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Frontiers in Human Neuroscience 2015Recent studies have revealed that human position sense relies on a massively distorted representation of hand size and shape. By comparing the judged location of...
Recent studies have revealed that human position sense relies on a massively distorted representation of hand size and shape. By comparing the judged location of landmarks on an occluded hand, Longo and Haggard (2010) constructed implicit perceptual maps of represented hand structure, showing large underestimation of finger length and overestimation of hand width. Here, we investigated the contribution of two potential sources of distortions to such effects: perceptual distortions reflecting spatial warping of the representation of bodily tissue itself, perhaps reflecting distortions of somatotopic cortical maps, and conceptual distortions reflecting mistaken beliefs about the locations of different landmarks within the body. In Experiment 1 we compared distorted hand maps to a task in which participants explicitly judged the location of their knuckles in a hand silhouette. The results revealed the conceptual distortions are responsible for at least part of the underestimation of finger length, but cannot explain overestimation of hand width. Experiment 2 compared distortions of the participant's own hand based on position sense with a prosthetic hand based on visual memory. Underestimation of finger length was found for both hands, providing further evidence that it reflects a conceptual distortion. In contrast, overestimation of hand width was specific to representation of the participant's own hand, confirming it reflects a perceptual distortion. Together, these results suggest that distorted body representations do not reflect a single underlying cause. Rather, both perceptual and conceptual distortions contribute to the overall configuration of the hand representation.
PubMed: 26733842
DOI: 10.3389/fnhum.2015.00656 -
Optics Express Jul 2022Single image dehazing is a challenging task because of the hue and brightness distortion problems due to the atmospheric scattering. These problems limit the perceptual...
Single image dehazing is a challenging task because of the hue and brightness distortion problems due to the atmospheric scattering. These problems limit the perceptual fidelity, as well as information integrity, of a given image. In this paper, we propose an image dehazing method based on the optical neural networks dehazing by simulating optical diffraction. The algorithm is trained from a large number of hazy images and their corresponding clean images. The experimental results demonstrate that the proposed method has reached an advanced level in both PSNR and SSIM dehazing performance indicators, and the amount of calculation is less than most artificial neural networks.
PubMed: 36236995
DOI: 10.1364/OE.458610 -
CA: a Cancer Journal For Clinicians 2007Cancer risk perceptions are a key predictor of risk-reduction practices, health behaviors, and processing of cancer information. Nevertheless, patients and the general... (Review)
Review
Cancer risk perceptions are a key predictor of risk-reduction practices, health behaviors, and processing of cancer information. Nevertheless, patients and the general public (as well as health care providers) exhibit a number of errors and biases in the way they think about risk, such that their risk perceptions and decisions deviate greatly from those prescribed by normative decision models and by experts in risk assessment. For example, people are more likely to engage in screening behaviors such as mammography when faced with loss-based messages than gain-framed messages, and they often ignore the base rate of a given disease when assessing their own risk of obtaining this disease. In this article, we review many of the psychological processes that underlie risk perception and discuss how these processes lead to such deviations. Among these processes are difficulties with use of numerical information (innumeracy), cognitive processes (eg, use of time-saving heuristics), motivational factors (eg, loss and regret aversion), and emotion. We conclude with suggestions for future research in the area, as well as implications for improving the elicitation and communication of personal cancer risk.
Topics: Affect; Attitude to Health; Emotions; Health Behavior; Health Knowledge, Attitudes, Practice; Humans; Mass Screening; Neoplasms; Perceptual Distortion; Persuasive Communication; Risk Assessment; Risk Factors; Risk-Taking
PubMed: 17507441
DOI: 10.3322/canjclin.57.3.147 -
Investigative Ophthalmology & Visual... Aug 2015Develop a paradigm to map binocular perceptual visual distortions in adult amblyopes and visually normal controls, measure their stability over time, and determine the...
PURPOSE
Develop a paradigm to map binocular perceptual visual distortions in adult amblyopes and visually normal controls, measure their stability over time, and determine the relationship between strength of binocular single vision and distortion magnitude.
METHODS
Perceptual visual distortions were measured in 24 strabismic, anisometropic, or microtropic amblyopes (interocular acuity difference ≥ 0.200 logMAR or history of amblyopia treatment) and 10 controls (mean age 27.13 ± 10.20 years). The task was mouse-based target alignment on a stereoscopic liquid crystal display monitor, measured binocularly five times during viewing dichoptically through active shutter glasses, amblyopic eye viewing cross-hairs, fellow eye viewing single target dots (16 locations within central 5°), and five times nondichoptically, with all stimuli visible to either eye. Measurements were repeated over time (1 week, 1 month) in eight amblyopic subjects, evaluating test-retest reliability. Measurements were also correlated against logMAR visual acuity, horizontal prism motor fusion range, Frisby/Preschool Randot stereoacuity, and heterophoria/heterotropia prism cover test measurement.
RESULTS
Sixty-seven percent (16/24) of amblyopes had significant perceptual visual distortions under dichoptic viewing conditions compared to nondichoptic viewing conditions and dichoptic control group performance. Distortions correlated with the strength of motor fusion (r = -0.417, P = 0.043) and log stereoacuity (r = 0.492, P = 0.015), as well as near angle of heterotropic/heterophoric deviation (r = 0.740, P < 0.001), and, marginally, amblyopia depth (r = 0.405, P = 0.049). Global distortion index (GDI, mean displacement) remained, overall, consistent over time (median change in GDI between baseline and 1 week = -0.03°, 1 month = -0.08°; x-axis Z = 4.4256, P < 0.001; y-axis Z = 5.0547, P < 0.001).
CONCLUSIONS
Perceptual visual distortions are stable over time and associated with poorer binocular function, greater amblyopia depth, and larger angles of ocular deviation. Assessment of distortions may be relevant for recent perceptual learning paradigms specifically targeting binocular vision.
Topics: Adolescent; Adult; Amblyopia; Female; Follow-Up Studies; Humans; Male; Middle Aged; Perceptual Distortion; Reproducibility of Results; Time Factors; Vision, Binocular; Visual Acuity; Visual Perception; Young Adult
PubMed: 26284559
DOI: 10.1167/iovs.15-17071 -
Clinical & Experimental Optometry Jul 2008Optometrists will frequently see patients, who may have a diagnosis or a suspected diagnosis of dyslexia (specific reading disorder) and will need to manage and counsel... (Review)
Review
Optometrists will frequently see patients, who may have a diagnosis or a suspected diagnosis of dyslexia (specific reading disorder) and will need to manage and counsel such patients. There are many propounded theories on the cause(s) of dyslexia. Although most professionals in this area consider that dyslexia is chiefly a linguistic disorder, the possibility of a visual component is contentious. This article is a selective review of two commonly discussed theories that suggest a visual component in dyslexia; the magnocellular deficit theory and Meares-Irlen syndrome.
Topics: Asthenopia; Dyslexia; Flicker Fusion; Humans; Optometry; Perceptual Disorders; Perceptual Distortion; Professional Role; Vision, Ocular; Visual Pathways
PubMed: 18430036
DOI: 10.1111/j.1444-0938.2008.00277.x -
Journal of Clinical Medicine Dec 2019We combined virtual reality and multisensory bodily illusion with the aim to characterize and reduce the perceptual (body overestimation) and the cognitive-emotional...
We combined virtual reality and multisensory bodily illusion with the aim to characterize and reduce the perceptual (body overestimation) and the cognitive-emotional (body dissatisfaction) components of body image distortion (BID) in anorexia nervosa (AN). For each participant (20 anorexics, 20 healthy controls) we built personalized avatars that reproduced their own body size, shape, and verisimilar increases and losses of their original weight. Body overestimation and dissatisfaction were measured by asking participants to choose the avatar that best resembled their real and ideal body. Results show higher body dissatisfaction in AN, caused by the desire of a thinner body, and no body-size overestimation. Interpersonal multisensory stimulation (IMS) was then applied on the avatar reproducing participant's perceived body, and on the two avatars which reproduced increases and losses of 15% of it, all presented with a first-person perspective (1PP). Embodiment was stronger after synchronous IMS in both groups, but did not reduce BID in participants with AN. Interestingly, anorexics reported more negative emotions after embodying the fattest avatar, which scaled with symptoms severity. Overall, our findings suggest that the cognitive-emotional, more than the perceptual component of BID is severely altered in AN and that perspective (1PP vs. 3PP) from which a body is evaluated may play a crucial role. Future research and clinical trials might take advantage of virtual reality to reduce the emotional distress related to body dissatisfaction.
PubMed: 31906009
DOI: 10.3390/jcm9010098 -
Trends in Cognitive Sciences Jan 2005We are often aware of the content of distracting sound, although typically remain unaware of the processes by which that sound is disruptive. Disruption can occur even... (Review)
Review
We are often aware of the content of distracting sound, although typically remain unaware of the processes by which that sound is disruptive. Disruption can occur even when the sound is ignored and unrelated to the task being performed. In a recent major development, Gisselgård et al. have used positron emission tomography to reveal how distracting sounds recruit the involvement of dorsolateral prefrontal cortex.
Topics: Auditory Perception; Brain Mapping; Cognitive Science; Humans; Neurosciences; Perceptual Distortion; Positron-Emission Tomography; Prefrontal Cortex
PubMed: 15639433
DOI: 10.1016/j.tics.2004.11.002 -
Zeitschrift Fur Kinder- Und... Jan 2014Body image is multifaceted and incorporates perceptual, affective, and cognitive components as well as behavioral features. Only few studies have examined the character... (Comparative Study)
Comparative Study Review
Body image is multifaceted and incorporates perceptual, affective, and cognitive components as well as behavioral features. Only few studies have examined the character of body-image disturbance in children/adolescents with eating disorders. It is unknown whether body-image disturbances in children/adolescent with eating disturbances are comparable to those of adult patients with eating disorders. Body-image disturbance might differ quantitatively and qualitatively according to the cognitive developmental status and the age of the individual. This paper provides an overview of the current evidence for body-image disturbance in children/adolescents with eating disorders, and how they compare with those adults with eating disorders. Current evidence indicates that older adolescent patients show similar deficits as adult patients with eating disorders, in particular for the attitudinal body-image component. However, evidence for a perceptual body-image disturbance in adolescent patients, in particular anorexia nervosa, is not conclusive. Reliable statements for childhood can hardly be made because clinical studies are not available. Investigations of body-image disturbance in children have focused on the predictive value for eating disorders. Limitations of the current evidence are discussed, and future directions for research and therapy are indicated.
Topics: Adolescent; Adult; Age Factors; Anorexia Nervosa; Body Dysmorphic Disorders; Body Size; Child; Cognition Disorders; Feeding and Eating Disorders; Female; Humans; Perceptual Distortion
PubMed: 24365963
DOI: 10.1024/1422-4917/a000269 -
Scientific Reports Jul 2021Mechanoreceptors on the skin are heterogeneously distributed, and the sampling of neural signals in the brain can vary depending on the part of the body. Therefore, it... (Comparative Study)
Comparative Study
Mechanoreceptors on the skin are heterogeneously distributed, and the sampling of neural signals in the brain can vary depending on the part of the body. Therefore, it can be challenging for the brain to consistently represent stimuli applied to different body sites. Here, we report an example of a regional perceptual distortion of the tactile space. We used a piezoelectric braille display to examine shape perception on the volar surface of the arm and to compare it to that on the palm. We found that the orientation of perceived stimuli on the arm was distorted in certain areas. In particular, an inwardly-inclined line shape was perceived as being more inwardly-inclined than it actually was. On the other hand, an outwardly-inclined line was perceived accurately. When the same stimuli were applied to the palm, this anisotropic bias was not observed. We also found that changing the posture of the arm changed the angle at which this anisotropic distortion occurred, suggesting the influence of the skin frame of reference on this illusion. This study showed a clear example of how the representation of even simple stimuli is complexly distinct when the stimuli are applied to different body sites.
Topics: Adult; Anisotropy; Arm; Female; Hand; Humans; Illusions; Male; Mechanoreceptors; Middle Aged; Orientation, Spatial; Perception; Perceptual Distortion; Physical Stimulation; Posture; Space Perception; Touch; Touch Perception; Young Adult
PubMed: 34272414
DOI: 10.1038/s41598-021-93959-2 -
Behaviour Research and Therapy May 1992In 21 restrained and 20 unrestrained eaters body size perception was measured using the video distortion technique (VDT), the image marking procedure (IMP) and the... (Review)
Review
In 21 restrained and 20 unrestrained eaters body size perception was measured using the video distortion technique (VDT), the image marking procedure (IMP) and the kinesthetic size estimating apparatus (KSEA). Body satisfaction was assessed by questionnaires (Body Shape Questionnaire, Dieting scale of the Eating Attitudes Test). Restrained eaters showed no systematic over- or underestimation of the body size but less perceptual accuracy (in VDT and KSEA). Furthermore, they were clearly more dissatisfied with their bodies than unrestrained eaters. Both findings were unrelated to each other. In both groups depressive mood or thoughts seemed to be associated with body dissatisfaction but not with body size misperception. Objective body measures (body mass index, body fat content) were not related to either body size perception or body satisfaction. The findings suggest that a perceptual uncertainty in regard to body size (either for visual or for somatosensory aspects) has already developed in restrained eaters, which may constitute a predisposition for more overt forms of body size misperception as found in eating disorder patients.
Topics: Behavior Therapy; Body Constitution; Body Image; Body Mass Index; Energy Intake; Feeding Behavior; Feeding and Eating Disorders; Female; Humans; Male; Perception; Perceptual Distortion; Surveys and Questionnaires
PubMed: 1586361
DOI: 10.1016/0005-7967(92)90070-w