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Laycox CA, Thompson R, Haggerty JA, Wilkins AJ, Haigh SM. Flicker and reading speed: Effects on individuals with visual sensitivity. Perception 2024:3010066241252066. [PMID: 38711325 DOI: 10.1177/03010066241252066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Flicker and patterns of stripes in the modern environment can evoke visual illusions, discomfort migraine, and seizures. We measured reading speed while striped and less striped texts were illuminated with LED lights. In Experiment 1, the lights flickered at 60 Hz and 120 Hz compared to 60 kHz (perceived as steady light). In Experiment 2, the lights flickered at 60 Hz or 600 Hz (at which frequency the phantom array is most visible), and were compared to continuous light. Two types of text were used: one containing words with high horizontal autocorrelation (striped) and another containing words with low autocorrelation (less striped). We measured the number of illusions participants saw in the Pattern Glare (PG) Test. Overall, reading speed was slowest during the 60 Hz and 600 Hz flicker and was slower when reading the high autocorrelation text. Interestingly, the low PG group showed greater effects of flicker on reading speed than the high PG group, which tended to be slower overall. In addition, reading speed in the high PG group was reduced when the autocorrelation of the text was high. These findings suggest that uncomfortable visual environments reduce reading efficiency, the more so in individuals who are visually sensitive.
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Wong SMY, Tang EYH, Hui CLM, Suen YN, Chan SKW, Lee EHM, Chan KT, Wong MTH, Wilkins AJ, Chen EYH. Excessive fear of clusters of holes, its interaction with stressful life events and the association with anxiety and depressive symptoms: large epidemiological study of young people in Hong Kong. BJPsych Open 2023; 9:e151. [PMID: 37577835 PMCID: PMC10594086 DOI: 10.1192/bjo.2023.540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 07/03/2023] [Accepted: 07/03/2023] [Indexed: 08/15/2023] Open
Abstract
BACKGROUND Excessive and persistent fear of clusters of holes, also known as trypophobia, has been suggested to reflect cortical hyperexcitability and may be associated with mental health risks. No study, however, has yet examined these associations in representative epidemiological samples. AIMS To examine the prevalence of trypophobia in a population-representative youth sample, its association with mental health and functioning, and its interaction with external stress. METHOD A total of 2065 young people were consecutively recruited from a household-based epidemiological youth mental health study in Hong Kong. Trypophobia, symptoms of anxiety, depression and stress, and exposure to personal stressors were assessed. Logistic regression was used to assess the relationships between trypophobia and mental health. Potential additive and interaction effects of trypophobia and high stress exposure on mental health were also tested. RESULTS The prevalence of trypophobia was 17.6%. Trypophobia was significantly associated with severe symptoms of anxiety (odds ratio (OR) = 1.83, 95% CI = 1.32-2.53), depression (OR = 1.78, 95% CI = 1.24-2.56) and stress (OR = 1.68, 95% CI = 1.11-2.53), even when accounting for sociodemographic factors, personal and family psychiatric history, resilience and stress exposure. Dose-response relationships were observed, and trypophobia significantly potentiated the effects of stress exposure on symptom outcomes, particularly for depressive symptoms. Those with trypophobia also showed significantly poorer functioning across domains and poorer health-related quality of life. CONCLUSIONS Screening for trypophobia in young people may facilitate early risk detection and intervention, particularly among those with recent stress exposure. Nevertheless, the generally small effect sizes suggest that other factors have more prominent roles in determining recent mental health outcomes in population-based samples; these should be explored in future work.
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Affiliation(s)
- Stephanie M. Y. Wong
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Eric Y. H. Tang
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Christy L. M. Hui
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Y. N. Suen
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Sherry K. W. Chan
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong; and The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong
| | - Edwin H. M. Lee
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - K. T. Chan
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Michael T. H. Wong
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong
| | | | - Eric Y. H. Chen
- Department of Psychiatry, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong
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Penacchio O, Otazu X, Wilkins AJ, Haigh SM. A mechanistic account of visual discomfort. Front Neurosci 2023; 17:1200661. [PMID: 37547142 PMCID: PMC10397803 DOI: 10.3389/fnins.2023.1200661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 06/27/2023] [Indexed: 08/08/2023] Open
Abstract
Much of the neural machinery of the early visual cortex, from the extraction of local orientations to contextual modulations through lateral interactions, is thought to have developed to provide a sparse encoding of contour in natural scenes, allowing the brain to process efficiently most of the visual scenes we are exposed to. Certain visual stimuli, however, cause visual stress, a set of adverse effects ranging from simple discomfort to migraine attacks, and epileptic seizures in the extreme, all phenomena linked with an excessive metabolic demand. The theory of efficient coding suggests a link between excessive metabolic demand and images that deviate from natural statistics. Yet, the mechanisms linking energy demand and image spatial content in discomfort remain elusive. Here, we used theories of visual coding that link image spatial structure and brain activation to characterize the response to images observers reported as uncomfortable in a biologically based neurodynamic model of the early visual cortex that included excitatory and inhibitory layers to implement contextual influences. We found three clear markers of aversive images: a larger overall activation in the model, a less sparse response, and a more unbalanced distribution of activity across spatial orientations. When the ratio of excitation over inhibition was increased in the model, a phenomenon hypothesised to underlie interindividual differences in susceptibility to visual discomfort, the three markers of discomfort progressively shifted toward values typical of the response to uncomfortable stimuli. Overall, these findings propose a unifying mechanistic explanation for why there are differences between images and between observers, suggesting how visual input and idiosyncratic hyperexcitability give rise to abnormal brain responses that result in visual stress.
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Affiliation(s)
- Olivier Penacchio
- Department of Computer Science, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Computer Vision Center, Universitat Autònoma de Barcelona, Bellaterra, Spain
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, United Kingdom
| | - Xavier Otazu
- Department of Computer Science, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Computer Vision Center, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Arnold J. Wilkins
- Department of Psychology, University of Essex, Colchester, United Kingdom
| | - Sarah M. Haigh
- Department of Psychology, University of Nevada Reno, Reno, NV, United States
- Institute for Neuroscience, University of Nevada Reno, Reno, NV, United States
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Fisher RS, Acharya JN, Baumer FM, French JA, Parisi P, Solodar JH, Szaflarski JP, Thio LL, Tolchin B, Wilkins AJ, Kasteleijn-Nolst Trenité D. Visually sensitive seizures: An updated review by the Epilepsy Foundation. Epilepsia 2022; 63:739-768. [PMID: 35132632 DOI: 10.1111/epi.17175] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 01/10/2022] [Accepted: 01/12/2022] [Indexed: 12/19/2022]
Abstract
Light flashes, patterns, or color changes can provoke seizures in up to 1 in 4000 persons. Prevalence may be higher because of selection bias. The Epilepsy Foundation reviewed light-induced seizures in 2005. Since then, images on social media, virtual reality, three-dimensional (3D) movies, and the Internet have proliferated. Hundreds of studies have explored the mechanisms and presentations of photosensitive seizures, justifying an updated review. This literature summary derives from a nonsystematic literature review via PubMed using the terms "photosensitive" and "epilepsy." The photoparoxysmal response (PPR) is an electroencephalography (EEG) phenomenon, and photosensitive seizures (PS) are seizures provoked by visual stimulation. Photosensitivity is more common in the young and in specific forms of generalized epilepsy. PS can coexist with spontaneous seizures. PS are hereditable and linked to recently identified genes. Brain imaging usually is normal, but special studies imaging white matter tracts demonstrate abnormal connectivity. Occipital cortex and connected regions are hyperexcitable in subjects with light-provoked seizures. Mechanisms remain unclear. Video games, social media clips, occasional movies, and natural stimuli can provoke PS. Virtual reality and 3D images so far appear benign unless they contain specific provocative content, for example, flashes. Images with flashes brighter than 20 candelas/m2 at 3-60 (particularly 15-20) Hz occupying at least 10 to 25% of the visual field are a risk, as are red color flashes or oscillating stripes. Equipment to assay for these characteristics is probably underutilized. Prevention of seizures includes avoiding provocative stimuli, covering one eye, wearing dark glasses, sitting at least two meters from screens, reducing contrast, and taking certain antiseizure drugs. Measurement of PPR suppression in a photosensitivity model can screen putative antiseizure drugs. Some countries regulate media to reduce risk. Visually-induced seizures remain significant public health hazards so they warrant ongoing scientific and regulatory efforts and public education.
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Affiliation(s)
- Robert S Fisher
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA
| | - Jayant N Acharya
- Department of Neurology, Penn State Health, Hershey, Pennsylvania, USA
| | - Fiona Mitchell Baumer
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA
| | - Jacqueline A French
- NYU Comprehensive Epilepsy Center, Epilepsy Foundation, New York, New York, USA
| | - Pasquale Parisi
- Department of Neuroscience, Mental Health, and Sensory Organs, Sapienza University, Rome, Italy
| | - Jessica H Solodar
- American Medical Writers Association-New England Chapter, Boston, Massachusetts, USA
| | - Jerzy P Szaflarski
- Department of Neurology, Neurobiology and Neurosurgery, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, Alabama, USA
| | - Liu Lin Thio
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Benjamin Tolchin
- Department of Neurology, Yale School of Medicine, New Haven, Connecticut, USA
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Penacchio O, Haigh SM, Ross X, Ferguson R, Wilkins AJ. Visual Discomfort and Variations in Chromaticity in Art and Nature. Front Neurosci 2021; 15:711064. [PMID: 34987354 PMCID: PMC8720932 DOI: 10.3389/fnins.2021.711064] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 11/22/2021] [Indexed: 11/13/2022] Open
Abstract
Visual discomfort is related to the statistical regularity of visual images. The contribution of luminance contrast to visual discomfort is well understood and can be framed in terms of a theory of efficient coding of natural stimuli, and linked to metabolic demand. While color is important in our interaction with nature, the effect of color on visual discomfort has received less attention. In this study, we build on the established association between visual discomfort and differences in chromaticity across space. We average the local differences in chromaticity in an image and show that this average is a good predictor of visual discomfort from the image. It accounts for part of the variance left unexplained by variations in luminance. We show that the local chromaticity difference in uncomfortable stimuli is high compared to that typical in natural scenes, except in particular infrequent conditions such as the arrangement of colorful fruits against foliage. Overall, our study discloses a new link between visual ecology and discomfort whereby discomfort arises when adaptive perceptual mechanisms are overstimulated by specific classes of stimuli rarely found in nature.
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Affiliation(s)
- Olivier Penacchio
- School of Psychology and Neuroscience, University of St. Andrews, St. Andrews, United Kingdom
| | - Sarah M. Haigh
- Department of Psychology, University of Nevada Reno, Reno, NV, United States
- Center for Integrative Neuroscience, University of Nevada Reno, Reno, NV, United States
| | - Xortia Ross
- Department of Psychology, University of Nevada Reno, Reno, NV, United States
| | - Rebecca Ferguson
- Department of Psychology, University of Nevada Reno, Reno, NV, United States
| | - Arnold J. Wilkins
- Department of Psychology, University of Essex, Colchester, United Kingdom
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Ross X, Haigh SM, Penacchio O, Wilkins AJ. Discomfort from Contemporary Art: Contribution of Color. J Vis 2021. [DOI: 10.1167/jov.21.9.2959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Brinciotti M, Wilkins AJ, Penacchio O, Matricardi M. Pattern-sensitive patients with epilepsy use uncomfortable visual stimuli to self-induce seizures. Epilepsy Behav 2021; 122:108189. [PMID: 34252828 DOI: 10.1016/j.yebeh.2021.108189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 06/07/2021] [Accepted: 06/24/2021] [Indexed: 10/20/2022]
Abstract
Sensory stimuli can induce seizures in patients with epilepsy and predisposed subjects. Visual stimuli are the most common triggers, provoking seizures through an abnormal response to light or pattern. Sensitive patients may intentionally provoke their seizures through visual stimuli. Self-induction methods are widely described in photo-sensitive patients, while there are only a few reports of those who are pattern-sensitive. We analyzed 73 images of environmental visual triggers collected from 14 pattern-sensitive patients with self-induced seizures. The images were categorized according to their topics: 29 Objects (43%); 19 Patterns (28%); 15 External scenes (22%); 4 TV or computer screens (6%). Six photos were of poor quality and were excluded from analysis. Images were analyzed by an algorithm that calculated the degree to which the Fourier amplitude spectrum differed from that in images from nature. The algorithm has been shown to predict discomfort in healthy observers. The algorithm identified thirty-one images (46%) as "uncomfortable". There were significant differences between groups of images (ANOVA p = .0036; Chi2 p < .0279), with higher values of difference from nature in the images classified as "Objects" (mean 6,81E+11; SD 6,72E+11; n.17, 59%) and "Pattern" (mean 9,05E+11; SD 6,86E+11; n.14, 74%). During the semi-structured face-to-face interviews, all patients described the visual triggers as 'uncomfortable'; the appearance of enjoyable visual epileptic symptoms (especially multi-colored hallucinations) transformed uncomfortable images into pleasant stimuli. Patients considered self-induction as the simplest and most effective way to overcome stressful situations, suggesting that self-inducing pattern-sensitive patients often use uncomfortable visual stimuli to trigger their seizures. Among the reasons for the self-inducing behavior, the accidental discovery of pleasurable epileptic symptoms related to these "uncomfortable" visual stimuli should be considered.
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Affiliation(s)
- Mario Brinciotti
- Department of Human Neuroscience, Sapienza University of Rome, Italy.
| | | | - Olivier Penacchio
- School of Psychology and Neuroscience, University of St Andrews, United Kingdom.
| | - Maria Matricardi
- Department of Human Neuroscience, Sapienza University of Rome, Italy.
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Abstract
Photophobia is one of the most common symptoms in migraine, and the underlying mechanism is uncertain. The discovery of the intrinsically-photosensitive retinal ganglion cells which signal the intensity of light on the retina has led to discussion of their role in the pathogenesis of photophobia. In the current review, we discuss the relationship between pain and discomfort leading to light aversion (traditional photophobia) and discomfort from flicker, patterns, and colour that are also common in migraine and cannot be explained solely by the activity of intrinsically-photosensitive retinal ganglion cells. We argue that, at least in migraine, a cortical mechanism provides a parsimonious explanation for discomfort from all forms of visual stimulation, and that the traditional definition of photophobia as pain in response to light may be too restrictive. Future investigation that directly compares the retinal and cortical contributions to photophobia in migraine with that in other conditions may offer better specificity in identifying biomarkers and possible mechanisms to target for treatment.
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Affiliation(s)
| | - Sarah M Haigh
- Department of Psychology and Integrative Neuroscience, University of Nevada, Reno, USA
| | - Omar A Mahroo
- Institute of Ophthalmology, University College London, London, UK and Retinal Service, Moorfields Eye Hospital, London, UK
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9
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Monger LJ, Shah D, Wilkins AJ, Allen PM. The effect of viewing distance on responses to the pattern glare test. Clin Exp Optom 2021; 99:47-50. [DOI: 10.1111/cxo.12364] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 04/01/2015] [Accepted: 04/06/2015] [Indexed: 11/27/2022] Open
Affiliation(s)
- Laura J Monger
- Department of Vision and Hearing Sciences and Vision and Eye Research Unit, Anglia Ruskin University, Cambridge, UK,
| | - Dhruvi Shah
- Department of Vision and Hearing Sciences and Vision and Eye Research Unit, Anglia Ruskin University, Cambridge, UK,
| | - Arnold J Wilkins
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester, UK,
| | - Peter M Allen
- Department of Vision and Hearing Sciences and Vision and Eye Research Unit, Anglia Ruskin University, Cambridge, UK,
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Yoshimoto S, Jiang F, Takeuchi T, Wilkins AJ, Webster MA. Visual discomfort from flicker: Effects of mean light level and contrast. Vision Res 2020; 173:50-60. [PMID: 32474213 DOI: 10.1016/j.visres.2020.05.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 05/11/2020] [Accepted: 05/11/2020] [Indexed: 11/18/2022]
Abstract
Uncomfortable images generally have a particular spatial structure, which deviates from a reciprocal relationship between amplitude and spatial frequency (f) in the Fourier domain (1/f). Although flickering patterns with similar temporal structure also appear uncomfortable, the discomfort is affected by not only the amplitude spectrum but also the phase spectrum. Here we examined how discomfort from flicker with differing temporal profiles also varies as a function of the mean light level and luminance contrast of the stimulus. Participants were asked to rate discomfort for a 17° flickering uniform field at different light levels from scotopic to photopic. The flicker waveform was varied with a square wave or random phase spectrum and filtered by modulating the slope of the amplitude spectrum relative to 1/f. At photopic levels, the 1/f square wave flicker appeared most comfortable, whereas the discomfort from the random flicker increased monotonically as the slope of the amplitude spectrum decreased. This special status for the 1/f square wave condition was limited to photopic light levels. At the lower mesopic or scotopic levels, the effect of phase spectrum on the discomfort was diminished, with both phase spectra showing a monotonic change with the slope of the amplitude spectrum. We show that these changes cannot be accounted for by changes in the effective luminance contrast of the stimuli or by the responses from a linear model based on the temporal impulse responses under different light levels. However, discomfort from flicker is robustly correlated with judgments of the perceived naturalness of flicker across different contrasts and mean luminance levels.
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Affiliation(s)
- Sanae Yoshimoto
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Kagamiyama 1-7-1, Higashi-Hiroshima, Hiroshima 739-8521, Japan.
| | - Fang Jiang
- Department of Psychology, University of Nevada, Reno, 1664 N. Virginia Street, Reno, Nevada 89557, USA
| | - Tatsuto Takeuchi
- Department of Psychology, Japan Women's University, Tama-ku Nishi-ikuta 1-1-1, Kawasaki, Kanagawa 214-8565, Japan
| | - Arnold J Wilkins
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Michael A Webster
- Department of Psychology, University of Nevada, Reno, 1664 N. Virginia Street, Reno, Nevada 89557, USA
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Yoshimoto S, Jiang F, Takeuchi T, Wilkins AJ, Webster MA. Adaptation and visual discomfort from flicker. Vision Res 2019; 160:99-107. [PMID: 31091424 DOI: 10.1016/j.visres.2019.04.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 04/21/2019] [Accepted: 04/24/2019] [Indexed: 10/26/2022]
Abstract
Spatial images with unnatural amplitude spectra tend to appear uncomfortable. Analogous effects are found in the temporal domain, yet discomfort in flickering patterns is also strongly dependent on the phase spectrum. Here we examined how discomfort in temporal flicker is affected by adaptation to different amplitude and phase spectra. Adapting and test flicker were square wave or random phase transitions in a uniform field filtered by increasing (blurred) or decreasing (sharpened) the slope of the amplitude spectrum. Participants rated the level of discomfort or sharpness/blur for the test flicker. Before adaptation, square wave transitions were rated as most comfortable when they had "focused" edges, which were defined as characterized by 1/f amplitude spectra, while random phase transitions instead appeared more comfortable the more blurred they were. After adapting to blurred or sharpened transitions, both square wave and random phase flicker appeared more sharpened or blurred, respectively, and these effects were consistent with renormalization of perceived temporal focus. In comparison, adaptation affected discomfort in the two waveforms in qualitatively different ways, and exposure to the adapting stimulus tended to increase rather than decreased its perceived discomfort. These results point to a dissociation between the perceived amplitude spectrum and perceived discomfort, suggesting they in part depend on distinct processes. The results further illustrate the importance of the phase spectrum in determining visual discomfort from flickering patterns.
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Affiliation(s)
- Sanae Yoshimoto
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Kagamiyama 1-7-1, Higashi-Hiroshima, Hiroshima 739-8521, Japan.
| | - Fang Jiang
- Department of Psychology, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV 89557, USA.
| | - Tatsuto Takeuchi
- Department of Psychology, Japan Women's University, Tama-ku Nishi-ikuta 1-1-1, Kawasaki, Kanagawa 214-8565, Japan.
| | - Arnold J Wilkins
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK.
| | - Michael A Webster
- Department of Psychology, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV 89557, USA.
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Yoshimoto S, Garcia J, Jiang F, Wilkins AJ, Takeuchi T, Webster MA. Visual discomfort and flicker. Vision Res 2017; 138:18-28. [PMID: 28709920 DOI: 10.1016/j.visres.2017.05.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 04/11/2017] [Accepted: 05/25/2017] [Indexed: 11/18/2022]
Abstract
Flickering lights can be uncomfortable to look at and can induce seizures in observers with photosensitive epilepsy. However, the temporal characteristics contributing to these effects are not fully known. In the spatial domain, one identified source of visual discomfort is when images have Fourier amplitude spectra that deviate from the natural (∼1/frequency, 1/f) statistical characteristics of natural scenes, especially if they contain excess energy at the medium frequencies at which the visual system is most sensitive. We tested for analogous effects in the temporal domain, manipulating both the amplitude and phase spectra of the flicker. Participants judged the relative discomfort of temporal luminance variations in a pair of uniform 17° fields with different temporal modulations. In general, discomfort increased with deviations from natural amplitude spectra, particularly those with excess energy at medium frequencies or biased toward sharper spectra. These ratings of discomfort were also consistent with ratings of how natural the modulations appeared. However, the temporal discomfort judgments were also strongly affected by the phase spectra of the flicker, with fixed vs. random spectra producing very different responses. This was not due to the perceived regularity or predictability of the flicker, but could arise from a number of other potential factors. Our findings suggest that, like spatial patterns, visual discomfort in time-varying patterns depends in part on how similar they are to the amplitude spectra of temporal variations in the natural visual environment, but also point to the critical role of the phase spectrum in the perceived discomfort of flicker.
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Affiliation(s)
- Sanae Yoshimoto
- School of Psychology, Chukyo University, Showa-ku Yagotohonmachi 101-2, Nagoya, Aichi 466-8666, Japan; Department of Psychology, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV 89557, USA.
| | - Jesel Garcia
- Department of Psychology, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV 89557, USA.
| | - Fang Jiang
- Department of Psychology, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV 89557, USA.
| | - Arnold J Wilkins
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK.
| | - Tatsuto Takeuchi
- Department of Psychology, Japan Women's University, Tama-ku Nishi-ikuta 1-1-1, Kawasaki, Kanagawa 214-8565, Japan.
| | - Michael A Webster
- Department of Psychology, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV 89557, USA.
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Evans BJW, Allen PM, Wilkins AJ. A Delphi study to develop practical diagnostic guidelines for visual stress (pattern-related visual stress). J Optom 2017; 10:161-168. [PMID: 27890547 PMCID: PMC5484780 DOI: 10.1016/j.optom.2016.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 08/26/2016] [Accepted: 08/28/2016] [Indexed: 05/12/2023]
Abstract
PURPOSE Visual stress (VS) is characterised by symptoms of visual perceptual distortions and eyestrain when viewing text, symptoms that are alleviated by individually prescribed coloured filters. A recent review supports the existence of VS and its treatment, but noted that controversy remains, in part due to inconsistencies in the diagnosis of the condition. The present paper reviews the diagnostic criteria for VS in the literature and reports a Delphi analysis of the criteria currently used in clinical practice. METHODS Twenty-six eyecare practitioners were invited to participate in a Delphi study. They were selected because they were frequent prescribers of precision tinted lenses. In the first round they were sent a list of the indicators for which there is literature to suggest a relevance in the diagnosis of VS. The practitioners were invited to rank the indicators and add any additional criteria they use in diagnosis. In the second round a revised list was circulated, including items added from the responses in the first round. RESULTS The respondents included optometrists, orthoptists and opticians. In the first round the response rate was 85%. Ninety-one percent of those who participated in the first round also responded in the second round. Strong indicators in the second round included the symptom of words moving when reading, voluntary use of an overlay for a prolonged period, improved performance of ≥15% with an overlay on the Wilkins Rate of Reading test, and an abnormally high score on the Pattern Glare Test. CONCLUSIONS The strongest diagnostic criteria are combined in a diagnostic tool. This is proposed as a guide for clinical practice and further research.
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Affiliation(s)
- Bruce J W Evans
- Institute of Optometry, London, UK; Division of Optometry & Visual Science, City, University London, UK.
| | - Peter M Allen
- Department of Vision and Hearing Sciences and Vision and Eye Research Unit, Anglia Ruskin University, Cambridge, UK
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Ludlow AK, Wilkins AJ. Atypical Sensory behaviours in children with Tourette's Syndrome and in children with Autism Spectrum Disorders. Res Dev Disabil 2016; 56:108-116. [PMID: 27286465 DOI: 10.1016/j.ridd.2016.05.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 05/12/2016] [Accepted: 05/23/2016] [Indexed: 06/06/2023]
Abstract
Certain visual disturbances make it difficult to read text and have been attributed to visual stress, also called "pattern-related visual stress". 12 Children with ASD, 12 children with Tourette's syndrome and without ASD and 12 controls, all matched on age and non verbal ability, participated in an experiment exploring sensory behaviours and visual stress. Reading rate and accuracy were assessed with the Wilkins Rate of Reading test with and without the Intuitive Overlays. Both the children with Tourette's and the children with ASD showed a higher prevalence of atypical sensory behaviours and symptoms of visual stress than the typically developing control children. Six out of twelve children with Tourette's syndrome (50%) read more accurately and over 15% more quickly with a coloured overlay. Four of the 12 children with ASD and none of the control children read over 15% more quickly with an overlay. The findings are discussed in relation to problems in sensory modulation.
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Affiliation(s)
- Amanda K Ludlow
- University of Hertfordshire, College Lane, Hatfield, AL10 9AB, United Kingdom; University of Birmingham, Edgbaston, B15 2TT, United Kingdom.
| | - Arnold J Wilkins
- University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom.
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16
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Abstract
In a series of eight studies it is shown that the first peak in the horizontal autocorrelation of the image of a word (which captures the similarity in shape between the neighbouring strokes of letters) determines (i) the appearance of the words as striped; (ii) the speed with which the words are read, both aloud and silently; and (iii) the speed with which a paragraph of text can be searched. By subtly distorting the horizontal dimension of text, and thereby reducing the first peak in the horizontal autocorrelation, it is shown that the speed of word recognition can be increased. The increase in speed is greater in poor readers.
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Affiliation(s)
- Arnold J Wilkins
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Jennifer Smith
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Clare K Willison
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Tom Beare
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Alexandra Boyd
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Gemma Hardy
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Louise Mell
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Charlotte Peach
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Samantha Harper
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
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Engel SA, Wilkins AJ, Mand S, Helwig NE, Allen PM. Habitual wearers of colored lenses adapt more rapidly to the color changes the lenses produce. Vision Res 2016; 125:41-8. [PMID: 27264027 DOI: 10.1016/j.visres.2016.05.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 05/10/2016] [Accepted: 05/30/2016] [Indexed: 11/16/2022]
Abstract
The visual system continuously adapts to the environment, allowing it to perform optimally in a changing visual world. One large change occurs every time one takes off or puts on a pair of spectacles. It would be advantageous for the visual system to learn to adapt particularly rapidly to such large, commonly occurring events, but whether it can do so remains unknown. Here, we tested whether people who routinely wear spectacles with colored lenses increase how rapidly they adapt to the color shifts their lenses produce. Adaptation to a global color shift causes the appearance of a test color to change. We measured changes in the color that appeared "unique yellow", that is neither reddish nor greenish, as subjects donned and removed their spectacles. Nine habitual wearers and nine age-matched control subjects judged the color of a small monochromatic test light presented with a large, uniform, whitish surround every 5s. Red lenses shifted unique yellow to more reddish colors (longer wavelengths), and greenish lenses shifted it to more greenish colors (shorter wavelengths), consistent with adaptation "normalizing" the appearance of the world. In controls, the time course of this adaptation contained a large, rapid component and a smaller gradual one, in agreement with prior results. Critically, in habitual wearers the rapid component was significantly larger, and the gradual component significantly smaller than in controls. The total amount of adaptation was also larger in habitual wearers than in controls. These data suggest strongly that the visual system adapts with increasing rapidity and strength as environments are encountered repeatedly over time. An additional unexpected finding was that baseline unique yellow shifted in a direction opposite to that produced by the habitually worn lenses. Overall, our results represent one of the first formal reports that adjusting to putting on or taking off spectacles becomes easier over time, and may have important implications for clinical management.
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Affiliation(s)
- Stephen A Engel
- University of Minnesota, Department of Psychology, Minneapolis, MN, USA.
| | | | - Shivraj Mand
- Anglia Ruskin University, Department of Vision and Hearing Sciences, Cambridge, UK
| | | | - Peter M Allen
- Anglia Ruskin University, Department of Vision and Hearing Sciences, Cambridge, UK; Anglia Ruskin University, Vision and Eye Research Unit, Cambridge, UK
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18
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Myint J, Latham K, Mann D, Gomersall P, Wilkins AJ, Allen PM. The relationship between visual function and performance in rifle shooting for athletes with vision impairment. BMJ Open Sport Exerc Med 2016; 2:e000080. [PMID: 27900160 PMCID: PMC5117046 DOI: 10.1136/bmjsem-2015-000080] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/28/2015] [Indexed: 11/18/2022] Open
Abstract
Background Paralympic sports provide opportunities for those who have an impairment that might otherwise be a barrier to participation in regular sporting competition. Rifle shooting represents an ideal sport for persons with vision impairment (VI) because the direction of the rifle can be guided by auditory information when vision is impaired. However, it is unknown whether those with some remaining vision when shooting with auditory guidance would be at an advantage when compared with those with no vision at all. If this were the case then it would be necessary for those with and without remaining vision to compete in separate classes of competition. Materials and method The associations between shooting performance and 3 measures of visual function thought important for shooting were assessed for 10 elite VI shooters currently classified as VI. A conventional audiogram was also obtained. Results The sample size, though small, included the majority of European VI shooters competing at this level. The relationships between visual functions and performance confirmed that individuals with residual vision had no advantage over those without vision when auditory guidance was available. Auditory function was within normal limits for age, and showed no relationship with performance. Summary The findings suggest that rifle-shooting athletes with VI are able to use auditory information to overcome their impairment and optimise performance. Paralympic competition should be structured in a way that ensures that all shooters who qualify to compete in VI shooting participate within the same class irrespective of their level of VI.
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Affiliation(s)
- Joy Myint
- Postgraduate Medicine, Life and Medical Sciences , University of Hertfordshire , Hatfield , UK
| | - Keziah Latham
- Department of Vision and Hearing Sciences, Anglia Ruskin University, Cambridge, UK; Vision and Eye Research Unit, Anglia Ruskin University, Cambridge, UK
| | - David Mann
- Department of Human Movement Sciences , Research Institute MOVE Amsterdam, Vrije Universiteit Amsterdam , Amsterdam , The Netherlands
| | - Phil Gomersall
- Department of Vision and Hearing Sciences , Anglia Ruskin University , Cambridge , UK
| | - Arnold J Wilkins
- Department of Psychology , University of Essex , Colchester , UK
| | - Peter M Allen
- Department of Vision and Hearing Sciences, Anglia Ruskin University, Cambridge, UK; Vision and Eye Research Unit, Anglia Ruskin University, Cambridge, UK
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19
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Abstract
Aim: To test a theory of visual stress by investigating the inter-relationships between (1) the threshold contrast/saturation at which individuals first report discomfort when viewing colored gratings of progressively increasing contrast and decreasing saturation; (2) the choice of a colored overlay for reading; (3) any increase in reading speed when the overlay is used. Method: Ninety-five young adults, with normal color vision, reported illusions from square-wave gratings (Pattern Glare Test), chose any colored overlays that improved clarity (Intuitive Color Overlays) and read aloud randomly ordered common words (Wilkins Rate of Reading Test). This was followed by an automated choice of tints for text using various screen colors on a tablet, and a test of discomfort from patterns of progressively increasing contrast and decreasing saturation, using software developed for this study. All participants wore their optimal refractive correction throughout the procedure. Results: Fifty-eight participants chose a colored overlay and reported that it made text easier and more comfortable to read. On average, these individuals had a greater improvement in reading speed with their overlays (p = 0.003), a lower contrast threshold at which discomfort from achromatic gratings was first reported (p = 0.015), and a tendency to report more pattern glare (p = 0.052), compared to the other participants. Participants who chose both a most and least preferred tint for text using the automated procedure reported discomfort from colored gratings at a significantly higher contrast with their most preferred color compared to their least preferred color (p = 0.003). The choice of a colored tint was moderately consistent across tests. The most and least preferred colors tended to be complementary. Conclusion: Colored tints that improved reading speed reduced pattern glare both in terms of the illusion susceptibility and in terms of discomfort contrast threshold, supporting a theory of visual stress. An automated test that incorporates colored gratings and a choice of most and least preferred color might better identify individuals whose reading speed improves with colored overlays.
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Affiliation(s)
- Laura J Monger
- Department of Vision and Hearing Sciences, Anglia Ruskin University Cambridge, England
| | - Arnold J Wilkins
- Department of Psychology, University of Essex Colchester, England
| | - Peter M Allen
- Department of Vision and Hearing Sciences, Anglia Ruskin University Cambridge, England ; Vision and Eye Research Unit, Anglia Ruskin University Cambridge, England
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Whitaker L, Jones CRG, Wilkins AJ, Roberson D. Judging the Intensity of Emotional Expression in Faces: the Effects of Colored Tints on Individuals With Autism Spectrum Disorder. Autism Res 2015; 9:450-9. [PMID: 26058998 DOI: 10.1002/aur.1506] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 05/07/2015] [Indexed: 11/09/2022]
Abstract
Individuals with autism spectrum disorder (ASD) often show atypical processing of facial expressions, which may result from visual stress. In the current study, children with ASD and matched controls judged which member of a pair of faces displayed the more intense emotion. Both faces showed anger, disgust, fear, happiness, sadness or surprise but to different degrees. Faces were presented on a monitor that was tinted either gray or with a color previously selected by the participant individually as improving the clarity of text. Judgments of emotional intensity improved significantly with the addition of the preferred colored tint in the ASD group but not in controls, a result consistent with a link between visual stress and impairments in processing facial expressions in individuals with ASD.
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Affiliation(s)
- Lydia Whitaker
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester, United Kingdom
| | - Catherine R G Jones
- School of Psychology, Cardiff University, Tower Building, Park Place, Cardiff, United Kingdom
| | - Arnold J Wilkins
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester, United Kingdom
| | - Debi Roberson
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester, United Kingdom
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21
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Abstract
We developed and validated a symptom scale that can be used to identify "trypophobia", in which individuals experience aversion induced by images of clusters of circular objects. The trypophobia questionnaire (TQ) was based on reports of various symptom types, but it nevertheless demonstrated a single construct, with high internal consistency and test-retest reliability. The TQ scores predicted discomfort from trypophobic images, but not neutral or unpleasant images, and did not correlate with anxiety. Using image filtering, we also reduced the excess energy at midrange spatial frequencies associated with both trypophobic and uncomfortable images. Relative to unfiltered trypophobic images, the discomfort from filtered images experienced by observers with high TQ scores was less than that experienced with control images and by observers with low TQ scores. Furthermore, we found that clusters of concave objects (holes) did not induce significantly more discomfort than clusters of convex objects (bumps), suggesting that trypophobia involves images with particular spectral profile rather than clusters of holes per se.
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Affiliation(s)
- An T D Le
- a Department of Psychology , University of Essex , Colchester , UK
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22
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Braithwaite JJ, Broglia E, Brincat O, Stapley L, Wilkins AJ, Takahashi C. Signs of increased cortical hyperexcitability selectively associated with spontaneous anomalous bodily experiences in a nonclinical population. Cogn Neuropsychiatry 2014; 18:549-73. [PMID: 23441857 DOI: 10.1080/13546805.2013.768176] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
INTRODUCTION The current study examined the presence of cortical hyperexcitability, in nonclinical hallucinators, reporting different forms of anomalous bodily experiences (ABEs). Groups reporting visual out-of-body experiences and nonvisual sensed-presence experiences were examined. It was hypothesised that only those hallucinators whose experiences contained visual elements would show increased signs of visual cortical hyperexcitability. METHODS One hundred and eighty-two participants completed the "Pattern-glare task" (involving the viewing of striped gratings with spatial frequencies irritable to visual cortex)-a task known to reflect degrees of cortical hyperexcitability associated with hallucinatory/aura experiences in neurological samples. Participants also completed questionnaire measures of anomalous "temporal-lobe experience" and predisposition to anomalous visual experiences. RESULTS Those reporting increased levels of anomalous bodily experiences provided significantly elevated scores on measures of temporal-lobe experience. Only the visual OBE group reported significantly elevated levels of cortical hyperexcitability as assessed by the pattern-glare task. CONCLUSIONS Collectively, the results are consistent with there being an increased degree of background cortical hyperexcitability in the cortices of individuals predisposed to some ABE-type hallucinations, even in the nonclinical population. The present study also establishes the clinical utility of the pattern-glare task for examining signs of aberrant visual connectivity in relation to visual hallucinations.
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Affiliation(s)
- Jason J Braithwaite
- a Behavioural Brain Sciences Centre, School of Psychology , University of Birmingham , Birmingham , UK
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23
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Abstract
Phobias are usually described as irrational and persistent fears of certain objects or situations, and causes of such fears are difficult to identify. We describe an unusual but common phobia (trypophobia), hitherto unreported in the scientific literature, in which sufferers are averse to images of holes. We performed a spectral analysis on a variety of images that induce trypophobia and found that the stimuli had a spectral composition typically associated with uncomfortable visual images, namely, high-contrast energy at midrange spatial frequencies. Critically, we found that a range of potentially dangerous animals also possess this spectral characteristic. We argue that although sufferers are not conscious of the association, the phobia arises in part because the inducing stimuli share basic visual characteristics with dangerous organisms, characteristics that are low level and easily computed, and therefore facilitate a rapid nonconscious response.
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Braithwaite JJ, Broglia E, Bagshaw AP, Wilkins AJ. Evidence for elevated cortical hyperexcitability and its association with out-of-body experiences in the non-clinical population: New findings from a pattern-glare task. Cortex 2013; 49:793-805. [DOI: 10.1016/j.cortex.2011.11.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 09/22/2011] [Accepted: 11/10/2011] [Indexed: 11/26/2022]
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25
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Abstract
Grating patterns can cause discomfort and perceptual distortions. Individuals who experience discomfort and are susceptible to these distortions generally show weaker accommodation than those who are less susceptible. We measured the accommodative response to grating patterns known to differ in the discomfort they evoke because of differences in their colour, motion, or spatial frequency. The parameters known to affect discomfort and distortion had no influence on the mean or variance in the accommodative response, even when accommodative demand was manipulated systematically and the accommodative response varied as expected.
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Affiliation(s)
- Sarah M Haigh
- Visual Perception Unit, Department of Psychology, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK
| | - Wolfgang Jaschinski
- Leibniz-Institute für Arbeitsforschung an der TU Dortmund, Ardeystrasse 67, D-44139 Dortmund, Germany
| | - Peter M Allen
- Vision and Eye Research Unit, Postgraduate Medical Institute, Anglia Ruskin University, Cambridge CB1 1PT, UK
| | - Arnold J Wilkins
- Visual Perception Unit, Department of Psychology, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK
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26
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Coutts LV, Cooper CE, Elwell CE, Wilkins AJ. Time course of the haemodynamic response to visual stimulation in migraine, measured using near-infrared spectroscopy. Cephalalgia 2012; 32:621-9. [DOI: 10.1177/0333102412444474] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Background: In patients with migraine, an abnormally large haemodynamic response to epileptogenic visual stimulation has previously been observed, consistent with the hypothesis of a cortical hyperexcitability. Ophthalmic filters have been used in the treatment of migraine, and they reduce the haemodynamic response. Methods: The present study used near-infrared spectroscopy (NIRS) to characterise the haemodynamic response to a range of visual stimuli in 20 patients with migraine (15 with aura and 5 without) and paired controls in order to assess the effect of ophthalmic treatment. In an initial study, the response to three stimuli (chequerboard, and two gratings of different spatial frequency) was measured. In a second study, using the mid-spatial frequency grating as stimulus, the response was compared when precision spectral filters (PSF), grey filters or filters of control colour were worn as ophthalmic lenses. Results: In the first study the time course of the response differed between the groups. The difference was most distinct for the grating with mid-spatial frequency. In the second study the PSF broadened (normalised) the haemodynamic response in migraineurs relative to controls, consistent with fMRI BOLD findings and suggesting a physiological mechanism for their reported efficacy. In neither study were there differences in the amplitude of the response between migraine and control groups or indeed between filters. Conclusion: The time course of the functional response as measured by NIRS may be an effective tool to track therapy with PSF and explore the mechanisms of visual stress in migraine.
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28
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Ludlow AK, Taylor-Whiffen E, Wilkins AJ. Coloured filters enhance the visual perception of social cues in children with autism spectrum disorders. ISRN Neurol 2012; 2012:298098. [PMID: 22523702 PMCID: PMC3316948 DOI: 10.5402/2012/298098] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 12/13/2011] [Indexed: 11/23/2022]
Abstract
Coloured filters have been found to reduce visual distortion of text in children with autism spectrum disorders (ASD). We investigated the effect of the overlays on the "mind in the eye" task in children with ASD and controls matched for age, gender, and nonverbal IQ. Children were shown photographs of the periocular region of various faces and were asked to judge which emotion was being expressed in the eyes. In children with ASD, the perception of the emotion was significantly improved when the photograph was covered by a coloured overlay. The improvement was significantly greater than in the controls, who showed no significant effect of the overlay. A perceptual impairment may contribute to the social difficulties shown in ASD.
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Affiliation(s)
- Amanda K Ludlow
- Department of Psychology, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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29
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Abstract
We manipulated the accommodative response using positive and negative lenses to study any association between symptoms of pattern glare and accommodation. Two groups of eighteen young adults were selected from seventy-eight on the basis (i) that their rate of reading increased by 5% or more with an overlay compared to their rate without it, and (ii) that they reported more than 2 symptoms of pattern glare (group 1) or had no such increment in reading speed and reported fewer than 3 symptoms (group 2). Under double-masked conditions participants observed at 0.4 m a pattern of stripes while measurements of accommodation were made using an open field autorefractor with and without positive and negative trial lenses (0.75 D), and with and without a coloured overlay. Pattern glare was also assessed with and without the trial lenses. Without lenses, the mean accommodative response in group 1 was 1.55 D, a lag of 0.95 D +/- 0.24 D relative to the demand. The lag decreased by 0.43 D (p < 0.0001) when the chosen overlay was used, an effect that was not shown in group 2 even when lag increased with negative trial lenses (p = 0.13). In both groups, pattern glare scores were reduced by the trial lenses, but were unaffected by the sign of the lenses. This suggests that symptoms of pattern glare are not strongly associated with accommodative response.
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Affiliation(s)
- Peter M Allen
- Vision and Eye Research Unit, Postgraduate Medical Institute, Cambridge CB1 1PT, UK.
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30
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Affiliation(s)
- Peter M. Allen
- From the Vision and Eye Research Unit, Postgraduate Medical Institute, Cambridge, United Kingdom; the 2Department of Vision and Hearing Sciences, Anglia Ruskin University, Cambridge, United Kingdom; and
| | - Atif Hussain
- the Department of Vision and Hearing Sciences, Anglia Ruskin University, Cambridge, United Kingdom; and
| | - Claire Usherwood
- the Department of Vision and Hearing Sciences, Anglia Ruskin University, Cambridge, United Kingdom; and
| | - Arnold J. Wilkins
- the Visual Perception Unit, Department of Psychology, University of Essex, Colchester, United Kingdom
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31
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Khalil NM, Nicotra A, Wilkins AJ. Asymmetry of visual function in migraine with aura: Correlation with lateralisation of headache and aura. Cephalalgia 2010; 31:213-21. [DOI: 10.1177/0333102410378050] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background: Asymmetry of visual phenomena and headache is an important feature of migraine with aura. Methods: This asymmetry was explored by assessment of visual illusions, hemifield spatial contrast detection (HCD) and hemifield pattern reversal visual evoked potentials (HVEPs) in 47 migraineurs with aura (MA), who were not taking prophylactic medications, and 62 controls with the same age range (16–59). Results: Illusions were greater and HCD was poorer in MA than in controls. There were no group differences with respect to P100 amplitude. The longer the duration of migraine the poorer the HCD. When the aura was consistently unilateral it was associated with greater illusions, reduced HCD and reduced hemifield P100 amplitude. These findings were not related to the side of headache. Conclusion: The lateralised changes suggest that the visual dysfunction occurs at a cortical level, and the correlation with the side of the aura suggests that dysfunction is most likely to occur in an area of preexisting anomaly of neural function.
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Affiliation(s)
- Nofal M Khalil
- Imperial College Healthcare NHS Trust and Charing Cross Hospital, UK
| | - Alessia Nicotra
- Imperial College Healthcare NHS Trust and Charing Cross Hospital, UK
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32
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Abstract
PURPOSE To determine the potential risk of epileptic seizures from wind turbine shadow flicker under various meteorologic conditions. METHODS We extend a previous model to include attenuation of sunlight by the atmosphere using the libradtran radiative transfer code. RESULTS Under conditions in which observers look toward the horizon with their eyes open we find that there is risk when the observer is closer than 1.2 times the total turbine height when on land, and 2.8 times the total turbine height in marine environments, the risk limited by the size of the image of the sun's disc on the retina. When looking at the ground, where the shadow of the blade is cast, observers are at risk only when at a distance <36 times the blade width, the risk limited by image contrast. If the observer views the horizon and closes their eyes, however, the stimulus size and contrast ratio are epileptogenic for solar elevation angles down to approximately 5 degrees. DISCUSSION Large turbines rotate at a rate below that at which the flicker is likely to present a risk, although there is a risk from smaller turbines that interrupt sunlight more than three times per second. For the scenarios considered, we find the risk is negligible at a distance more than about nine times the maximum height reached by the turbine blade, a distance similar to that in guidance from the United Kingdom planning authorities.
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Affiliation(s)
- Andrew R D Smedley
- School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, United Kingdom
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33
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Abstract
The ratings of discomfort from a wide variety of images can be predicted from the energy at different spatial scales in the image, as measured by the Fourier amplitude spectrum of the luminance. Whereas comfortable images show the regression of Fourier amplitude against spatial frequency common in natural scenes, uncomfortable images show a regression with disproportionately greater amplitude at spatial frequencies within two octaves of 3 cycles deg(-1). In six studies, the amplitude in this spatial frequency range relative to that elsewhere in the spectrum explains variance in judgments of discomfort from art, from images constructed from filtered noise, and from art in which the phase or amplitude spectra have been altered. Striped patterns with spatial frequency within the above range are known to be uncomfortable and capable of provoking headaches and seizures in susceptible persons. The present findings show for the first time that, even in more complex images, the energy in this spatial-frequency range is associated with aversion. We propose a simple measurement that can predict aversion to those works of art that have reached the national media because of negative public reaction.
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Affiliation(s)
- Dominic Fernandez
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
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Evans BJ, Patel R, Wilkins AJ, Lightstone A, Eperjesi F, Speedwell L, Duffy J. A review of the management of 323 consecutive patients seen in a specific learning difficulties clinic. Ophthalmic Physiol Opt 2008. [DOI: 10.1111/j.1475-1313.1999.00465.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
Not all visually sensitive patients need antiepileptic drug treatment, and even those who do can benefit from additional preventive measures. Visually provoked seizures, in particular, can be prevented or treated by avoiding or altering the triggering stimulus. Apart from individual preventive measures (use of specific television or video screens, colored glasses, etc.), prevention and warning on a larger scale are helpful. The choice for drug treatment will depend on the type of stimulus, the environment in which the person has to live and work, the frequency and severity of seizures, and the type of epileptic syndrome. A review is given of all treatment options with focus on the specific nonpharmacologic and pharmacologic tools used in clinical practice.
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36
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Abstract
Abnormalities of colour perception in children with autistic spectrum disorders have been widely reported anecdotally. However, there is little empirical data linking difficulties in colour perception with academic achievement. The Wilkins Rate of Reading Test was administered with and without Intuitive Coloured Overlays to 19 children with autistic spectrum disorders and to the same number of controls individually matched for age and intelligence. Findings showed that 15 out of 19 (79%) children with autism showed an improvement of at least 5% in reading speed when using a coloured overlay. In contrast only 3 of 19 (16%) control group children showed such an improvement. The findings suggest that coloured overlays may provide a useful support for reading for children with autism.
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Affiliation(s)
- Amanda K Ludlow
- Department of Psychology, Goldsmiths College, University of London, New Cross, London, UK.
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37
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Harding G, Wilkins AJ, Erba G, Barkley GL, Fisher RS. Photic- and Pattern-induced Seizures: Expert Consensus of the Epilepsy Foundation of America Working Group. Epilepsia 2005; 46:1423-5. [PMID: 16146438 DOI: 10.1111/j.1528-1167.2005.31305.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE In August, 2004, the Epilepsy Foundation of America convened a workshop to begin to develop an expert consensus on photosensitive seizures. METHODS Literature and data were reviewed, and consensus was derived from discussion. RESULTS A flash is a potential hazard if it has luminance >or=20 cd/m2, occurs at a frequency of >or=3 Hz, and occupies a solid visual angle of >or=0.006 steradians (approximately 10% of the central visual field or 25% of screen area at typical viewing distances). A transition to or from saturated red also is considered a risk. A pattern with the potential for provoking seizures contains clearly discernible stripes, numbering more than five light-dark pairs of stripes in any orientation. When the light-dark stripes of any pattern collectively subtend at the eye from the minimal-expected viewing distance a solid angle of >0.006 steradians, the luminance of the lightest stripe is >50 cd/m2, and the pattern is presented for >or=0.5 s, then the pattern should display no more than five light-dark pairs of stripes, if the stripes change direction, oscillate, flash, or reverse in contrast; if the pattern is unchanging or smoothly drifting in one direction, no more than eight stripes. These principles are easier to apply in the case of fixed media, for example, a prerecorded TV show, which can be analyzed frame-by-frame, as compared with interactive media. CONCLUSIONS A consensus view of stimuli likely to provoke visually evoked seizures can be developed.
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Affiliation(s)
- Graham Harding
- Clinical Neurophysiology Unit, Aston University, Birmingham, UK
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Wilkins AJ, Sihra N, Myers A. Increasing reading speed by using colours: issues concerning reliability and specificity, and their theoretical and practical implications. Perception 2005; 34:109-20. [PMID: 15773610 DOI: 10.1068/p5045] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
By using techniques for precision ophthalmic tinting, individuals who report perceptual distortion of text can often find a colour of illumination that eliminates the distortions and increases reading speed. Most individuals choose green or blue hues, but there is considerable variability. We investigated how specific the colour has to be to obtain optimal reading speed. Individuals who habitually wear coloured filters for reading were asked to read text illuminated by coloured light (without using their filters). Reading speed was measured repeatedly with light of different colours. The colour (chromaticity) at which reading was fastest was consistent from one test session to the next. It was different from one individual to another, but highly specific for each individual: departures of colour from optimum by about 6 JNDs eliminated most of the speed advantage conferred by the optimal colour. It was difficult to attribute the consistency and specificity simply to familiarity with the tint or immediate memory for the colour of illumination. A consecutive sample of 1000 tint prescriptions was analysed numerically. For most prescriptions the variation in chromaticity with different types of lighting was not such as to remove all the potential benefit of the tint, as judged from a model of the effect of chromaticity on reading speed. The exceptions were the few tints that were weakly saturated or purple in colour. Across participants, reading speed was not consistently related to the scotopic energy, to the energy captured by any cone class, or to opponent colour processes. The reading was generally slowest with white light, and not with the colour complementary to the optimum. Explanations in terms of magnocellular deficits and cortical hyperexcitability are briefly discussed.
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Affiliation(s)
- Arnold J Wilkins
- Visual Perception Unit, Department of Psychology, University of Essex, Colchester CO4 3SQ, UK.
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Wilkins AJ, O'Callaghan MJ, Najman JM, Bor W, Williams GM, Shuttlewood G. Early childhood factors influencing health-related quality of life in adolescents at 13 years. J Paediatr Child Health 2004; 40:102-9. [PMID: 15009573 DOI: 10.1111/j.1440-1754.2004.00309.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To understand the relationship of health-related quality of life (HR-QOL) to early life experience. METHODOLOGY Eight thousand five hundred and fifty-six women enrolled in a prospective study at their first antenatal clinic visit. At 13 years, of 5345 women remaining, a consecutive sample of 901 mother/child pairs provided data on adolescent HR-QOL using the Child Health Questionnaire-Parent Report form (CHQ-PF50) and the Dartmouth COOP Functional Assessment Charts for Adolescents. The CHQ-PF50 yielded physical (PHS) and psychosocial (PSS) summary scores. We examined the relationship between health-related QOL and early childhood predictive variables. RESULTS PHS was related to gestation, maternal health symptoms in pregnancy, maternal anxiety at 6 months, child health and hours of childcare at 5 years (P < 0.05). PSS was related to maternal age at index visit, maternal attitude to pregnancy, maternal satisfaction with care giving and maternal depression at 6 months, and child health and behaviour problems at 5 years (internalizing and social/attentional/thought (SAT) domains) (P < 0.05). Findings from adolescent self-reports were similar. CONCLUSIONS This study has identified a number of early childhood determinants of adolescent HR-QOL. These findings add to evidence of the effects of early adversity on the developmental pathways of children and support the need for effective early intervention.
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Affiliation(s)
- A J Wilkins
- Department of Paediatrics and Child Health, The University of Queensland, St. Lucia, Queensland, Victoria, Australia.
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Abstract
Human epileptic photosensitivity has been studied in several ways. (a) Visual stimulation that resembles the stimulation normally responsible for seizures, such as that from televisions or videogames, both of which typically use cathode ray tubes in which the display is created in a flickering pattern. Such stimulation is often rendered yet more epileptogenic by programmes with content that also involves flashing or patterned material. (b) Elementary visual stimuli that enable inferences to be drawn concerning the physiological trigger mechanisms. The topographic distribution of epileptiform EEG activity in response to such stimuli has complemented this approach, leading to the inference that the trigger is cortical and requires sychronised mass action of neurons. (c) Stimuli that avoid paroxysmal EEG activity and permit an investigation of the subepileptic response to visual stimuli, using the evoked potential. This has revealed abnormalities in the cortical mechanisms that control the response to strong visual stimulation.
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Affiliation(s)
- Arnold J Wilkins
- Department of Psychology, University of Essex, Colchester, Essex, England
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Abstract
A double-masked randomized controlled study with cross-over design compared the effectiveness of precision ophthalmic tints in the prevention of headache in migraine sufferers. Seventeen patients chose the colour of light that optimally reduced perceptual distortion of text and maximized clarity and comfort. They were later given glasses with spectral filters providing optimal colour under conventional white lighting ('optimal' tint) or glasses that provided a slightly different colour ('control' tint). The tints were supplied in random order, each for 6 weeks, separated by an interval of at least 2 weeks with no tints. Headache diaries showed that the frequency of headaches was marginally lower when the 'optimal' tint was worn, compared with the 'control'. The trial extends to adults with migraine, the results of a previous double-masked study demonstrating, in children with reading difficulty, beneficial effects of precision tints in reducing symptom frequency. In the present study, however, the effects are suggestive rather than conclusive.
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Affiliation(s)
- A J Wilkins
- Visual Perception Unit, University of Essex, Colchester, and Institute of Optometry, London, UK
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Abstract
BACKGROUND Visual acuity, typically measured by the ability to name letters at a distance, is poorer when letters are small and closely spaced. It has been suggested that reading can be affected by letter size and spacing. AIM To determine the effect of text size and spacing on the ability to read at a distance, with a view to helping with the design of text in children's 'Big Books'. SAMPLE The visual acuity of 200 children aged between 6 and 12 was measured. A subset of 66 children was given further reading tests. METHOD From a viewing distance of 3m children were required (1) to identify words and (2) to read passages of text rapidly. A repeated measures design was used to compare the effects of different size and spacing of text on performance of the two tasks. RESULTS Performance improved when the spacing of words and size of letters was greater than is typical in 'Big Books'. For a given letter density, increasing the spacing improved performance more than increasing the letter size. CONCLUSION The text in children's books could be made easier to read by expanding the spacing between words and also by increasing the size of the print. The maximum viewing distance should be reduced from 15ft (4.6m) to 10ft (3.0m).
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Affiliation(s)
- Laura E Hughes
- Visual Perception Unit, Department of Psychology, University of Essex, UK
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Abstract
Optometrists frequently encounter patients with migraine and patients and practitioners sometimes suspect that visual stimuli or visual anomalies trigger headaches. There is a lack of evidence-based research on the issue, however. Some patients with migraine may be hypersensitive to visual stimuli, and it has been suggested that individually prescribed coloured filters might be an effective treatment to reduce symptoms from such stimuli. A recent randomised controlled trial showed such a treatment to be effective and the present paper reports on the optometric characteristics of the patients in this study. Twenty-one patients with neurologically diagnosed migraine were compared with 11 controls. No significant differences were found between the two groups with respect to refractive error, ocular pathology, colour vision, contrast sensitivity, accommodative function, strabismus and hyperphoria. The migraine group tended to be a little more exophoric, but by most criteria they were able to compensate for their exophoria as well as the control group. The migraine group were more prone to pattern glare than the controls (p = 0.004). The effects of precision tinted and control tinted lenses were investigated. The only variable to show a consistent and marked improvement with tinted lenses was pattern glare. The most likely mechanism for the benefit from individually prescribed coloured filters in migraine is the alleviation of cortical hyperexcitability (Wilkins et al. 1994) and associated pattern glare.
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Bouldoukian J, Wilkins AJ, Evans BJW. Randomised controlled trial of the effect of coloured overlays on the rate of reading of people with specific learning difficulties. Ophthalmic Physiol Opt 2002; 22:55-60. [PMID: 11829008 DOI: 10.1046/j.1475-1313.2002.00002.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A randomised controlled trial has demonstrated that, for selected children with reading difficulties, individually prescribed coloured filters reduce symptoms of asthenopia. In the present study, we investigate the effect of individually prescribed coloured overlays on the rate of reading. Subjects were 33 children and adults who: had consulted a specific learning difficulties clinic; had received treatment to normalise any conventional optometric and orthoptic anomalies; and subsequently reported symptomatic relief from coloured filters. These subjects carried out the Wilkins Rate of Reading Test (which assesses visual rather than linguistic factors) under two conditions: with their chosen coloured overlay and with a control filter. Steps were taken to ensure that a strong placebo effect was associated with the control overlay and, when asked which they preferred, subjects were not significantly more likely to prefer their coloured overlay than the control filter (p=0.11). Nonetheless, the rate of reading was significantly faster with the coloured overlay than with the control (p=0.0019). Further analyses support the conclusion that individually prescribed coloured filters can improve reading performance for reasons that cannot be solely attributed to conventional optometric factors or to placebo effects.
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Abstract
We determined the effect upon accommodative responses of tinted lenses prescribed for the relief of visual discomfort in a group of five long term lens wearers. Static and dynamic responses were measured under four viewing conditions (1) prescribed tinted lens (2) neutral density filter (3) tinted lens of complementary colour and (4) no absorptive lens. While similarity and normality of the mean stimulus-response functions between the four viewing conditions were evident, the low frequency component of the accommodation microfluctuations was significantly greater while viewing the target in the 'no lens' viewing condition. These increases in the low frequency components (LFC) of the accommodation may be a subtle indicator of visual stress in these patients. Colour specificity is not supported by this finding.
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Affiliation(s)
- A J Simmers
- Department of Academic Ophthalmology, Imperial College of Science, Technology and Medicine, Western Eye Hospital, London, UK.
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Simmers AJ, Bex PJ, Smith FK, Wilkins AJ. Spatiotemporal visual function in tinted lens wearers. Invest Ophthalmol Vis Sci 2001; 42:879-84. [PMID: 11222554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
PURPOSE Tinted lenses have been widely publicized as a successful new treatment for reading disorders and visual stress in children. The present study was designed to investigate a variety of visual deficits reported by children who experience high levels of visual stress and perceptual distortions when reading (Meares-Irlen syndrome; MIS) and to assess the improvements in visual comfort they report when tinted lenses are worn. METHODS Twenty children (13.1 +/- 0.9 years of age) were recruited who had successfully worn tinted lenses for at least 6 months and were compared with an age-matched control group (12.6 +/- 2.2 years of age) of 21 children who were not lens wearers. A range of psychophysical tasks was adapted to identify specific anomalous visual perceptions. Spatiotemporal contrast sensitivity and contrast increment thresholds were used to investigate subjective reports of dazzle and hypercontrast, and a minimum motion perception (D(min)) and a motion-coherence task were used to assess subjective reports of visual instability and motion. RESULTS In all viewing conditions (with versus without lens), no selective functional visual loss was demonstrated with any of the tasks used. Psychometric functions also revealed no significant difference between subject groups (control versus MIS). CONCLUSIONS Under thorough psychophysical investigation, these results revealed no significant difference in visual function between subject group, and this finding is consistent with the absence of any effect of the tinted lenses in the group with MIS.
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Affiliation(s)
- A J Simmers
- Imperial College School of Medicine, Department of Academic Ophthalmology, The Western Eye Hospital, 171 Marylebone Road, London NW1 5 YE, UK.
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Wilkins AJ, Baker A, Amin D, Smith S, Bradford J, Zaiwalla Z, Besag FM, Binnie CD, Fish D. Treatment of photosensitive epilepsy using coloured glasses. Seizure 1999; 8:444-9. [PMID: 10627405 DOI: 10.1053/seiz.1999.0337] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
A recently introduced optometric technique, colorimetry, enables the perceptual effects of ophthalmic tints to be evaluated subjectively, optimized, and then prescribed in tinted spectacles. The new technique is beneficial in reducing visual stress in patients with dyslexia and migraine. We describe an open trial designed to ascertain: (1) whether the colorimetry assessment, as it is now given, is safe for the investigation of photosensitive patients in optometry clinics where colorimetry equipment is most readily available, but where EEG control is not practical; (2) what proportion of patients with photosensitive epilepsy is likely to benefit to the extent already described in individual cases; (3) whether a tint selected by colorimetry could be shown to reduce the incidence of paroxysmal epileptiform EEG activity in response to flicker and patterns, thereby validating the subjective methods and corroborating the reported seizure reduction. Twenty-four females and nine males (aged 12-43 years) took part. All the patients had suffered visually-provoked seizures, had exhibited a photoparoxysmal response on at least one previous EEG recording, and had received a diagnosis of photosensitive epilepsy. Twenty-two were currently experiencing seizures. A further EEG was recorded in all except seven cases: a routine resting record, followed by hyperventilation. Colorimetry was performed after hyperventilation and before photic stimulation. Twenty-three (70%) reported beneficial effects during colorimetry and were prescribed glasses. There was a preponderance of lenses with a rose or purple colour, in contrast to patients with dyslexia. Seventeen of the 23 patients were available at follow-up, an average of 2.4 years later. Thirteen (57%) reported benefits, and said they were still using the lenses. In six of the 13 the benefits were pronounced, including a reduction of dizziness from fluorescent lighting, elimination of aura when using computer screens etc. Only in three cases was there a reduction in seizures that could reasonably be attributed to the use of lenses; in two of these cases no medications were prescribed, and in the third the medications remained unchanged for four years, two before and two after the introduction of the glasses. In an additional four cases a reduction in seizures was observed but medication had been changed. There was a modest reduction in EEG photosensitivity with the coloured lenses but also to an equivalent or lesser extent with grey in all of the eight patients examined in this way. One patient had seizures during colorimetry, but the seizures were not accompanied by scalp EEG changes.
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Affiliation(s)
- A J Wilkins
- Visual Perception Unit, University of Essex, UK
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Evans BJ, Patel R, Wilkins AJ, Lightstone A, Eperjesi F, Speedwell L, Duffy J. A review of the management of 323 consecutive patients seen in a specific learning difficulties clinic. Ophthalmic Physiol Opt 1999; 19:454-66. [PMID: 10768028 DOI: 10.1046/j.1475-1313.1999.00465.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Visual correlates of specific learning difficulties (SpLD) include: binocular instability, low amplitude of accommodation, and Meares-Irlen Syndrome. Meares-Irlen Syndrome describes asthenopia and perceptual distortions which are alleviated by using individually prescribed coloured filters. Data from 323 consecutive patients seen over a 15 month period in an optometric clinic specialising in SpLD are reviewed. Visual symptoms and headaches were common. 48% of patients were given a conventional optometric intervention (spectacles, orthoptic exercises) and 50% were issued with coloured filters, usually for a trial period. 40% of those who were given orthoptic exercises were later issued with coloured overlays. 32% of those who were issued with coloured overlays were ultimately prescribed Precision Tinted lenses. Approximately half the sample were telephoned more than a year after the last clinical appointment. More than 70% of those who were prescribed Precision Tints were still wearing them daily, and results for this intervention compared favourably with data for non-tinted spectacles. The data suggest that many people with SpLD need optometric care and that the optometrist needs to be skilled in orthoptic techniques and cognisant of recent research on coloured filters.
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Binnie CD, Wilkins AJ. Visually induced seizures not caused by flicker (intermittent light stimulation). Adv Neurol 1998; 75:123-38. [PMID: 9385418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- C D Binnie
- Institute of Epileptology, King's College, London, United Kingdom
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