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Humans rely more on 'inferred' visual objects than 'real' ones -- ScienceDaily

To make sense of the world, humans and animals need to combine information from multiple sources. This is usually done according to how reliable each piece of information is. For example, to know when to cross the street, we usually rely more on what we see than what we hear -- but this can change on a foggy day. "In such situations with the blind spot, the brain 'fills in' the missing information from its surroundings, resulting in no apparent difference in what we see," says senior author Professor Peter König, from the University of Osnabrück's Institute of Cognitive Science. "While this fill-in is normally accurate enough, it is mostly unreliable because no actual information from the real world ever reaches the brain. We wanted to find out if we typically handle this filled-in information differently to real, direct sensory information, or whether we treat it as equal." To do this, König and his team asked study participants to choose between two striped visual images, both of which were displayed to them using shutter glasses. Each image was displayed either partially inside or completely outside the visual blind spot. Both were perceived as identical and 'continuous' due to the filling-in effect, and participants were asked to select the image they thought represented the real, continuous stimulus. "We thought people would either make their choice without preference, or with a preference towards the real stimulus, but exactly the opposite happened -- there was in fact a strong bias towards the filled-in stimulus inside the blind spot," says first author Benedikt Ehinger, researcher at the University of Osnabrück. "Additionally, in an explorative analysis of how long the participants took to make their choice, we saw that they were slightly quicker to choose this stimulus than the one outside the blind spot." So, why are subjects so keen on the blind-spot information when it is essentially the least reliable? The team's interpretation is that subjects compare the internal representation (or 'template') of a continuous stimulus against the incoming sensory input, resulting in an error signal which represents the mismatch. In the absence of real information, no deviation and therefore no error or a smaller signal occurs, ultimately leading to a higher credibility at the decision-making stage. This indicates that perceptual decision-making can rely more on inferred rather than real information, even when there is some knowledge about the reduced reliability of the inferred image available in the brain. "In other words, the implicit knowledge that a filled-in stimulus is less reliable than an external one does not seem to be taken into account for perceptual decision-making," Ehinger explains.

Brain 'rewires' itself to enhance other senses in blind people -- ScienceDaily

"Our results demonstrate that the structural and functional neuroplastic brain changes occurring as a result of early ocular blindness may be more widespread than initially thought," said lead author Corinna M. Bauer, Ph.D., a scientist at Schepens Eye Research Institute of Mass. Eye and Ear and an instructor of ophthalmology at Harvard Medical School. "We observed significant changes not only in the occipital cortex (where vision is processed), but also areas implicated in memory, language processing, and sensory motor functions." The researchers used MRI multimodal brain imaging techniques (specifically, diffusion-based and resting state imaging) to reveal these changes in a group of 12 subjects with early blindness (those born with or who have acquired profound blindness prior to the age of three), and they compared the scans to a group of 16 normally sighted subjects (all subjects were of the same age range). On the scans of those with early blindness, the team observed structural and functional connectivity changes, including evidence of enhanced connections, sending information back and forth between areas of the brain that they did not observe in the normally sighted group. These connections that appear to be unique in those with profound blindness suggest that the brain "rewires" itself in the absence of visual information to boost other senses. This is possible through the process of neuroplasticity, or the ability of our brains to naturally adapt to our experiences.

Blue-eyed humans have a single, common ancestor -- ScienceDaily

"Originally, we all had brown eyes," said Professor Hans Eiberg from the Department of Cellular and Molecular Medicine. "But a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a "switch," which literally "turned off" the ability to produce brown eyes." The OCA2 gene codes for the so-called P protein, which is involved in the production of melanin, the pigment that gives colour to our hair, eyes and skin. The "switch," which is located in the gene adjacent to OCA2 does not, however, turn off the gene entirely, but rather limits its action to reducing the production of melanin in the iris -- effectively "diluting" brown eyes to blue. The switch's effect on OCA2 is very specific therefore. If the OCA2 gene had been completely destroyed or turned off, human beings would be without melanin in their hair, eyes or skin colour -- a condition known as albinism.

Vision, not limbs, led fish onto land 385 million years ago -- ScienceDaily

Neuroscientist and engineer Malcolm A. MacIver of Northwestern and evolutionary biologist and paleontologist Lars Schmitz of Claremont McKenna, Scripps and Pitzer colleges studied the fossil record and discovered that eyes nearly tripled in size before -- not after -- the water-to-land transition. The tripling coincided with a shift in location of the eyes from the side of the head to the top. The expanded visual range of seeing through air may have eventually led to larger brains in early terrestrial vertebrates and the ability to plan and not merely react, as fish do. "Why did we come up onto land 385 million years ago? We are the first to think that vision might have something to do with it," said MacIver, professor of biomedical engineering and of mechanical engineering in the McCormick School of Engineering. "We found a huge increase in visual capability in vertebrates just before the transition from water to land. Our hypothesis is that maybe it was seeing an unexploited cornucopia of food on land -- millipedes, centipedes, spiders and more -- that drove evolution to come up with limbs from fins," MacIver said. (Invertebrates came onto land 50 million years before our vertebrate ancestors made that transition.)

Fractal edges shown to be key to imagery seen in Rorschach inkblots -- ScienceDaily

"As you increase the D value, which makes for more visual complexity, the number of visual perceptions fall off," he said. "People see a lot more patterns in the simple ones." Inkblots with D values of 1.1 generate the highest numbers of perceived images, the team found. The team then put their findings to a human test, generating computerized fractal patterns with varying D values. When seen for 10 seconds by psychology undergraduate psychology students at the University of New South Wales in Australia, the same trend between D values and imagery surfaced. Fractal patterns are also found in the artwork of Jackson Pollock, whose abstract expressionist paintings captured Taylor's lifelong interest in childhood. Pollock's paintings from 1943 to 1952, Taylor has found, are composed of fractals with D values that increased from 1.1 to 1.7. That change was deliberate, Taylor said, as Pollock sought ways to reduce imagery figures seen in his earlier work.

Fractal edges shown to be key to imagery seen in Rorschach inkblots -- ScienceDaily

"These optical illusions seen in inkblots and sometimes in art are important for understanding the human visual system," said Taylor, who is director of the UO Materials Science Institute. "You learn important things from when our eyes get fooled. Fractal patterns in the inkblots are confusing the visual system. Why do you detect a bat or a butterfly when they were never there?"

Why the lights don't dim when we blink: Blinking prompts eye muscles to keep our vision in line -- ScienceDaily

"Our eye muscles are quite sluggish and imprecise, so the brain needs to constantly adapt its motor signals to make sure our eyes are pointing where they're supposed to," Maus said. "Our findings suggest that the brain gauges the difference in what we see before and after a blink, and commands the eye muscles to make the needed corrections." From a big-picture perspective, if we didn't possess this powerful oculomotor mechanism, particularly when blinking, our surroundings would appear shadowy, erratic and jittery, researchers said. "We perceive coherence and not transient blindness because the brain connects the dots for us," said study co-author David Whitney, a psychology professor at UC Berkeley. "Our brains do a lot of prediction to compensate for how we move around in the world," said co-author Patrick Cavanagh, a professor of psychological and brain sciences at Dartmouth College. "It's like a steadicam of the mind." A dozen healthy young adults participated in what Maus jokingly called "the most boring experiment ever." Study participants sat in a dark room for long periods staring at a dot on a screen while infrared cameras tracked their eye movements and eye blinks in real time. Every time they blinked, the dot was moved one centimeter to the right. While participants failed to notice the subtle shift, the brain's oculomotor system registered the movement and learned to reposition the line of vision squarely on the dot. After 30 or so blink-synchronized dot movements, participants' eyes adjusted during each blink and shifted automatically to the spot where they predicted the dot to be. "Even though participants did not consciously register that the dot had moved, their brains did, and adjusted with the corrective eye movement," Maus said. "These findings add to our understanding of how the brain constantly adapts to changes, commanding our muscles to correct for errors in our bodies' own hardware."

For Better Vision, Let the Sunshine In - The New York Times

Strong correlations were found between current eyesight and volunteers’ lifetime exposure to sunlight, above all UVB radiation (which is responsible for burning). Those who had gotten the most sun, particularly between the ages of 14 and 19, were about 25 percent less likely to have developed myopia by middle age. Exposure to sunlight up to the age of 30 also conferred a protective benefit.

Self-generated vision inputs suppressed

That's because the brain can tell if visual motion is self-generated, canceling out information that would otherwise make us feel -- and act -- as if the world was whirling around us. It's an astonishing bit of neural computation -- one that Maimon and his team are attempting to decode in fruit flies. And the results of their most recent investigations, published in Cell on January 5, provide fresh insights into how the brain processes visual information to control behavior. Each time you shift your gaze (and you do so several times a second), the brain sends a command to the eyes to move. But a copy of that command is issued internally to the brain's own visual system, as well. This allows the brain to predict that it is about to receive a flood of visual information resulting from the body's own movement -- and to compensate for it by suppressing or enhancing the activity of particular neurons.

Brain on LSD revealed: First scans show how the drug affects the brain

Under normal conditions, information from our eyes is processed in a part of the brain at the back of the head called the visual cortex. However, when the volunteers took LSD, many additional brain areas -- not just the visual cortex -- contributed to visual processing. Dr Robin Carhart-Harris, from the Department of Medicine at Imperial, who led the research, explained: "We observed brain changes under LSD that suggested our volunteers were 'seeing with their eyes shut' -- albeit they were seeing things from their imagination rather than from the outside world. We saw that many more areas of the brain than normal were contributing to visual processing under LSD -- even though the volunteers' eyes were closed. Furthermore, the size of this effect correlated with volunteers' ratings of complex, dreamlike visions. "

The eyes have it: Mutual gaze potentially a vital component in social interactions: Eye contact may be vital in establishing successful human connections -- ScienceDaily

Indeed, the researchers detected synchronization of eye-blinks, together with enhanced inter-brain synchronization in the IFG, in the pairs when eye contact was established. Compared with findings from previous studies, these outcomes show that synchronization of eye-blinks is not attributable to a common activity, but rather to mutual gaze. This indicates that mutual eye contact might be a crucial component for human face-to-face social interactions, given its potential to bind two individuals into a singular connected system.

Tufte: seeing is thinking

In some ways, seeing is thinking. The light comes in through the lens and is focused on the retina. And the retina is doing - is pretty much working like brain cells. It's processing. And then the two optic nerves are sending what we now know are 20 megabits a second of information back to the brain. That's sure a lot better than my Wi-Fi at home. And so the seeing right then is being transformed into information, into thinking, right as that step from the retina to the brain. And the brain is really busy, and it likes to economize. And so it's quick to be active and jump to conclusions. So if you're told what to look for, you can't see anything else. So one thing is to see, in a way, without words. That avoids the confirmation bias, where, you know, that once you have a point of view, all history will back you up. And that's the eye and brain busy economizing on those 20 megabits a second that are coming in.