http://precedings.nature.com/tags/Vision Recently posted documents tagged with 'Vision' Nature Publishing Group en Nature Precedings http://precedings.nature.com/images/header_logo.gif http://precedings.nature.com http://precedings.nature.com/documents/3789/version/1 Visual filling-in relates to a perceptual phenomenon in which a stimulus pattern apparently undergoes dynamic changes assuming an attribute such as colour, texture, or brightness from the surround. This perceptual completion effect has up to now been shown only for real images. Here, we present filling-in in negative afterimages, a phenomenon not yet reported. Using coloured disk-ring patterns for stimuli, we demonstrate that afterimage filling-in arises independently, and is not simply a replica of filling-in observed in real images. Such filling-in does not occur when the afterimage is elicited dichoptically, suggesting its emergence within the monocular visual pathway. In this way, our findings indicate that filling-in under certain conditions may derive from an active neural mechanism located at low levels of the visual pathway. http://precedings.nature.com/documents/3789/version/1 Mon, 21 Sep 2009 13:00:28 UTC An illusion induced by an illusion -perceptual filling-in of coloured negative afterimages hdl:10101/npre.2009.3789.1 2009-09-21 Adam Geremek Nature Precedings 2009-09-21T13:00:28Z Manuscript Neuroscience http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/3436/version/1 The interconnection between vision and somatosensation is already well-established and is further supplemented by the evolutionary link between eyes and photoreceptors, and the functional connection between photosensation and thermoreception. However, our analysis hypothesizes a possibility that vision is not just linked to somatosensation, but may not exist without somatosensation. Surprisingly, our photoreceptor itself needs somatosensory proteins for its functioning, and our entire visual pathway depends on somatosensory cues for its functioning. http://precedings.nature.com/documents/3436/version/1 Fri, 17 Jul 2009 14:46:25 UTC Can Vision Exist Without Somatosensation? hdl:10101/npre.2009.3436.1 2009-07-17 Manivannan Muniyandi Nature Precedings 2009-07-17T14:46:25Z Manuscript Molecular Cell Biology Neuroscience http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/3373/version/1 Ours, is the first application of dynamical evolutionary games to decision making in neuroscience. Firing neurons are the players. The strategy is their firing rate. Neurons with equal firing rates define a population. The neurons do not know the rules of the game, they do not know what the reward is, they are not required to be rational and they do not even know they are playing the game. Interactions are inhibitory. The theory confirms experimental data about decision making in vision: (i ) A parameter of the game model determines how many populations of neurons participate in the decision; (ii ) the solution of the game dictates how many loci in the brain participate in the decision; (iii ) the theory clarifies the difference between ultimate and proximate factors and predicts that quick decisions are associated with more errors and slow decision are associated with fewer errors. http://precedings.nature.com/documents/3373/version/1 Mon, 29 Jun 2009 11:32:12 UTC Evolutionary game theory and the evolution of neuron populations, ring rates, and decisionmaking hdl:10101/npre.2009.3373.1 2009-07-10 Yosef Cohen Nature Precedings 2009-06-29T11:32:12Z Manuscript Neuroscience http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/3023/version/1 Rewarding improves performance. Is it due to modulations of the output modules of the neural systems or are there mechanisms favoring more ‘generous’ inputs? Some recent study included V1 in the the circuitry of reward-based modulations, but the effects of reward can easily be confused with effects of attention. Here we address this issue with a psychophysical dual task to control attention while orientation sensitivity on targets associated to different levels of reward is measured. We found that different reward rates improve orientation discrimination and sharpen the internal response distributions. Data are unaffected by changing attentional load nor by dissociating the feature of the reward cue from the feature relevant for the task. This suggests that reward may act independently on attention by modulating the activity of early sensory stages, perhaps V1, through a SNR improvement of task-relevant channels. Reward acts like attention, but using separate channels. http://precedings.nature.com/documents/3023/version/1 Fri, 03 Apr 2009 11:28:56 UTC Reward sharpens orientation coding independently on attention hdl:10101/npre.2009.3023.1 2009-04-03 Stefano Baldassi Nature Precedings 2009-04-03T11:28:56Z Manuscript Neuroscience http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/2792/version/1 We have recently suggested that numerosity is a primary sensory attribute, showing that it is strongly susceptible to adaptation. Here we use the Method of Single Stimuli (MSS) to show that observers can extract a running average of the numerosity of a succession of stimuli and hold it in mind for use as a standard of comparison for subsequent stimuli. Accuracy and precision of judgments are high and not reduced by potentially misleading variables like texture density or display area. http://precedings.nature.com/documents/2792/version/1 Fri, 16 Jan 2009 16:29:46 UTC Vision senses number directly hdl:10101/npre.2009.2792.1 2009-01-16 David C. Burr Nature Precedings 2009-01-16T16:29:46Z Manuscript Neuroscience http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/2675/version/1 Robust and versatile perception of the world is augmented considerably when information from our five separate sensory systems is combined. Much recent evidence has demonstrated near-optimal integration across senses, but it remains unclear at what level the integration occurs, at a "sensory" or "decisional" level. Here we show that non-informative "pedestal" motion stimuli in one sensory modality (vision or touch) selectively lowers thresholds in the other, to the same degree as pedestals in the same modality: strong evidence for functionally important cross-sensory integration at early levels of sensory processing. http://precedings.nature.com/documents/2675/version/1 Thu, 18 Dec 2008 13:45:36 UTC Cross-modal facilitation of visual and tactile motion hdl:10101/npre.2008.2675.1 2008-12-18 David Burr Nature Precedings 2008-12-18T13:45:36Z Manuscript Neuroscience http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/1729/version/1 Dyslexic individuals have deficits in detecting visual stimuli embedded in high levels of perceptual noise. Here we show that visually symptomatic dyslexics, who otherwise had elevated contrast thresholds for discriminating symbols in visual noise, had thresholds similar to non-dyslexics when wearing colored filters. These findings provide evidence that colored filters, which minimize the visual distortions and discomfort of dyslexics when reading, improve dyslexics’ noise exclusion to normal levels. http://precedings.nature.com/documents/1729/version/1 Thu, 27 Mar 2008 15:03:25 UTC Colored filters improve exclusion of perceptual noise in visually symptomatic dyslexics hdl:10101/npre.2008.1729.1 2008-03-27 Velitchko Manahilov Nature Precedings 2008-03-27T15:03:25Z Manuscript Neuroscience http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/1686/version/1 Exploring representations is a fundamental step towards understanding vision. The visual system carries two types of information along separate pathways: One is about what it is and the other is about where it is. Initially, the what is represented by a pattern of activity that is distributed across millions of photoreceptors, whereas the where is ‘implicitly’ given as their retinotopic positions. Many computational theories of object recognition rely on such pixel-based representations, but they are insufficient to learn spatial information such as position and size due to the implicit encoding of the where information. Here we try transforming a retinal image of an object into its internal image via interchanging the what with the where, which means that patterns of intensity in internal image describe the spatial information rather than the object information. To be concrete, the retinal image of an object is deformed and turned over into a negative image, in which light areas appear dark and vice versa, and the object’s spatial information is quantified with levels of intensity on borders of that image. Interestingly, the inner part excluding the borders of the internal image shows the position and scale invariance. In order to further understand how the internal image associates the what and where, we examined the internal image of a face which moves or is scaled on the retina. As a result, we found that the internal images form a linear vector space under the object translation and scaling. In conclusion, these results show that the what-where interchangeability might play an important role for organizing those two into internal representation of brain. http://precedings.nature.com/documents/1686/version/1 Fri, 14 Mar 2008 13:32:50 UTC Representing an Object by Interchanging What with Where hdl:10101/npre.2008.1686.1 2008-03-14 Jong-Hoon Ahn Nature Precedings 2008-03-14T13:32:50Z Manuscript Neuroscience http://creativecommons.org/licenses/by/3.0/ http://dx.doi.org/10.1038/npre.2008.1584.1 A number of investigators have found perceptual deficits in schizophrenic subjects. It has also been indicated that those with schizophrenia suffer from reduced attention. This raises the possibility that their perceptual deficits may wholly or in part reflect attentional effects. The present study used computer simulations to examine the potential effects of inattention on performance measures determined with three psychophysical methods: the Two Alternative Forced Choice (2-AFC) Staircase Method, the Two Alternative Forced Choice (2-AFC) Fixed Stimuli Method, and the Yes/No Method. It is shown that both 2-AFC methods are susceptible to attentional effects but, in contrast, the Yes/No Method may allow for the differentiation of attentional effects from sensory sensitivity and subjective criterion effects. The simulations indicate that it may be possible to control for attention effects by using Yes/No Method in combination to a 2AFC method. http://dx.doi.org/10.1038/npre.2008.1584.1 Mon, 11 Feb 2008 22:30:36 UTC Perceptual deficits and inattention in schizophrenia doi:10.1038/npre.2008.1584.1 2008-02-11 John R. Skoyles Nature Precedings 2008-02-11T22:30:36Z Manuscript Neuroscience http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/1521/version/1 Several studies have shown that adults integrate visual and haptic information (and information from other modalities) in a statistically optimal fashion, weighting each sense according to its reliability. To date no studies have investigated when this capacity for cross-modal integration develops. Here we show that prior to eight years of age, integration of visual and haptic spatial information is far from optimal, with either vision or touch dominating totally, even in conditions where the dominant sense is far less precise than the other (assessed by discrimination thresholds). For size discrimination, haptic information dominates in determining both perceived size and discrimination thresholds, while for orientation discrimination vision dominates. By eight-ten years, the integration becomes statistically optimal, like adults. We suggest that during development, perceptual systems require constant recalibration, for which cross-sensory comparison is important. Using one sense to calibrate the other precludes useful combination of the two sources. http://precedings.nature.com/documents/1521/version/1 Wed, 16 Jan 2008 16:00:34 UTC Young children do not integrate visual and haptic information hdl:10101/npre.2008.1521.1 2008-01-16 David C. Burr Nature Precedings 2008-01-16T16:00:34Z Manuscript Neuroscience http://creativecommons.org/licenses/by/3.0/