Search results for "Psychophysic"

showing 10 items of 97 documents

Changes in visual function and retinal structure in the progression of Alzheimer's disease

2019

Background Alzheimer's Disease (AD) can cause degeneration in the retina and optic nerve either directly, as a result of amyloid beta deposits, or secondarily, as a result of the degradation of the visual cortex. These effects raise the possibility that tracking ophthalmologic changes in the retina can be used to assess neurodegeneration in AD. This study aimed to detect retinal changes and associated functional changes in three groups of patients consisting of AD patients with mild disease, AD patients with moderate disease and healthy controls by using non-invasive psychophysical ophthalmological tests and optical coherence tomography (OCT). Methods We included 39 patients with mild AD, 2…

Visual acuitygenetic structuresVisionVisual AcuitySocial SciencesAlzheimer's DiseaseDiagnostic Radiologychemistry.chemical_compound0302 clinical medicineMedicine and Health SciencesContrast (vision)PsychologyTécnicas de la imagenTomographymedia_commonCognitive ImpairmentMultidisciplinaryCognitive NeurologyRadiology and ImagingQRNeurodegenerative Diseasesmedicine.anatomical_structureNeurologyOptic nerveDisease ProgressionMedicineOftalmologíaSensory Perceptionmedicine.symptomAnatomyColor PerceptionTomography Optical CoherenceResearch Articlemedicine.medical_specialtyImaging TechniquesSciencemedia_common.quotation_subjectOcular AnatomyCognitive NeuroscienceResearch and Analysis MethodsRetinaContrast Sensitivity03 medical and health sciencesAlzheimer DiseaseOcular SystemDiagnostic MedicineOphthalmologyMental Health and PsychiatrymedicinePsychophysicsHumansOuter nuclear layerGanglion cell layerVision OcularRetinaColor Visionbusiness.industryBiology and Life SciencesRetinaleye diseasesGeriatríachemistry030221 ophthalmology & optometryEyesCognitive ScienceDementiaChoroidsense organsbusinessHead030217 neurology & neurosurgeryNeuroscience
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Psychophysical response to electrocutaneous stimulation.

1984

A method is presented to determine a reliable stimulus-sensation relationship particularly suitable for electrocutaneous stimulation. An experimental intensity-discrimination curve was obtained through simple psychophysical comparison tasks, and sensory response was inferred from integration of a JND's density function. The psychophysical response resembles a power law, although departures cannot be described in terms of a unique exponent. An estimate of binary information capacity per electrode is also given as a feature of a stimulation procedure that preserves a low value of the size-intensity product.

business.industryBiomedical EngineeringSensationStimulation procedurePattern recognitionStimulationSensory systemProbability density functionElectrocutaneous stimulationPower lawElectric StimulationBinary informationDiscrimination PsychologicalPsychophysicsHumansArtificial intelligenceEvoked potentialPsychologybusinessSkinIEEE transactions on bio-medical engineering
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Visual Cortex Performs a Sort of Non-linear ICA

2010

Here, the standard V1 cortex model optimized to reproduce image distortion psychophysics is shown to have nice statistical properties, e.g. approximate factorization of the PDF of natural images. These results confirm the efficient encoding hypothesis that aims to explain the organization of biological sensors by information theory arguments.

business.industrySpeech recognitionPattern recognitionMutual informationInformation theoryVisual cortexmedicine.anatomical_structureFactorizationEncoding (memory)DistortionmedicinePsychophysicssortComputer visionArtificial intelligencebusinesshealth care economics and organizationsMathematics
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Sport and Quality of Life

2022

Negli ultimi trent’anni lo sport ha assunto un significato molto rilevante nella vita delle persone e, seppure con notevoli differenze, sia nei paesi a sviluppo economico avanzato, sia in quelli in via di sviluppo. A livello individuale, esso ha costituito un’area di investimento identitario quando ha assunto la forma di sport spettacolo del quale fruire, alimentando la pratica del tifo e il fandom o costituendo il modello di uno stile di vita vincente; ma anche quando ha assunto la forma di pratica del tempo libero attraverso la quale tenersi in forma, facendo crescere, in questo caso, la diffusione di una cultura della salute e del benessere. Si tratta di due modalità di approcciare al co…

but also when he took the form of free time practice through which to keep fit making grow in this case the diffusion of a culture of health and well-being. These are two ways of approaching the consumption of sports by spectators and actorIn the last thirty years sport has taken on a very significant meaning in people's lives and albeit with considerable differences both in advanced economic development countries and in developing countries. On an individual level it constituted an area of identity investment when it assumed the shape of “sport spectacle” to be enjoyed fueling the practice of cheering and fandom or constituting the model of a winning lifestyleand the two ways of use can be strongly related to the perception and assessment of the quality of life. The “semantic universes” which however connote sport and “free time sports” have often appeared polarized. Commercial sport and sports professionalism are intertwined with the institutions of economics politics and culture which above all stress its “spectacularity” in order to capture first and foremost the audience. But also the sport of leisure time is intertwined with the actions of the institutions of economics politics and culture with the difference that these stress above all its “healthy value” aimed at the “healthy and rational” investment of time in an activity which improves the quality of life in the short medium and long period. This polarization between the consumption of sport entertainment - commercial sport - and the consumption of sport as a leisure activity - sport for all - has become increasingly interconnected precisely because of the increased collective identity demand via sport. In other words we have witnessed the spread of shape of sports entertainment that recall the importance of sports for psychophysical well-being for integration and social participation for the reduction of social inequalities ethnic and cultural differences and in which the importance assumed was weakened in the show from agonism from competition from the physical confrontation between two contenders or two teams. A sport in which we act with competitors as well as against competitors. And on the other hand we have gradually witnessed the spectacularization of sports in our free time to the point that the sharing of the results obtained through the declination of a competitive spirit that presents itself as directed no longer against other contenders but against its own performance limits it has become the way in which each person makes part of his or her own life spectacular the one he often considers most authentic. The aim of this work is to describe how the intertwining between the commercial/professional dimension of the sports show and the playful/recreational dimension of sports practice are fueled by a demand and an offer of social identity that characterizes these two “semantic universes”.Settore SPS/07 - Sociologia Generale
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Psychophysical burden and lack of support : Reasons for care workers’ intentions to leave their work in the Nordic countries

2021

Long-term care of older adults is currently suffering from a shortage of trained personnel and high turnover rates. Care work is poorly paid, demanding, increasingly time-bound and both mentally and physically burdensome. In this study, we examined the individual, organisational and economic factors that predict professional care workers’ intentions to leave their current employment, using the NORDCARE survey data (2015, N = 3801) collected in Denmark, Finland, Norway and Sweden. The respondents were mainly practical and assistant nurses. The analysis showed that the predictors of intentions to leave were similar in the four countries. The most consistent organisational predictors of leavin…

care worktyövoiman kysyntäSociology and Political Sciencetyöhyvinvointipitkäaikaishoitotyövoimantarveleaving intentionslong- term carevanhustenhuoltopsychophysical burden03 medical and health sciences0302 clinical medicineNursing050602 political science & public administrationhoiva-ala030212 general & internal medicinetyöelämäolder adults05 social sciencestyövoiman vaihtuvuus0506 political scienceterveydenhuoltohenkilöstöpsykofysiologiaLong-term careWork (electrical)Care workers8. Economic growthhoitohenkilöstölähihoitajatperushoitajathenkilöstöCare workvanhustenhuoltolaitoksetPsychologytyöpaikan vaihtoikääntyneethoitotyö
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Color induction via non-opponent lateral interactions in the human retina

1992

Retinal connections causing colors in Benham's top (pattern induced flicker colors, PIFCs) are investigated by psychophysical experiments. PIFCs are still seen when stimuli to different cones are demodulated selectively, indicating the involvement of non-opponent channels. PIFCs also occur on retinal areas next to those affected by modulated stimuli; further, both monochromat and dark-adapted trichromats perceive PIFCs which are achromatic. These additional findings point to horizontal cells as neuronal mediators of modulated excitation leading to PIFCs. The unspecifity of the postulated connection with respect to cone types agrees with anatomic findings of Boycott, B. B., Hopkins, J. M. an…

genetic structuresColor visionModels NeurologicalRetinaBenham's topFlicker Fusionchemistry.chemical_compoundOpticsPsychophysicsmedicinePsychophysicsHumansPhotoreceptor CellsNeuronsRetinabusiness.industryOptical illusionFlickerTrichromacyRetinalSensory SystemsOphthalmologymedicine.anatomical_structurePattern Recognition VisualchemistrySpectrophotometrybusinessPsychologyNeuroscienceColor PerceptionMathematicsVision Research
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Color stimuli perception in presence of light scattering.

2006

Perception of different color contrast stimuli was studied in the presence of light scattering: in a fog chamber in Clermont-Ferrand and in laboratory conditions where light scattering of similar levels was obtained, using different light scattering eye occluders. Blue (shortest wavelength) light is scattered in fog to the greatest extent, causing deterioration of vision quality especially for the monochromatic blue stimuli. However, for the color stimuli presented on a white background, visual acuity in fog for blue Landolt-C optotypes was higher than for red and green optotypes on the white background. The luminance of color Landolt-C optotypes presented on a LCD screen was chosen corresp…

genetic structuresPhysiologyVisual AcuityColorLuminanceRed ColorLight scatteringlaw.inventionContrast SensitivityOpticslawPsychophysicsHumansChromatic scalePhysicsColor Perception Testsbusiness.industryScatteringSensory SystemsAchromatic lensSensory ThresholdsRGB color modelMonochromatic colorbusinessColor PerceptionPhotic StimulationVisual neuroscience
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100 Years of Benham's Top in Colour Science

1995

For 100 years Benham's top has been a popular device demonstrating pattern-induced flicker colours (PIFCs). Results of early and recent investigations on PIFCs are reported and show that the phenomenon originates in phase-sensitive lateral interactions of modulated neural activity in the retina followed by additional spatial interactions in the visual cortex behind the locus of binocular fusion. Colour matches with normal colour stimuli indicate that S/(M + L) opponent neurons are involved. Dichromats do not find matching stimuli for all PIFCs. PIFCs may become useful in medical diagnosis. The phenomenon is interpreted as a side effect of a neural mechanism providing colour constancy under…

genetic structuresmedia_common.quotation_subjectMotion PerceptionIllusionExperimental and Cognitive PsychologyStimulus (physiology)Retina050105 experimental psychologyBenham's topFlicker Fusion03 medical and health sciencesNeural activity0302 clinical medicineRetinal Rod Photoreceptor CellsArtificial IntelligenceOrientationPsychophysicsmedicinePsychophysicsHumansVisual Pathways0501 psychology and cognitive sciencesVisual Cortexmedia_commonNeuronsRetinaCommunicationOptical Illusionsbusiness.industryFlicker05 social sciencesSensory SystemsOphthalmologymedicine.anatomical_structureVisual cortexRetinal Cone Photoreceptor CellsbusinessPsychologyNeuroscienceColor Perception030217 neurology & neurosurgeryPerception
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Spatio-temporal Contrast Sensitivity in the Cardinal Directions of the Colour Space. A Review

2010

AbstractWe review the psychophysics of the spatio-temporal contrast sensitivity in the cardinal directions of the colour space and their correlation with those neural characteristics of the visual system that limit the ability to perform contrast detection or pattern-resolution tasks. We focus our attention particularly on the influence of luminance level, spatial extent and spatial location of the stimuli - factors that determine the characteristics of the physiological mechanisms underlying detection. Optical factors do obviously play a role, but we will refer to them only briefly. Contrast sensitivity measurements are often used in clinical practice as a method to detect, at their early …

genetic structuresmedia_common.quotation_subjectReviewVisual systempatrones espacio-temporalesLuminanceCorrelationcolour spacecaminos visualeslcsh:OphthalmologyPsychophysicslcsh:QC350-467Contrast (vision)direcciones cardinalesSensitivity (control systems)media_commoncontrast sensitivitybusiness.industrycardinal directionsPattern recognitionvisual pathwayssensibilidad al contrastelcsh:RE1-994spatio-temporal patternsespacio de colorArtificial intelligencebusinessFocus (optics)Psychologylcsh:Optics. LightOptometryCardinal directionJournal of Optometry
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Parallel Adaptation to Spatially Distinct Distortions

2020

Optical distortions as a visual disturbance are inherent in many optical devices such as spectacles or virtual reality headsets. In such devices, distortions vary spatially across the visual field. In progressive addition lenses, for example, the left and right regions of the lens skew the peripheral parts of the wearers visual field in opposing directions. The human visual system adapts to homogeneous distortions and the respective aftereffects are transferred to non-retinotopic locations. This study investigates simultaneous adaptation to two opposing distortions at different retinotopic locations. Two oppositely skewed natural image sequences were presented to 10 subjects as adaptation s…

lcsh:Psychologypsychophysicsnatural sceneslcsh:BF1-990visual systemdistortionsvisual adaptationmotion aftereffectFrontiers in Psychology
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