Search results for " visual"

Subtle retinal pathology in amyotrophic lateral sclerosis

2014

Amyotrophic lateral sclerosis (ALS) is characterized by neuro-ophthalmological abnormalities beyond disturbed oculomotor control such as decreased visual acuity and disturbed visual evoked potentials. Here we report retinal alterations in a cohort of 24 patients with clinically definite (n = 20) or probable (n = 4) ALS as compared to matched controls. High-resolution spectral domain optical coherence tomography with retinal segmentation revealed a subtle reduction in the macular thickness and the retinal nerve fiber layer (RNFL) as well as a marked thinning of the inner nuclear layer (INL). Our data indicate an unprecedented retinal damage pattern and suggest neurodegeneration beyond the mo…

Vizuālizpratne mākslas muzeju pedagoģijā vidusskolai

2018

Maģistra darba “Vizuālizpratne muzeju pedagoģijā vidusskolai” pētījuma problēma ir vienotu kvalitātes kritēriju trūkums kultūras mantojuma apguves sekmēšanā, kad, līdzās skolai ir muzejpedagoģija. Šādā situācijā tiek veidoti vizuālizpratnes[ Vizuālizpratnes koncepts izstrādāts pēc Eiropas Vienotās valodu prasmes noteikšanas sistēmas (angl. Common European Framework of Reference; CEFR) parauga.] treniņi, ar nolūku strukturizēt mākslas izglītību. Pētījuma mērķis ir izstrādāt un aprobēt muzejpedagoģijas metodes, kas aktualizētu mākslas muzeja iespējas paaugstināt vidusskolēnu. Pētāmā grupa ir vidusskolēni. Pētījuma dizains: gadījuma pētījums (angl. a case study) un tā sasniegšanai lietotās met…

A 3D reworking of the urban transformations of Palermo in recent history for a hypothesis of a "City Museum" based on digital visualizations

2021

The objective that drives this research is given by a multitude of information which, in addition to the contribution of technology, allows us to study, analyze, verify and remodel the sites, monuments and evolutions of the city through graphic processes of perspective restitution that start from the analysis of historical photos. The drawing methods, the digital graphic rendering and through the aid of geometric techniques, contribute to the reconstruction of projects and architectures that are now lost, this is possible thanks to the methods of perspective, axonometry and three-dimensional restitution. This remarkable photographic heritage belonging to Palermo, but also to any other city …

Fourier analysis of the stimuli for pattern-induced flicker colors.

1992

Pattern-induced flicker colors (PIFCs) were observed and color matched in rotating discs from which higher-harmonic Fourier components in the square-wave temporal luminance functions of a conventional black-and-white Benham disc had been removed. Since both reddish-brown and blue PIFCs were visible with purely sinusoidal stimuli they cannot result from differences in temporal stimulus shape or pattern and do not provide evidence for a temporal coding theory of color. Green PIFCs differed in that they did require the presence of additional harmonics. In a second experiment the luminance means upon which the sinusoidal PIFC stimuli were imposed were varied. The results show that color is dete…

2016

The wealth of sensory data coming from different modalities has opened numerous opportunities for data analysis. The data are of increasing volume, complexity and dimensionality, thus calling for new methodological innovations towards multimodal data processing. However, multimodal architectures must rely on models able to adapt to changes in the data distribution. Differences in the density functions can be due to changes in acquisition conditions (pose, illumination), sensors characteristics (number of channels, resolution) or different views (e.g. street level vs. aerial views of a same building). We call these different acquisition modes domains, and refer to the adaptation problem as d…

2013

The motion energy sensor has been shown to account for a wide range of physiological and psychophysical results in motion detection and discrimination studies. It has become established as the standard computational model for retinal movement sensing in the human visual system. Adaptation effects have been extensively studied in the psychophysical literature on motion perception, and play a crucial role in theoretical debates, but the current implementation of the energy sensor does not provide directly for modelling adaptation-induced changes in output. We describe an extension of the model to incorporate changes in output due to adaptation. The extended model first computes a space-time r…

Experimental multichannel recognition capability of polychromatic objects using optical correlators

1990

Polychromatic object recognition by multichannel correlation is experimentally achieved. Model objects whose shape changes with the wavelength of the illumination beam were used. Highpass matched filters were employed. The results confirm previous numerical simulations 1.

Red-green vs. blue-yellow spatio-temporal contrast sensitivity across the visual field

2011

We measured contrast sensitivity (CS) to sinusoidal spatio-temporal patterns isolating the red-green and blue-yellow mechanisms, at 21 locations in the visual field (including the fovea). These measurements complete the available data for the red-green mechanism at fovea and for both mechanisms outside fovea with non-stationary patterns. Chromatic detection surfaces are low-pass at fovea and CS decreases with eccentricity at a rate that depends on the spatial and temporal frequencies. Our results confirm that, in general, sensitivities decrease with eccentricity at different rates for stationary red-green and blue-yellow patterns at each point of the spatio-temporal domain and that the chro…

General principles in motion vision: Color blindness of object motion depends on pattern velocity in honeybee and goldfish

2011

AbstractVisual systems can undergo striking adaptations to specific visual environments during evolution, but they can also be very “conservative.” This seems to be the case in motion vision, which is surprisingly similar in species as distant as honeybee and goldfish. In both visual systems, motion vision measured with the optomotor response is color blind and mediated by one photoreceptor type only. Here, we ask whether this is also the case if the moving stimulus is restricted to a small part of the visual field, and test what influence velocity may have on chromatic motion perception. Honeybees were trained to discriminate between clockwise- and counterclockwise-rotating sector disks. S…

Do transposed-letter similarity effects occur at a prelexical phonological level?

2006

Nonwords created by transposing two letters (e.g., RELOVUTION) are very effective at activating the lexical representation of their base words (Perea & Lupker, 2004). In the present study, we examined whether the nature of transposed-letter (TL) similarity effects was purely orthographic or whether it could also have a phonological component. Specifically, we examined transposed-letter similarity effects for nonwords created by transposing two nonadjacent letters (e.g., relovución– REVOLUCIÓN) in a masked form priming experiment using the lexical decision task (Experiment 1). The controls were (a) a pseudohomophone of the transposed-letter prime ( relobución– REVOLUCIÓN; note that B an…