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1.
Curr Biol ; 31(5): 936-942.e4, 2021 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-33326771

RESUMO

Anomalous trichromacy is a common form of congenital color deficiency resulting from a genetic alteration in the photopigments of the eye's light receptors. The changes reduce sensitivity to reddish and greenish hues, yet previous work suggests that these observers may experience the world to be more colorful than their altered receptor sensitivities would predict, potentially indicating an amplification of post-receptoral signals. However, past evidence suggesting such a gain adjustment rests on subjective measures of color appearance or salience. We directly tested for neural amplification by using fMRI to measure cortical responses in color-anomalous and normal control observers. Color contrast response functions were measured in two experiments with different tasks to control for attentional factors. Both experiments showed a predictable reduction in chromatic responses for anomalous trichromats in primary visual cortex. However, in later areas V2v and V3v, chromatic responses in the two groups were indistinguishable. Our results provide direct evidence for neural plasticity that compensates for the deficiency in the initial receptor color signals and suggest that the site of this compensation is in early visual cortex.

2.
J Vis ; 20(12): 6, 2020 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-33196769

RESUMO

Previous claims of the number of color categories and corresponding basic color terms in modern Mandarin Chinese remain irreconcilable, mainly due to the shortage in objectively evaluating the basicness of color terms with statistical significance. Therefore the present study applied k-means cluster analysis to investigate native Mandarin Chinese speakers' color naming data of 330 color chips similar to those used in World Color Survey. Results confirmed that there are 11 basic color categories among modern Mandarin speakers in Taiwan, one corresponding to each basic color term. Results also showed that observers overwhelmingly agreed in their use of Mandarin color terms, including those that had yielded ambiguous results in previous studies (gray, brown, pink, and orange). There is significant cross-language similarity when comparing the distribution of color categories in the World Color Survey chart with American English and Japanese data. The motif analysis and group mutual information analysis suggest that Mandarin color terms used in Taiwan describe very similar categories and are, hence, similarly precise in communicating color information as those in Japanese and American English. These results show that three languages of fundamentally different cultures and histories have very similar basic color terms.

3.
Sci Rep ; 10(1): 9273, 2020 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-32518393

RESUMO

To establish a perceptually stable world despite the large retinal shifts caused by saccadic eye movements, the visual system reduces its sensitivity to the displacement of visual stimuli during saccades (e.g. saccadic suppression of displacement, SSD). Previous studies have demonstrated that inserting a temporal blank right after a saccade improves displacement detection performance. This 'blanking effect' suggests that visual information right after the saccade may play an important role in SSD. To understand the mechanisms underlying SSD, we here compare the effect of pre- and post-saccadic stimulus contrast on displacement detection during a saccade with and without inserting a blank. Our results show that observers' sensitivity to detect visual displacement was reduced by increasing post-saccadic stimulus contrast, but a blank relieves the impairment. We successfully explain the results with a model proposing that parvo-pathway signals suppress the magno-pathway processes responsible for detecting displacements across saccades. Our results suggest that the suppression of the magno-pathway by parvo-pathway signals immediately after a saccade causes SSD, which helps to achieve the perceptual stability of the visual world across saccades.

4.
J Opt Soc Am A Opt Image Sci Vis ; 37(4): A154-A162, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32400538

RESUMO

Collinear facilitation (CF) is the improvement of the detection sensitivity of the target when two high-contrast flanking stimuli (flankers) have the same visual properties. While it is known that CF does not occur between achromatic flanking stimuli and chromatic targets, or vice versa, it remains unclear whether CF occurs when the hue of the target and flankers are different. We measured CF for Gabor stimuli defined in an isoluminant plane using stimuli defined by isoluminant colors along isolated cone-opponent axes and in two diagonal directions. The measured CF varied with the difference in hue between the target and flankers. Moreover, increased thresholds were also observed. These results suggest that CF exhibits hue selectivity and involves a suppression as well as a facilitation component. The hue selectivity profile of these factors infer that the CF cannot be simply explained by the assumption of two independent cone opponent mechanisms.

5.
Vision Res ; 172: 11-26, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32388210

RESUMO

Perception of motion in depth is one of the most important visual functions for living in the three-dimensional world. Two binocular cues have been investigated for motion in depth: inter-ocular velocity difference (IOVD) and changing disparity (CD). IOVD provides direction information directly by comparing velocity signals from the two retinas. In this study, we propose for the first time a motion-in-depth model of IOVD that predicts motion-in-depth direction. The model is based on a psychophysical assumption that there are four channels tuned to different directions in depth (Journal of Physiology 235 (1973) 17-29). We modeled these channels by combining outputs of low-level motion detectors that are sensitive to left and right retinal stimulation. Using these channels, we constructed a model of motion in depth that successfully predicted a variety of psychophysical results including direction discrimination, perceived direction, spatial frequency tuning, effect of speed on rotation in depth, effect of lateral motion direction, and effect of binocular and temporal correlations.

6.
J Vis ; 18(13): 6, 2018 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-30535255

RESUMO

Besides specular highlights, image pixels that represent clues to recognizing the object material, such as shading between threads of fabrics, often yield relatively lower luminance in the image. Here, we psychophysically examined how lower and higher luminance components contribute to material perception. We created two types of luminance-modulated images-low- and high-luminance-preserved (LLP and HLP) images-and instructed observers to choose which modified image resulted in a material impression closer to the original. LLP images were created by compressing the luminance contrast of the higher half of the histogram in each original photograph and vice versa. The stimuli were photographs of various samples of stone, wood, leather, and fabric. Although the LLP and HLP images were equally chosen, the choice ratios of the HLP images largely differed across the samples and categories and moderately correlated with the luminance statistics of higher-spatial-frequency sub-bands. These results suggest that either the lower- or higher-luminance components play an important role in material perception, depending on the material category. However, the correlation with sub-band image statistics for stone/wood samples was much weaker than for leather/fabric samples, suggesting that more intricate image characteristics may be involved in evaluating the material impressions of the stone/wood samples.


Assuntos
Percepção de Forma/fisiologia , Luz , Percepção Visual/fisiologia , Percepção de Cores/fisiologia , Sensibilidades de Contraste/fisiologia , Feminino , Humanos , Masculino , Psicofísica
7.
J Vis ; 18(9): 17, 2018 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-30242388

RESUMO

When a rotating object (inducer) is briefly replaced by a static face image (test stimulus), the orientation of the face appears to shift in the rotation direction of the inducer (object orientation induction, OOI). The OOI effect suggests that there is a process to continuously analyze and update the orientation of an object in motion. We investigated the perception of object orientation in motion, examining potential factors that contribute to OOI. Experiment 1 showed that the phenomenon is general to objects rather than specific to faces; OOI could be observed with non-face objects. Experiment 2 showed that OOI is a 3D effect, as the orientation shift for a bent-wire object depended on its configuration in the depth dimension. Experiment 3 showed that salient features are necessary to indicate the intrinsic orientation of the inducing object for producing OOI. Experiment 4 showed that change in the facing direction of the inducer object is a crucial factor for OOI, but neither the object shape nor its identity is important. A strong OOI effect was observed even when the inducer kept changing its shape and identity, as long as its direction change generated continuous rotation. Finally, Experiment 5 showed that OOI is a phenomenon in the pathway for fast visual processing. A single inducer presented shorter than 100ms before influenced the perceived orientation of the test stimulus. Together these results suggest that there is a predictive process that continuously analyzes and updates the orientation of rotating objects, independently of their identification.


Assuntos
Percepção de Movimento/fisiologia , Orientação Espacial/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Rotação , Adulto , Humanos , Masculino , Adulto Jovem
8.
Iperception ; 9(5): 2041669518800507, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30263104

RESUMO

In classic simultaneous color contrast and simultaneous brightness contrast, the color or brightness of a stimulus appears to shift toward the complementary (opposite) color or brightness of its surrounding region. Kaneko and colleagues proposed that simultaneous contrast involves separate "fast" and "slow" mechanisms, with stronger induction effects for fast than slow. Support for the model came from a diverse series of experiments showing that induction by surrounds varying in luminance or color was stronger for brief than long presentation times (10-40 vs. 80-640 ms). Here, to further examine possible underlying processes, we reanalyzed 12 separate small data sets from these studies using correlational and factor analytic techniques. For each analysis, a principal component analysis of induction strength revealed two factors, with one Varimax-rotated factor accounting for brief and one for long durations. In simultaneous brightness experiments, separate factor pairs were obtained for luminance increments and decrements. Despite being based on small sample sizes, the two-factor consistency among 12 analyses would not be expected by chance. The results are consistent with separate fast and slow processes mediating simultaneous contrast for brief and long flashes.

9.
Iperception ; 9(2): 2041669518761731, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29755723

RESUMO

The purpose of the present study is to propose a simple algorithm for color appearance simulation under a color illuminant. Achromatic point is a chromaticity of rays that appear neither red nor green, neither blue nor yellow under a given illuminant condition. Saturation and hue of surface colors are evaluated with respect to the achromatic point of the same lightness, while the achromatic point under a colored illuminant depends on the lightness tested. We previously found that this achromatic point locus can be simply approximated as a line with a parallel offset from the lightness axis of CIE LAB space normalized to daylight. We propose a model that applies shifts in the lightness direction after applying hue/saturation shifts using the cone-response (von Kries) transformation under an iso-lightness constraint, such that achromatic points would be aligned with the lightness axis in the CIE LAB space under daylight normalization. We tested this algorithm, which incorporates evaluation of color appearance in different lightness levels, using #theDress image. Resemblance between our simulation and subjective color-matching results implies that human color vision possibly processes shifts in color and lightness independently, as a previous study reported. Changes in the chromaticity distribution of the images were compared with conventional models, and the proposed model preserved relative color difference better, especially at the lower lightness levels. The better performance in lower lightness levels would be advantageous in displays with wider dynamic range in luminance. This implies that the proposed model is effective in simulating color appearance of images with nonnegligible lightness and color differences.

10.
Sci Rep ; 8(1): 7171, 2018 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-29740127

RESUMO

Spatial representation surrounding a viewer including outside the visual field is crucial for moving around the three-dimensional world. To obtain such spatial representations, we predict that there is a learning process that integrates visual inputs from different viewpoints covering all the 360° visual angles. We report here the learning effect of the spatial layouts on six displays arranged to surround the viewer, showing shortening of visual search time on surrounding layouts that are repeatedly used (contextual cueing effect). The learning effect is found even in the time to reach the display with the target as well as the time to reach the target within the target display, which indicates that there is an implicit learning effect on spatial configurations of stimulus elements across displays. Since, furthermore, the learning effect is found between layouts and the target presented on displays located even 120° apart, this effect should be based on the representation that covers visual information far outside the visual field.


Assuntos
Aprendizagem/fisiologia , Percepção Espacial/fisiologia , Campos Visuais/fisiologia , Percepção Visual/fisiologia , Atenção , Humanos , Orientação/fisiologia , Estimulação Luminosa , Tempo de Reação/fisiologia
12.
J Vis ; 17(4): 7, 2017 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-28423412

RESUMO

Kaneko and Murakami (2012) demonstrated that simultaneous contrast for brightness and color (chromatic saturation) were enhanced by flashing the stimulus very briefly (10 ms). Here we examined whether this effect of duration generalized to other visual features. Tilt illusion and simultaneous hue contrast were both shown to be much stronger with a stimulus duration of 10 ms compared with 500 ms. The similar temporal dynamics for simultaneous contrast across visual features suggest common underlying principles.


Assuntos
Percepção de Cores/fisiologia , Sensibilidades de Contraste/fisiologia , Ilusões/fisiologia , Análise de Variância , Cor , Humanos , Orientação , Estimulação Luminosa/métodos , Fatores de Tempo
13.
J Vis ; 17(3): 1, 2017 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-28249298

RESUMO

Despite numerous prior studies, important questions about the Japanese color lexicon persist, particularly about the number of Japanese basic color terms and their deployment across color space. Here, 57 native Japanese speakers provided monolexemic terms for 320 chromatic and 10 achromatic Munsell color samples. Through k-means cluster analysis we revealed 16 statistically distinct Japanese chromatic categories. These included eight chromatic basic color terms (aka/red, ki/yellow, midori/green, ao/blue, pink, orange, cha/brown, and murasaki/purple) plus eight additional terms: mizu ("water")/light blue, hada ("skin tone")/peach, kon ("indigo")/dark blue, matcha ("green tea")/yellow-green, enji/maroon, oudo ("sand or mud")/mustard, yamabuki ("globeflower")/gold, and cream. Of these additional terms, mizu was used by 98% of informants, and emerged as a strong candidate for a 12th Japanese basic color term. Japanese and American English color-naming systems were broadly similar, except for color categories in one language (mizu, kon, teal, lavender, magenta, lime) that had no equivalent in the other. Our analysis revealed two statistically distinct Japanese motifs (or color-naming systems), which differed mainly in the extension of mizu across our color palette. Comparison of the present data with an earlier study by Uchikawa & Boynton (1987) suggests that some changes in the Japanese color lexicon have occurred over the last 30 years.


Assuntos
Biometria/métodos , Percepção de Cores/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Análise por Conglomerados , Cor , Feminino , Humanos , Japão , Masculino
14.
Sci Rep ; 6: 35513, 2016 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-27759056

RESUMO

Visual attention spreads over a range around the focus as the spotlight metaphor describes. Spatial spread of attentional enhancement and local selection/inhibition are crucial factors determining the profile of the spatial attention. Enhancement and ignorance/suppression are opposite effects of attention, and appeared to be mutually exclusive. Yet, no unified view of the factors has been provided despite their necessity for understanding the functions of spatial attention. This report provides electroencephalographic and behavioral evidence for the attentional spread at an early stage and selection/inhibition at a later stage of visual processing. Steady state visual evoked potential showed broad spatial tuning whereas the P3 component of the event related potential showed local selection or inhibition of the adjacent areas. Based on these results, we propose a two-stage model of spatial attention with broad spread at an early stage and local selection at a later stage.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Atenção/fisiologia , Comportamento/fisiologia , Ciências Biocomportamentais , Potenciais Evocados Visuais , Percepção Espacial/fisiologia , Percepção Visual/fisiologia , Adulto , Eletroencefalografia , Humanos , Masculino , Estimulação Luminosa , Campos Visuais , Adulto Jovem
15.
J Opt Soc Am A Opt Image Sci Vis ; 33(3): A150-63, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26974919

RESUMO

We compared the color-discrimination thresholds and supra-threshold color differences (STCDs) obtained in complete chromatic adaptation (gray) and incomplete chromatic adaptation (red). The color-difference profiles were examined by evaluating the perceptual distances between various color pairs using maximum likelihood difference scaling. In the gray condition, the chromaticities corresponding with the smallest threshold and the largest color difference were almost identical. In contrast, in the red condition, they were dissociated. The peaks of the sensitivity functions derived from the color-discrimination thresholds and STCDs along the L-M axis were systematically different between the adaptation conditions. These results suggest that the color signals involved in color discrimination and STCD tasks are controlled by separate mechanisms with different characteristic properties.


Assuntos
Adaptação Ocular/fisiologia , Percepção de Cores/fisiologia , Discriminação Psicológica/fisiologia , Sensibilidades de Contraste/fisiologia , Humanos , Modelos Biológicos , Estimulação Luminosa
16.
Proc Natl Acad Sci U S A ; 113(9): 2370-5, 2016 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-26858441

RESUMO

Perceptual color space is continuous; however, we tend to divide it into only a small number of categories. It is unclear whether categorical color perception is obtained solely through the development of the visual system or whether it is affected by language acquisition. To address this issue, we recruited prelinguistic infants (5- to 7-mo-olds) to measure changes in brain activity in relation to categorical color differences by using near-infrared spectroscopy (NIRS). We presented two sets of geometric figures to infants: One set altered in color between green and blue, and the other set altered between two different shades of green. We found a significant increase in hemodynamic responses during the between-category alternations, but not during the within-category alternations. These differences in hemodynamic response based on categorical relationship were observed only in the bilateral occipitotemporal regions, and not in the occipital region. We confirmed that categorical color differences yield behavioral differences in infants. We also observed comparable hemodynamic responses to categorical color differences in adults. The present study provided the first evidence, to our knowledge, that colors of different categories are represented differently in the visual cortex of prelinguistic infants, which implies that color categories may develop independently before language acquisition.


Assuntos
Percepção de Cores , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Humanos , Lactente , Comportamento do Lactente
17.
Vision Res ; 117: 59-66, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26475088

RESUMO

Despite decades of attempts to create a model for predicting gaze locations by using saliency maps, a highly accurate gaze prediction model for general conditions has yet to be devised. In this study, we propose a gaze prediction method based on head direction that can improve the accuracy of any model. We used a probability distribution of eye position based on head direction (static eye-head coordination) and added this information to a model of saliency-based visual attention. Using empirical data on eye and head directions while observers were viewing natural scenes, we estimated a probability distribution of eye position. We then combined the relationship between eye position and head direction with visual saliency to predict gaze locations. The model showed that information on head direction improved the prediction accuracy. Further, there was no difference in the gaze prediction accuracy between the two models using information on head direction with and without eye-head coordination. Therefore, information on head direction is useful for predicting gaze location when it is available. Furthermore, this gaze prediction model can be applied relatively easily to many daily situations such as during walking.


Assuntos
Atenção , Olho/anatomia & histologia , Fixação Ocular/fisiologia , Cabeça/anatomia & histologia , Desempenho Psicomotor , Percepção Visual/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
18.
Cereb Cortex ; 25(12): 4869-84, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26423093

RESUMO

The variability of color-selective neurons in human visual cortex is considered more diverse than cone-opponent mechanisms. We addressed this issue by deriving histograms of hue-selective voxels measured using fMRI with a novel stimulation paradigm, where the stimulus hue changed continuously. Despite the large between-subject difference in hue-selective histograms, individual voxels exhibited selectivity for intermediate hues, such as purple, cyan, and orange, in addition to those along cone-opponent axes. In order to rule the possibility out that the selectivity for intermediate hues emerged through spatial summation of activities of neurons selectively responding to cone-opponent signals, we further tested hue-selective adaptations in intermediate directions of cone-opponent axes, by measuring responses to 4 diagonal hues during concurrent adaptation to 1 of the 4 hues. The selective and unidirectional reduction in response to the adapted hue lends supports to our argument that cortical neurons respond selectively to intermediate hues.


Assuntos
Percepção de Cores/fisiologia , Córtex Visual/fisiologia , Adaptação Fisiológica , Mapeamento Encefálico , Cor , Sensibilidades de Contraste , Humanos , Imagem por Ressonância Magnética , Estimulação Luminosa , Psicofísica
19.
J Vis ; 15(8): 4, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26057547

RESUMO

The mode of color appearance (mode) is a concept suggesting that variations in a medium that emits, transmits, or reflects light can cause differences in color appearance. For example, the same light beams that appear brown (or gray) when reflected from a given object surface may appear orange (or white) when emitted from a light source. The present study investigated the relationships between material perception and perceived mode, especially in terms of luminosity. In the experiment, a rotating spheroid was presented with surrounds of various luminance levels. The surface texture of the spheroid was either matte gray (three surface reflectance levels) or one of two fabrics. The participants were asked to evaluate the luminosity (mode) and perceived reflectance of the object. The results show that the mode perception is clearly different from the lightness perception. The luminosity was fit with a linear function of the lightness scale in CIE (Commission Internationale de l'Éclairage) L* value of the object surface, unless the material of the surface was identifiable. To conclude, the luminosity (mode) perception can be strongly affected by the material percept, and the luminosity perception of the same object can vary when its surface property is ambiguous.


Assuntos
Percepção de Cores/fisiologia , Percepção de Forma/fisiologia , Luz , Reconhecimento Visual de Modelos/fisiologia , Adulto , Feminino , Humanos , Masculino , Limiar Sensorial , Propriedades de Superfície
20.
PLoS One ; 10(3): e0121035, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25799510

RESUMO

We investigated coordinated movements between the eyes and head ("eye-head coordination") in relation to vision for action. Several studies have measured eye and head movements during a single gaze shift, focusing on the mechanisms of motor control during eye-head coordination. However, in everyday life, gaze shifts occur sequentially and are accompanied by movements of the head and body. Under such conditions, visual cognitive processing influences eye movements and might also influence eye-head coordination because sequential gaze shifts include cycles of visual processing (fixation) and data acquisition (gaze shifts). In the present study, we examined how the eyes and head move in coordination during visual search in a large visual field. Subjects moved their eyes, head, and body without restriction inside a 360° visual display system. We found patterns of eye-head coordination that differed those observed in single gaze-shift studies. First, we frequently observed multiple saccades during one continuous head movement, and the contribution of head movement to gaze shifts increased as the number of saccades increased. This relationship between head movements and sequential gaze shifts suggests eye-head coordination over several saccade-fixation sequences; this could be related to cognitive processing because saccade-fixation cycles are the result of visual cognitive processing. Second, distribution bias of eye position during gaze fixation was highly correlated with head orientation. The distribution peak of eye position was biased in the same direction as head orientation. This influence of head orientation suggests that eye-head coordination is involved in gaze fixation, when the visual system processes retinal information. This further supports the role of eye-head coordination in visual cognitive processing.


Assuntos
Desempenho Psicomotor/fisiologia , Visão Ocular/fisiologia , Adulto , Movimentos Oculares , Feminino , Movimentos da Cabeça , Humanos , Masculino , Adulto Jovem
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