One of the main tasks of vision is to individuate and recognize specific objects. Unlike the detection of basic features, object individuation is strictly limited in capacity. Previous studies of ...capacity, in terms of subitizing ranges or visual working memory, have emphasized spatial limits in the number of objects that can be apprehended simultaneously. Here, we present psychophysical and electrophysiological evidence that capacity limits depend instead on time. Contrary to what is commonly assumed, subitizing, the reading-out a small set of individual objects, is not an instantaneous process. Instead, individuation capacity increases in steps within the lifetime of visual persistence of the stimulus, suggesting that visual capacity limitations arise as a result of the narrow window of feedforward processing. We characterize this temporal window as coordinating individuation and integration of sensory information over a brief interval of around 100 ms. Neural signatures of integration windows are revealed in reset alpha oscillations shortly after stimulus onset within generators in parietal areas. Our findings suggest that short-lived alpha phase synchronization (≈1 cycle) is key for individuation and integration of visual transients on rapid time scales (<100 ms). Within this time frame intermediate-level vision provides an equilibrium between the competing needs to individuate invariant objects, integrate information about those objects over time, and remain sensitive to dynamic changes in sensory input. We discuss theoretical and practical implications of temporal windows in visual processing, how they create a fundamental capacity limit, and their role in constraining the real-time dynamics of visual processing.
•Association between occlusion time preferences and in-car glance durations was found.•Association is lost if the in-car task is a visual search task.•Ability to use peripheral vision and in-car task ...structure may explain the loss of the association.•Occlusion can be used to control for inter-individual differences in distraction testing.•It is strongly recommended to use driving performance metrics with occlusion measures.
Drivers have spare visual capacity in driving, and often this capacity is used for engaging in secondary in-car tasks. Previous research has suggested that the spare visual capacity could be estimated with the occlusion method. However, the relationship between drivers’ occlusion times and in-car glance duration preferences has not been sufficiently investigated for granting occlusion times the role of an estimate of spare visual capacity. We conducted a driving simulator experiment (N = 30) and investigated if there is an association between drivers’ occlusion times and in-car glance durations in a given driving scenario. Furthermore, we explored which factors and variables could explain the strength of the association. The findings suggest an association between occlusion time preferences and in-car glance durations in visually and cognitively low demanding unstructured tasks but that this association is lost if the in-car task is more demanding. The findings might be explained by the inability to utilize peripheral vision for lane-keeping when conducting in-car tasks and/or by in-car task structures that override drivers’ preferences for the in-car glance durations. It seems that the occlusion technique could be utilized as an estimate of drivers’ spare visual capacity in research – but with caution. It is strongly recommended to use occlusion times in combination with driving performance metrics. There is less spare visual capacity if this capacity is used for secondary tasks that interfere with the driver’s ability to utilize peripheral vision for driving or preferences for the in-car glance durations. However, we suggest that the occlusion method can be a valid method to control for inter-individual differences in in-car glance duration preferences when investigating the visual distraction potential of, for instance, in-vehicle infotainment systems.
Objective: Neuropsychological patients often suffer from impairments in visual selective attention and processing capacity components. Their assessment demands a high standardization of testing ...conditions, which is difficult to achieve across institutions. Head-mounted displays (HMDs) provide a solution. These virtual reality devices cover the entire visual field in a shielded way and thus keep visual stimulation constant. For neuropsychological assessment with HMDs, sufficient reliability is required. We have previously demonstrated that an early developer version of an HMD can be used to reliably measure components of visual processing capacity. However, it is unclear whether this also holds for the assessment of components of visual selective attention. Moreover, it has yet to be established whether now commercially available HMDs are capable of reliable neuropsychological assessment. Method: We assessed the test-retest reliabilities of several components of visual selective attention and processing capacity of healthy subjects with the commercially available HTC Vive. Using an assessment procedure (combiTVA) derived from the theory of visual attention (TVA; Bundesen, 1990), we measured attentional selectivity, lateral bias, processing speed, visual working memory capacity, and the threshold of conscious perception. We compared the reliabilities of these components measured with the HTC Vive with those of a cathode ray tube (CRT) screen, the gold standard of visual presentation in the laboratory. Results: Both devices provided comparable reliabilities. Conclusions: Thus, HMDs fulfill the requirement to replace standard screens. With their inherent visual standardization and portability, they offer unprecedented opportunities for neuropsychological assessment, such as computerized bedside testing and comparisons of test values across institutions.
General Scientific Summary
With their inherent visual standardization and portability, head-mounted displays (HMDs) offer unprecedented opportunities for neuropsychological assessment, such as computerized bedside testing and comparisons across institutions. We assessed test-retest reliabilities of five components of visual selective attention and processing capacity by the HMD HTC Vive and a CRT, the current gold standard of visual presentation. Results show comparable reliability of both devices demonstrating that HMDs have the capability to advance the neuropsychological assessment to the next level.
The causes of the beaching and death of sea turtles have not been fully clarified and continue to be studied. Mild, moderate and severe lesions caused by spirorchiidiosis have been seen for decades ...in different organs and were recently defined as the cause of death of a loggerhead turtle. In the present study, eyes and optic nerves were analysed in green sea turtles with spirorchiidiosis and no other debilitating factors. Injuries to the optic nerve and choroid layer were described in 235 animals (90%) infected with spirorchiids. Turtles with ocular spirorchiidiosis are approximately three times more likely to be cachectic than turtles with spirorchiidiosis without ocular involvement.
This article describes the methodology and results of research on landscape visual capacity. The aim of the project was to develop a tool that would support planning and design decisions at the level ...of communal management in rural areas in Poland through systematic application of visual criteria. Their importance in the protection, management and shaping of space is underlined by the document produced at the European Landscape Convention of 2000 (ELC). To date, ELC recommendations have not been fully implemented in Poland. The author of the study used the methods of the Krakow School of Landscape Architecture in assessing cultural landscapes and referred to the assumptions of the British Landscape Character Assessment (LCA). The analysis was based on the results of a landscape identification conducted in a part of the Cekcyn commune. The assessment of visual capacity was conducted for the village of Nowy Sumin, located in that commune. The effect of the study is the classification of open landscapes with respect to the assessment of visual changes resulting from potential residential development. The results obtained prompt the conclusion that the applied method can effectively support local spatial planning as it takes national conditions into account.
The compound eyes of three taxa of Rhenish Lower Devonian eurypterids are examined and compared with those known from other eurypterids and the extant horseshoe crab Limulus polyphemus. The lateral ...eyes of the small species Rhenopterus diensti, a phylogenetically basal representative of the stylonurine clade, are characterized by a comparatively low number of lenses and high interommatidial angle Δφ (2.8°). The comparatively limited visual capacities of R. diensti are more similar to L. polyphemus than to its closer relatives of the eurypterine clade and perhaps this reflects a progression of lateral eye structure in the evolution of eurypterids as a whole. The number of eye facets in Adelophthalmus sievertsi is higher than that in the supposed ambush predator Acutiramus cummingsi, but lower than that in other ‘swimming’ eurypterids (Eurypterina). Due to poor preservation, no other eye parameters could be analysed in this species, but further morphological attributes and geographical distribution designate the mid‐sized A. sievertsi as an able swimmer. A low interommatidial angle Δφ of less than 1° confirms that the visual capacities of Jaekelopterus rhenaniae are in line with an interpretation of this giant species as an active high‐level predator. The inferred lifestyles of adult individuals of these three, co‐occurring Rhenish eurypterids indicate niche differentiation avoiding to some degree the competition for food in their marginal marine to delta plain transitional habitats.
Objective: To determine the prevalence of diabetic retinopathy and diabetic macular edema by means of retinography in patients diagnosed with Type 2 diabetes mellitus according to time of evolution ...and degree of vision loss with and without refractive correction.
Method: A descriptive cross-sectional study of 150 patients with Type 2 diabetes mellitus assessed in optometry in various health centers from the Sanitary Jurisdiction of Tlalpan, Health Services of Mexico City.
Results: 150 patients (70% women, 30% men) aged 60 (+/– 7.77) were diagnosed with Type 2 diabetesmellitus, 52% of them with an evolution of 12.09 years (+/– 3.48). Of the total number of patients, 72.33% had retinopathy and/or diabetic macular edema lesions. The average visual acuity improved from 0.62 (+/– 0.48) to 0.37 (+/– 0.38) with refractive correction, absolute disability decreased by –18.76% and null or slight disability increased by 31.31%. Of the total population, 75.5% remained under monitoring in primary care, and 24.5% were referred to tertiary care in ophthalmology.
Conclusion: The strategic opportunity to combat vision loss due to retinopathy and diabetic macular edema is found in its timely detection by health personnel trained in scrutiny and control at the primary care level, which would represent a decreased hospital load in tertiary care, thereby reducing costs for the health systems, as well as cost-efficiency for the years of sight gained and optimization of the patient’s global vision.
Objetivo: Determinar la prevalencia de retinopatía diabética y edema macular diabéticomediante retinografía en pacientes diagnosticados con diabetes mellitus tipo 2 según eltiempo de evolución y el grado de pérdida de visión con corrección refractiva sin esta.
Método: Estudio descriptivo de corte transversal de 150 pacientes con diabetes mellitus tipo2 evaluados en optometría, provenientes de diversos centros de salud pertenecientes a laJurisdicción Sanitaria de Tlalpan, Servicios de Salud de la Ciudad de México.
Resultados: 150 pacientes (70% mujeres, 30% hombres) de 60 años (± 7,77) fueron diagnosticados condiabetes mellitus tipo 2 (52%) con una evolución de 12,09 años (± 3,48). El 72,33% tieneretinopatía y/o lesiones de edema macular diabético. La agudeza visual promedio mejoróde 0,62 (± 0,48) a 0,37 (± 0,38) con corrección refractiva; la discapacidad absoluta disminuyóen −18,76% y la discapacidad nula o leve aumentó en 31,31%.
Conclusión: Existe una oportunidad estratégica para combatir la pérdida de visión debido a retinopatía y edema macular diabético en la detección oportuna por parte del personal de salud capacitadoen examinación y control estratégicamente ubicado en el primer nivel de atención; estorepresentaría una reducción de la carga hospitalaria del tercer nivel, reduciendo así loscostos para los sistemas de salud, lo cual significaría rentabilidad por los años de visiónganados y optimizaría la visión global del paciente.
Visual processing speed in old age HABEKOST, THOMAS; VOGEL, ASMUS; ROSTRUP, EGILL ...
Scandinavian journal of psychology,
04/2013, Letnik:
54, Številka:
2
Journal Article
Recenzirano
Mental speed is a common concept in theories of cognitive aging, but it is difficult to get measures of the speed of a particular psychological process that are not confounded by the speed of other ...processes. We used Bundesen’s (1990) Theory of Visual Attention (TVA) to obtain specific estimates of processing speed in the visual system controlled for the influence of response latency and individual variations of the perception threshold. A total of 33 non‐demented old people (69–87 years) were tested for the ability to recognize briefly presented letters. Performance was analyzed by the TVA model. Visual processing speed decreased approximately linearly with age and was on average halved from 70 to 85 years. Less dramatic aging effects were found for the perception threshold and the visual apprehension span. In the visual domain, cognitive aging seems to be most clearly related to reductions in processing speed.
Although good visual capacity is essential for children’s learning, we have limited understanding of the various visual functions among school starters. In order to extend this knowledge, a ...small-scale study was undertaken involving 24 preschool children age 5–6 years who completed a test battery originally designed for visual impairment specialists to measure visual acuity for distance and close work, and for visual attention and reaction capacity in the field of vision. The results revealed that school starters have a less mature visual acuity at a close reading distance than at a far distance. In this group, there were significant gender differences in visual acuity and reaction time in the visual field. This article discusses whether the level of visual development and gender differences may influence how pupils react, behave and learn in school, and questions whether this insight ought to have an impact on our expectations with regard to children’s school performance. In the context of pressures to begin formal teaching of literacy and numeracy earlier in some countries, the question of visual readiness becomes critical. The question should also make educators alert to the dangers of expecting all children to succeed in learning to read at the same early age, and of labelling those who do not succeed in making an early start as intellectually deficient.
This study addresses the limitation of patients’ visual experience in a healthcare environment. Clarity of visual experience occurs within the visual sphere that represents the seeing capacity ...defined by focus and peripheral view. The visual sphere is formed by the collections of “puff”- the unidentified parts as the components that create the wholeness of form in visual perception. This paper argues that the characters of puffs and their relationship could play an essential role in the formation of figure and ground. A simulation study was conducted by capturing the perceived scenes in a simulated patient room and then analyzing the character of regions in the scenes and their level of relationship. The study displayed the relationship between the region's position and the region's characters that form the integrity of the whole visual scenes. Knowledge of this relationship indicates that puff identification can be useful for evaluating the potential architecture elements within the visual capacity.
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