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Journal of Vision Mar 2021The physical inputs to our visual system are dictated by the interplay between lights and surfaces; thus, for surface color to be stably perceived, the influence of the...
The physical inputs to our visual system are dictated by the interplay between lights and surfaces; thus, for surface color to be stably perceived, the influence of the illuminant must be discounted. To reveal our strategy to infer the illuminant color, we conducted three psychophysical experiments designed to test our optimal color hypothesis that we internalize the physical color gamut under various illuminants and apply the prior to estimate the illuminant color. In each experiment, we presented 61 hexagons arranged without spatial gaps, where the surrounding 60 hexagons were set to have a specific shape in their color distribution. We asked participants to adjust the color of a center test field so that it appeared to be a full-white surface placed under a test illuminant. Results and computational modeling suggested that, although our proposed model is limited in accounting for estimation of illuminant intensity by human observers, it agrees fairly well with the estimates of illuminant chromaticity in most tested conditions. The accuracy of estimation generally outperformed other tested conventional color constancy models. These results support the hypothesis that our visual system can utilize the geometry of scene color distribution to achieve color constancy.
Topics: Color Perception; Computer Simulation; Humans; Lighting; Psychophysics
PubMed: 33661281
DOI: 10.1167/jov.21.3.7 -
Vision Research Jan 1998A prerequisite for higher-level visual tasks such as object recognition is a segmentation of the image into distinct two-dimensional regions. While it has long been...
A prerequisite for higher-level visual tasks such as object recognition is a segmentation of the image into distinct two-dimensional regions. While it has long been assumed that the human visual system jointly exploits region and boundary cues for image segmentation, we report the results of psychophysical experiments which suggest that the visual system relies on geometric properties of bounding contours such as closure and not on the texture of the two-dimensional regions they partition. These findings suggest that the visual system may code and links contours into coherent shapes before surface properties are conjoined.
Topics: Discrimination, Psychological; Form Perception; Humans; Models, Psychological; Photic Stimulation; Psychophysics; Reaction Time
PubMed: 9474385
DOI: 10.1016/s0042-6989(97)00138-7 -
Perception 1996
Topics: Egypt; Germany; History, Medieval; Humans; Optics and Photonics; Psychophysics; Vision, Ocular
PubMed: 9027919
DOI: 10.1068/p251133 -
The Journal of Neuroscience : the... Jul 2003When a target stimulus is embedded in a high contrast surround, the target appears reduced in contrast and is harder to detect, and neural responses in visual cortex are... (Comparative Study)
Comparative Study
When a target stimulus is embedded in a high contrast surround, the target appears reduced in contrast and is harder to detect, and neural responses in visual cortex are suppressed. We used functional magnetic resonance imaging (fMRI) and psychophysics to quantitatively compare these physiological and perceptual effects. Observers performed a contrast discrimination task on a contrast-reversing sinusoidal target grating. The target was either presented in isolation or embedded in a high-contrast surround. While observers performed the task, we also measured fMRI responses as a function of target contrast, both with and without a surround. We found that the surround substantially increased the psychophysical thresholds while reducing fMRI responses. The two data sets were compared, on the basis of the assumption that a fixed response difference is required for correct discrimination, and we found that the psychophysics accounted for 96.5% of the variance in the measured V1 responses. The suppression in visual areas V2 and V3 was stronger, too strong to agree with psychophysics. The good quantitative agreement between psychophysical thresholds and V1 responses suggests V1 as a plausible candidate for mediating surround masking.
Topics: Contrast Sensitivity; Discrimination, Psychological; Female; Fixation, Ocular; Humans; Magnetic Resonance Imaging; Male; Models, Neurological; Neural Inhibition; Perceptual Masking; Photic Stimulation; Psychophysics; Sensory Thresholds; Visual Cortex
PubMed: 12890783
DOI: 10.1523/JNEUROSCI.23-17-06884.2003 -
Vision Research Jan 2019In this study we provide the analysis of eye movement behavior elicited by low-level feature distinctiveness with a dataset of synthetically-generated image patterns....
In this study we provide the analysis of eye movement behavior elicited by low-level feature distinctiveness with a dataset of synthetically-generated image patterns. Design of visual stimuli was inspired by the ones used in previous psychophysical experiments, namely in free-viewing and visual searching tasks, to provide a total of 15 types of stimuli, divided according to the task and feature to be analyzed. Our interest is to analyze the influences of low-level feature contrast between a salient region and the rest of distractors, providing fixation localization characteristics and reaction time of landing inside the salient region. Eye-tracking data was collected from 34 participants during the viewing of a 230 images dataset. Results show that saliency is predominantly and distinctively influenced by: 1. feature type, 2. feature contrast, 3. temporality of fixations, 4. task difficulty and 5. center bias. This experimentation proposes a new psychophysical basis for saliency model evaluation using synthetic images.
Topics: Adult; Attention; Eye Movements; Female; Fixation, Ocular; Humans; Male; Middle Aged; Psychophysics; Visual Perception; Young Adult
PubMed: 30408434
DOI: 10.1016/j.visres.2018.10.006 -
Perception & Psychophysics May 2000Studies of the categorical perception (CP) of sensory continua have a long and rich history in psychophysics. In 1977, Macmillan, Kaplan, and Creelman introduced the use...
Studies of the categorical perception (CP) of sensory continua have a long and rich history in psychophysics. In 1977, Macmillan, Kaplan, and Creelman introduced the use of signal detection theory to CP studies. Anderson and colleagues simultaneously proposed the first neural model for CP, yet this line of research has been less well explored. In this paper, we assess the ability of neural-network models of CP to predict the psychophysical performance of real observers with speech sounds and artificial/novel stimuli. We show that a variety of neural mechanisms are capable of generating the characteristics of CP. Hence, CP may not be a special model of perception but an emergent property of any sufficiently powerful general learning system.
Topics: Humans; Models, Biological; Nerve Net; Perception; Psychophysics; Signal Detection, Psychological
PubMed: 10883589
DOI: 10.3758/bf03206927 -
Proceedings of the National Academy of... Apr 2017Certain numerical abilities appear to be relatively ubiquitous in the animal kingdom, including the ability to recognize and differentiate relative quantities. This...
Certain numerical abilities appear to be relatively ubiquitous in the animal kingdom, including the ability to recognize and differentiate relative quantities. This skill is present in human adults and children, as well as in nonhuman primates and, perhaps surprisingly, is also demonstrated by lower species such as mosquitofish and spiders, despite the absence of cortical computation available to primates. This ubiquity of numerical competence suggests that representations that connect to numerical tasks are likely subserved by evolutionarily conserved regions of the nervous system. Here, we test the hypothesis that the evaluation of relative numerical quantities is subserved by lower-order brain structures in humans. Using a monocular/dichoptic paradigm, across four experiments, we show that the discrimination of displays, consisting of both large (5-80) and small (1-4) numbers of dots, is facilitated in the monocular, subcortical portions of the visual system. This is only the case, however, when observers evaluate larger ratios of 3:1 or 4:1, but not smaller ratios, closer to 1:1. This profile of competence matches closely the skill with which newborn infants and other species can discriminate numerical quantity. These findings suggest conservation of ontogenetically and phylogenetically lower-order systems in adults' numerical abilities. The involvement of subcortical structures in representing numerical quantities provokes a reconsideration of current theories of the neural basis of numerical cognition, inasmuch as it bolsters the cross-species continuity of the biological system for numerical abilities.
Topics: Cerebral Cortex; Female; Humans; Male; Mathematics; Middle Aged; Nontherapeutic Human Experimentation; Photic Stimulation; Psychophysics; Visual Cortex; Visual Perception
PubMed: 28320968
DOI: 10.1073/pnas.1613982114 -
Current Biology : CB Dec 2002Our understanding of how we see color has benefited from the long tradition of visual psychophysics. More recently, models and methods from psychophysics are guiding... (Review)
Review
Our understanding of how we see color has benefited from the long tradition of visual psychophysics. More recently, models and methods from psychophysics are guiding modern neuroimaging experiments on color vision. Combining the two techniques can lead to discoveries that neither can make alone.
Topics: Cerebral Cortex; Color Perception; Humans; Magnetic Resonance Imaging; Psychophysics; Retinal Cone Photoreceptor Cells; Visual Pathways
PubMed: 12498701
DOI: 10.1016/s0960-9822(02)01347-7 -
PLoS Computational Biology Jul 2021In crowding, perception of a target deteriorates in the presence of nearby flankers. Traditionally, it is thought that visual crowding obeys Bouma's law, i.e., all...
In crowding, perception of a target deteriorates in the presence of nearby flankers. Traditionally, it is thought that visual crowding obeys Bouma's law, i.e., all elements within a certain distance interfere with the target, and that adding more elements always leads to stronger crowding. Crowding is predominantly studied using sparse displays (a target surrounded by a few flankers). However, many studies have shown that this approach leads to wrong conclusions about human vision. Van der Burg and colleagues proposed a paradigm to measure crowding in dense displays using genetic algorithms. Displays were selected and combined over several generations to maximize human performance. In contrast to Bouma's law, only the target's nearest neighbours affected performance. Here, we tested various models to explain these results. We used the same genetic algorithm, but instead of selecting displays based on human performance we selected displays based on the model's outputs. We found that all models based on the traditional feedforward pooling framework of vision were unable to reproduce human behaviour. In contrast, all models involving a dedicated grouping stage explained the results successfully. We show how traditional models can be improved by adding a grouping stage.
Topics: Algorithms; Computational Biology; Crowding; Humans; Models, Biological; Neural Networks, Computer; Psychophysics; Vision, Ocular
PubMed: 34228703
DOI: 10.1371/journal.pcbi.1009187 -
Perception 2006
Topics: Discrimination, Psychological; History, 17th Century; Humans; Perception; Psychophysics; Stereognosis; Visual Perception
PubMed: 17286115
DOI: 10.1068/p3511ed