Development of sampling efficiency and internal noise in motion detection and discrimination in school-aged children

AbstractThe aim of this study was to use an equivalent noise paradigm to investigate the development and maturation of motion perception, and how the underlying limitations of sampling efficiency and internal noise effect motion detection and direction discrimination in school-aged children (5–14years) and adults. Contrast energy thresholds of a 2c/deg sinusoidal grating drifting at 1.0 or 6.0Hz were measured as a function of added dynamic noise in three tasks: detection of a drifting grating; detection of the sum of two oppositely drifting gratings and direction discrimination of oppositely drifting gratings. Compared to the ideal observer, in both children and adults, the performance for all tasks was limited by reduced sampling efficiency and internal noise. However, the thresholds for discrimination of motion direction and detection of moving gratings show very different developmental profiles. Motion direction discrimination continues to improve after the age of 14years due to an increase in sampling efficiency that differs with speed. Motion detection and summation were already mature at the age of 5years, and internal noise was the same for all tasks. These findings were confirmed in a 1-year follow-up study on a group of children from the initial study. The results support suggestions that the detection of a moving pattern and discriminating motion direction are processed by different systems that may develop at different rates

Acuity, crowding, reading and fixation stability

AbstractPeople with age-related macular disease frequently experience reading difficulty that could be attributed to poor acuity, elevated crowding or unstable fixation associated with peripheral visual field dependence. We examine how the size, location, spacing and instability of retinal images affect the visibility of letters and words at different eccentricities. Fixation instability was simulated in normally sighted observers by randomly jittering single or crowded letters or words along a circular arc of fixed eccentricity. Visual performance was assessed at different levels of instability with forced choice measurements of acuity, crowding and reading speed in a rapid serial visual presentation paradigm. In the periphery: (1) acuity declined; (2) crowding increased for acuity- and eccentricity-corrected targets; and (3), the rate of reading fell with acuity-, crowding- and eccentricity-corrected targets. Acuity and crowding were unaffected by even high levels of image instability. However, reading speed decreased with image instability, even though the visibility of the component letters was unaffected. The results show that reading performance cannot be standardised across the visual field by correcting the size, spacing and eccentricity of letters or words. The results suggest that unstable fixation may contribute to reading difficulties in people with low vision and therefore that rehabilitation may benefit from fixation training

The Person-centred Curriculum Framework: a universal curriculum framework for person-centred healthcare practitioner education

Background: Globally, humanising healthcare is a strategic response to a distinct need for person-centred approaches to practice. This movement has largely focused on the artefacts of healthcare practice, with an emergent focus on the role of healthcare education in instilling and espousing the core principles of person-centredness. It is increasingly recognised that how healthcare professionals are educated is fundamental to creating learning cultures where person-centred philosophies can be lived out and aligned with workforce and healthcare policy strategies. In 2019, six European countries began collaboration on an Erasmus+ project, Person-centredness in Healthcare Curricula, to develop a Person-centred Curriculum Framework. The other articles in this Special Issue focus on the methodologies employed by the project team, and this article describes the framework. Aim: While curricula exist with person-centredness as a focus, aim or component, few embrace person-centredness as an underpinning philosophy and theory, or use a whole-systems approach. This project aimed to develop a universal curricular framework with the agility to work synergistically with existing curricular processes, in pursuit of the development of person-centred healthcare practitioners and cultures. Methods: The project used an iterative multiphase, mixed methods approach, including an e-survey and interviews. Drawing on authentic co-design principles, to create our framework we engaged with stakeholders in clinical practice and academic institutions as well as healthcare students and those working in health policy and strategic workforce planning. Results: We present a framework for the design, delivery and evaluation of curricula, structured using a modified version of McKinsey’s 7S methodology, resulting in each component having a statement, outcomes, and thematic actions to support the realisation of a person-centred curriculum. Conclusion: Our Person-centred Curriculum Framework can facilitate congruency between healthcare education and practice in the way person-centredness is defined and lived out through healthful cultures. Given the iterative origins of the framework, we anticipate its evolution over time through further exploration following its implementation and evaluation

Development of radial optic flow pattern sensitivity at different speeds

AbstractThe development of sensitivity to radial optic flow discrimination was investigated by measuring motion coherence thresholds (MCTs) in school-aged children at two speeds. A total of 119 child observers aged 6–16years and 24 young adult observers (23.66+/−2.74years) participated. In a 2AFC task observers identified the direction of motion of a 5° radial (expanding vs. contracting) optic flow pattern containing 100 dots with 75% Michelson contrast moving at 1.6°/s and 5.5°/s and. The direction of each dot was drawn from a Gaussian distribution whose standard deviation was either low (similar directions) or high (different directions). Adult observers also identified the direction of motion for translational (rightward vs. leftward) and rotational (clockwise vs. anticlockwise) patterns. Motion coherence thresholds to radial optic flow improved gradually with age (linear regression, p<0.05), with different rates of development at the two speeds. Even at 16years MCTs were higher than that for adults (independent t-tests, p<0.05). Both children and adults had higher sensitivity at 5.5°/s compared to 1.6°/s (paired t-tests, p<0.05). Sensitivity to radial optic flow is still immature at 16years of age, indicating late maturation of higher cortical areas. Differences in sensitivity and rate of development of radial optic flow at the different speeds, suggest that different motion processing mechanisms are involved in processing slow and fast speeds

An ideal observer approach to development of motion perception in normal and abnormal vision

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Sources of Motion-Sensitivity Loss in Glaucoma

International audienc