combination feature stimuli, and whether implicit detection is affected by exposure duration and delay, two one-shot change detection experiments are designed. The implicit detection effect is measured by comparing the reaction times (RTs) of baseline trials, in which stimulus exhibits no change and participants report “same,” and change blindness trials, in which the stimulus exhibits a change but participants report “same.” If the RTs of blindness trials are longer than those of baseline trials, implicit detection has occurred. The strength of the implicit detection effect was measured by the difference in RTs between the baseline and change blindness trials, where the larger the difference, the stronger the implicit detection effect. In both Experiments 1 and 2, the results showed that the RTs of change blindness trials were significantly longer than those of baseline trials. Whether under set size 4, 6, or 8, the RTs of the change blindness trials were significantly longer than those in the baseline trials. In Experiment 1, the difference between the baseline trials’ RTs and change blindness trials’ RTs of the single features was significantly larger than that of the combination features. However, in Experiment 2, the difference between the baseline trials’ RTs and the change blindness trials’ RTs of single features was significantly smaller than that of the combination features. In Experiment 1a, when the exposure duration was shorter, the difference between the baseline and change blindness trials’ RTs was smaller. In Experiment 2, when the delay was longer, the difference between the two trials’ RTs was larger. These results suggest that regardless of whether the change occurs in a single or a combination of features and whether there is a long exposure duration or delay, implicit detection occurs uniformly during the change blindness period. Moreover, longer exposure durations and delays strengthen the implicit detection effect. Set sizes had no significant impact on implicit detection.

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