Chapter 10. Vision: From Eye to Brain
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Sandrine Ceurstemont, editor, New Scientist TV It's the closest any of us are likely to get to telekinesis. New animations created by Stuart Anstis from the University of California, San Diego, are showing how changing your gaze can alter the direction in which objects are moving. If you watch this video normally, the moving circles in the first animation rotate while the shifting dots in the second clip follow a horizontal path. But if you look away and watch the movie out of the corner of your eye, the direction of motion will appear to change. In both cases, the moving objects seem to follow the direction of the background stripes. The illusion proves that we perceive motion very differently when it's in the periphery compared with when it's picked up by the fovea, a tiny area at the back of the eye responsible for central vision. Looking at a scene directly results in the sharpest vision, whereas our peripheral vision is good at picking up motion but poor at making out the details of shapes. "That's why when you wave at someone in a crowded airport, your peripheral motion detectors pick up the motion and an eye movement steers the target onto the fovea for more detailed analysis," says Anstis. The animation was a finalist in the 2012 Best Illusion of the Year Contest and was presented earlier this month at the event gala in Naples, Florida. © Copyright Reed Business Information Ltd
Link ID: 16842 - Posted: 05.26.2012
Sandrine Ceurstemont, editor, New Scientist TV Think this animated man is running to the left? Switch your point of view and you may change your mind. Created by Steven Thurman and Hongjing Lu from the University of California, Los Angeles, the animation is most commonly seen as a man running to the left when viewed directly. But by fixing your eyes on the red cross so that it appears in your peripheral vision, the man seems to move to the right. According to the researchers, they manipulated the animation to induce the switch by adjusting features of the discs making up the man's body. Their orientation and drifting speed represent what our brain would expect from a person walking to the right. The illusion was one of the finalists in this year's Best Illusion of the Year Contest. © Copyright Reed Business Information Ltd.
Link ID: 16815 - Posted: 05.19.2012
Sandrine Ceurstemont, editor, New Scientist TV Brad Pitt may look attractive when seen head on. But an illusion that presents photos viewed in your peripheral vision shows how pretty faces can quickly look ugly. The effect was discovered accidentally by psychology student Sean Murphy from the University of Queensland in Australia while looking at photos for another experiment. He went on to study the illusion with colleagues who discovered that the distortion occurs when the eyes of a series of photos are aligned and presented quickly in succession. The transformation is caused by differences between faces that follow each other, for example big eyes will seem to bulge if preceded by squinting eyes. The illusion was published last year but now the team has created this new video that shows the effect more dramatically. The illusion has won second prize in this year's Best Illusion of the Year contest. © Copyright Reed Business Information Ltd.
Link ID: 16806 - Posted: 05.17.2012
Caroline Morley, online picture researcher On the edge of your vision as you read this, the water swirls but the starfish turns in the other direction, floating above the background. The image itself is, of course, still: the movement is created in your head. It uses the phenomenon of periphery drift to make us see movement where there is none. The different contrasts between the colours are the key to making us see the star and the background move in opposite directions. This image was created by Kaia Nao, an alternative identity for wildlife painter Joe Hautman. It is a finalist in the 2012 Best Illusion of the Year Contest, run by the Neural Correlate Society to encourage and publicise the work of researchers in the field of visual illusions. See the winning video in our New Scientist TV post "Best illusion of 2012: The disappearing hand trick". © Copyright Reed Business Information Ltd.
Link ID: 16797 - Posted: 05.16.2012
By Rachel Ehrenberg Specialized goggles that send information to solar cell–like chips implanted in the eyes may one day help some blind people seeThe new implants, which have been tested in rat retinas in a dish, would require less invasive surgery than similar devices now being tested and offer a higher-resolution view of the world. The new system, reported online May 13 in Nature Photonics, still needs work before being tested in people. But one day it may return partial sight to people suffering from conditions such as retinitis pigmentosa, an inherited disease that can lead to night blindness and tunnel vision, or macular degeneration, in which sharp central vision is lost but peripheral vision remains. In those conditions, vision suffers when light-detecting cells at the back of the inner eye are damaged, even though the nerve cells that send visual information to the brain may remain intact. No current treatments can restore vision for such retinal damage, says Lotfi Merabet, an eye specialist at Massachusetts Eye and Ear in Boston. The new work “is certainly very promising,” he says. Developing the implants took many years and many scientists, says study coauthor James Loudin, an electrical engineer at Stanford University. “The sheer number of new technologies that had to be developed — it’s amazing,” he says. © Society for Science & the Public 2000 - 2012
Sandrine Ceurstemont, editor, New Scientist TV Think you can tell which way a ballerina is twirling? A new animation by psychophysiologist Marcel de Heer shows that a dancer's silhouette is identical regardless of the direction in which she is spinning. The video starts with two mirror-image ballerinas spinning in opposite ways and a third one in silhouette, which could belong to either dancer. So how does our brain make sense of the ambiguous figure? The perceived direction of motion varies from person to person. According to de Heer, our visual system makes a quick decision on a subconscious level about the direction of rotation and the result of that decision is what we see. "It makes this choice while there is a big chance it is the wrong one," he says. An online study of a similar illusion revealed that most people see the silhouette moving clockwise. However those who initially see it turning counterclockwise are more likely to be able to reverse its direction of motion. In the course of the animation, all three ballerinas become silhouettes, at which point their motion is perceived to be synchronised. The reason for this is unclear but de Heer plans to investigate the phenomenon in future research. © Copyright Reed Business Information Ltd.
Link ID: 16783 - Posted: 05.12.2012
Sandrine Ceurstemont, editor, New Scientist TV Seeing an object move doesn't actually mean that it's moving. In this video, the psychedelic patterns might look like they're rotating, but pause the video and you'll see that they are actually static images. This striking illusion, created by visual perception researcher Akiyoshi Kitaoka from Ritsumeikan University in Japan, is commonly known as the 'rotating snakes' and exploits a peripheral vision effect where motion is perceived in one direction due to gradual changes in brightness of segments in the pattern. Rounded edges also seem to enhance the illusion. The brain trick was thought to occur when our eyes slowly move across the image. But now a new study by Susana Martinez-Conde from Barrow Neurological Institute in Phoenix, Arizona, and colleagues is uncovering that superfast eye movements are responsible for the phantom motion. Since the effect isn't perceived continuously, the team tracked eye movements of volunteers just before they started to see rotation. They found that people usually blinked, or moved their eyes so quickly they didn't realise it, right before their brain was tricked. Conversely, their eyes were stable when they didn't perceive motion. © Copyright Reed Business Information Ltd.
Link ID: 16750 - Posted: 05.05.2012
By LISA SANDERS, M.D. On Thursday I challenged Well readers to figure out a medical mystery involving a middle-aged woman who learned she had an unusual disease after visiting an ophthalmologist. The case was surprising because the woman didn’t feel sick, yet the doctor made the diagnosis just by looking at her and asking her a few simple questions that confirmed his diagnostic suspicions. The first reader to figure it out completely was Dr. Eric Gierke, a neurologist at Swedish Medical Center in Seattle. He said he recognized the condition because he had a patient who had acromegaly and only a few very subtle physical changes. In submitting his answer, Dr. Gierke also guessed one of the questions that the diagnosing physician asked the patient — “Has your shoe size changed recently?” — making him the clear winner. A few other readers also guessed both the questions and the diagnosis, but Dr. Gierke was first and the most specific. In all, 16 readers figured out the correct diagnosis. Well done! Acromegaly is a disease caused by a tumor, usually found in the pituitary gland, that secretes an excess of growth hormone, the blood chemical that tells our bodies to grow. Children with acromegaly can grow to extraordinary stature. André the Giant, the French professional wrestler and actor whose height was billed at 7 feet 4 inches, and Richard Kiel, the 7-foot-2 actor who played the villain Jaws in two James Bond movies, both had acromegaly from childhood. Their distinctive faces reveal some of the characteristic acromegalic changes: Their brows are prominent, and they have wide, square chins and large noses. Copyright 2012 The New York Times Company
By Matt McGrath Science reporter, BBC World Service Up to 90% of school leavers in major Asian cities are suffering from myopia - short-sightedness - a study suggests. Researchers say the "extraordinary rise" in the problem is being caused by students working very hard in school and missing out on outdoor light. The scientists told the Lancet that up to one in five of these students could experience severe visual impairment and even blindness. In the UK, the average level of myopia is between 20% and 30%. According to Professor Ian Morgan, who led this study and is from the Australian National University, 20-30% was once the average among people in South East Asia as well. "What we've done is written a review of all the evidence which suggests that something extraordinary has happened in east Asia in the last two generations," he told BBC News. "They've gone from something like 20% myopia in the population to well over 80%, heading for 90% in young adults, and as they get adult it will just spread through the population. It certainly poses a major health problem." BBC © 2012
Tom Lawrence The first UK clinical trials of an electronic eye implant designed to restore the sight of blind people have proved successful and "exceeded expectations", scientists said today. Eye experts developing the pioneering new technology said the first group of British patients to receive the electronic microchips were regaining "useful vision" just weeks after undergoing surgery. The news will offer fresh hope for people suffering from retinitis pigmentosa (RP) - a genetic eye condition that leads to incurable blindness. Retina Implant AG, a leading developer of subretinal implants, fitted two RP sufferers with the wireless device in mid-April as part of its UK trial. The patients were able to detect light immediately after the microchip was activated, while further testing revealed there were also able to locate white objects on a dark background, Retina Implant said. Ten more British sufferers will be fitted with the devices as part of the British trial, which is being led by Tim Jackson, a consultant retinal surgeon at King's College Hospital and Robert MacLaren, a professor of Ophthalmology at the University of Oxford and a consultant retinal surgeon at the Oxford Eye Hospital. © independent.co.uk
At two years, Avastin (bevacizumab) and Lucentis (ranibizumab injection), two widely used drugs to treat age-related macular degeneration (AMD), improve vision when administered monthly or on an as needed basis, although greater improvements in vision were seen with monthly administration for this common, debilitating eye disease, according to researchers supported by the National Institutes of Health. Of the two drugs, Avastin is most frequently used to treat AMD.However, prior to the Comparison of AMD Treatments Trials (CATT), a two-year clinical trial, the two drugs had never been compared head-to-head. Second year results were published today in the journal Ophthalmology. First year results were published in the May 19, 2011 issue of the New England Journal of Medicine. AMD is the leading cause of vision loss and blindness in older Americans. In its advanced stages, the wet form of AMD spurs the growth of abnormal blood vessels, which leak fluid and blood into the macula and obscure vision. The macula is the central portion of the retina that allows us to look straight ahead and to perceive fine visual detail. Accumulation of fluid and blood damages the macula, causing loss of central vision, which can severely impede mobility and independence. Without treatment, most patients become unable to drive, read, recognize faces or perform tasks that require hand-eye coordination. Avastin and Lucentis block growth of abnormal blood vessels and leakage of fluid from the vessels.
Sandrine Ceurstemont, editor, New Scientist TV Think your eyes can detect if an object is upright? A new illusion by video producer Greg Ross shows that it's not always the case as visual detail can sometimes fool our brain. In this video, a balance beam is filled in with a diagonal pattern. Does it seem to be skewed? Keep watching as the lines are slowly removed. Do you notice a difference when the drawing is white? The balance beam should look tilted when it's covered with lines but upright when they are erased. However, measuring the distance between the blocks would prove that the top and bottom are parallel in both cases. According to Ross, the effect is due to the opposing direction of diagonal lines in each rectangle. But the triangle placed on the right side of the top beam accentuates the effect. "We perceive it as weighing down on the right side but only when the diagonal lines are there," says Ross. A similar effect can be observed in other optical illusions, for example radiating lines covering a shape can make it appear to bend. Highlighting the corners of squares on a chessboard can also distort the alignment. © Copyright Reed Business Information Ltd.
Link ID: 16721 - Posted: 04.28.2012
By Laura Sanders Tiny eye movements and blinking can make perfectly frozen snakes appear to dance, a new study shows. The results help explain the mystery of how the Rotating Snakes illusion tricks the brain. Earlier studies have suggested that the perception of motion is triggered by the eyes drifting slowly away from a central target when viewing the illusion. But by tracking eye movements in eight volunteers, vision neuroscientists at the Barrow Neurological Institute in Phoenix found a different explanation. Participants held down a button when the snakes seemed to swirl and lifted the button when the snakes appeared still. Right before the snakes started to move, participants began blinking more and making short jumpy eye movements called microsaccades, Jorge Otero-Millan, Stephen Macknik and Susana Martinez-Conde report in the April 25 Journal of Neuroscience. When volunteers’ rates of microsaccades slowed down, the visual illusion faded and the snakes were more likely to stop moving. The results join a growing number of studies that use magic tricks and illusions to reveal people’s perceptual mistakes, such as seeing motion where there is none. Studying the mismatch between perception and reality may lead to a deeper understanding of the mind. © Society for Science & the Public 2000 - 2012
Link ID: 16713 - Posted: 04.26.2012
By Sandra G. Boodman, Liisa Ecola lay on the sofa in the living room of her Capitol Hill home counting the hours until she could see a specialist who, she fervently hoped, would tell her why she could no longer keep her eyes open. For several months, the 42-year-old transportation policy researcher for Rand had been squinting, even in the dark. Her puzzled optometrist had suggested she consult a neuro-ophthalmologist, a doctor who specializes in diseases of the eye originating in the central nervous system. Ecola had waited weeks to get an appointment, which was scheduled for Dec. 15, 2010. But the day before, Ecola recalled, “I opened my laptop and my eyes snapped shut.” To her horror, she discovered that her eyes would stay open only for a few minutes at a time. Panicked, she called the specialist to confirm the appointment, only to discover that she wouldn’t be seeing him at all. The office had no record of her. “I was really scared,” said Ecola, who called it the lowest moment in her quest for a diagnosis. “I was convinced I had a brain tumor.” Her problem turned out to be far less serious and far more easily treated. The following day she lucked into an appointment with another specialist, who explained the odd constellation of symptoms that had left her unable to leave her house. For several years, Ecola had suffered an unexplained, intermittent facial tic, in which she scrunched up her face as if she were tasting something awful. Because it seemed linked to stress, Ecola consulted a behavioral therapist in an effort to banish it through habit reversal training — using relaxation exercises and making a conscious effort to stop the tic. Until early 2010, the treatment usually worked, and Ecola seemed able to control it. © 1996-2012 The Washington Post
Leila Haghighat At the turn of the twentieth century, the promise of regenerating damaged tissue was so far-fetched that Thomas Hunt Morgan, despairing that his work on earthworms could ever be applied to humans, abandoned the field to study heredity instead. Though he won the Nobel Prize in 1933 for his work on the role of chromosomes in inheritance, if he lived today, the advances in regenerative medicine may have tempted him to reconsider. Three studies published this week show that introducing new cells into mice can replace diseased cells — whether hair, eye or heart — and help to restore the normal function of those cells. These proof-of-principle studies now have researchers setting their sights on clinical trials to see if the procedures could work in humans. “You can grow cells in a Petri dish, but that’s not regenerative medicine,” says Robin Ali, a geneticist at University College London, who led the eye study. “You have to think about the biology of repair in a living system.” Sprouting hair In work published in Nature Communications, Japanese researchers grew different types of hair on nude mice, using stem cells from normal mice and balding humans to recreate the follicles from which hair normally emerges1. Takashi Tsuji, a regenerative-medicine specialist at Tokyo University of Science who led the study, says that the technique holds promise for treating male pattern baldness. © 2012 Nature Publishing Group
By Tina Hesman Saey The farmer’s wife in the nursery rhyme Three Blind Mice may need a different mouse hunting strategy. Thanks to new cell transplants, some formerly night-blind mice can see in the dark again, perhaps even well enough to evade the carving knife of the farmer’s wife. Injections of light-gathering nerve cells called rods into the retinas of night-blind mice integrated into the brain’s visual system and restored sight, Robin Ali of the University College London Institute of Ophthalmology and colleagues report online April 18 in Nature. The finding gives new hope that cell transplants may reverse damage to the brain and eyes caused by degenerative diseases and help heal spinal cord injuries. Other researchers have tried, and failed, to repair damaged retinas with stem cell transplants, says Christian Schmeer, a neurologist at the University Hospital Jena in Germany. The new study is the first to demonstrate that transplanted nerve cells can restore function. "They show it is possible and they do it convincingly," Schmeer says. At the same time, Schmeer cautions, “there’s still a lot to be done until it’s ready for clinical use.” In the study, Ali’s group transplanted immature rod cells from newborn mice into the retinas of adult mice. Rods, found in the back of the eye, work in dim light conditions. Other retina cells called cones sense bright light. In previous studies, the researchers had been able to transplant about 1,000 rods into mice’s retinas, but that wasn’t enough to restore vision. By optimizing techniques, the researchers coaxed about 26,000 rod cells to incorporate into the retina of each injected eye. © Society for Science & the Public 2000 - 2012
By Julian De Freitas and Brandon Liverence Notice that, even as you fixate on the screen in front of you, you can still shift your attention to different regions in your peripheries. For decades, cognitive scientists have conceptualized attention as akin to a shifting spotlight that “illuminates” regions it shines upon, or as a zoom lens, focusing on things so that we see them in finer detail. These metaphors are commonplace because they capture the intuition that attention illuminates or sharpens things, and thus, enhances our perception of them. Some of the important early studies to directly confirm this intuition were conducted by NYU psychologist Marisa Carrasco and colleagues, who showed that attention enhances the perceived sharpness of attended patterns. In their experiment, participants saw two textured patterns presented side-by-side on a computer screen, and judged which of the two patterns looked sharper. However, just before the patterns appeared, an attention-attracting cue was flashed at the upcoming location of one of the patterns. They found that attended patterns were perceived as sharper than physically identical unattended patterns. In other words, attention may make physically blurry (or otherwise degraded) images appear sharper – much like a zoom lens on a camera. Subsequent studies by Carrasco’s group and others found that attention also enhances perception of other features – for example, color saturation , orientation , and speed . This research suggests that attention causes incoming sensory information from attended locations to be processed more fully, without changing the information itself. © 2012 Scientific American,
By Charles Q. Choi and LiveScience The order in which colors are named worldwide appears to be due to how eyes work, suggest computer simulations with virtual people. These findings suggest that wavelengths of color that are easier to see also get names earlier in the evolution of a culture. A common question in philosophy is whether or not we all see the world the same way. One strategy that scientists have for investigating that question is to see what colors get names in different cultures. Intriguingly, past research has found that colors familiar to one culture might not have names in another, suggesting different cultures indeed have distinct ways of understanding the world. One mystery scientists have uncovered is that color names always seem to appear in a specific order of importance across cultures—black, white, red, green, yellow and blue. "For example, if a population has a name for red, it also has a name for black and for white; or, if it has a name for green, it also has a name for red," said researcher Francesca Tria, a physicist at the ISI Foundation in Turin, Italy. But if a population has a name for black and white, that doesn't necessarily mean they have a name for red. To solve the puzzle of this color-name hierarchy, Tria and her colleagues devised a computer simulation with pairs of virtual people, or "agents," who lacked the knowledge of names for colors. One agent, the speaker, is shown two or more objects, invents a name for a color to describe one of the objects, and refers to the item by that color. The other agent, the hearer, then has to guess which item, and thus color, the speaker referred to. Scientists repeated this until all the agents came to a consensus on color names. © 2012 Scientific American
by Andy Coghlan THE blind hunter sees. It may not have eyes, but the hydra - a centimetre-long relative of the jellyfish - still senses light to detect and kill its prey. This finding is part of efforts to uncover the evolutionary origins of sight. Two years ago, David Plachetzki of the University of California at Davis showed that Hydra magnipapillata has genes that are involved in light detection. These include the gene coding for opsin, a protein that is key to all animal vision. To find out how the hydra uses these genes, Plachetzki and his colleagues looked at which cells expressed them. This pointed to a complex of cells that is connected to the hydra's hunting equipment. The hydra kills its prey with stings that are propelled like harpoonsMovie Camera. When Plachetzki's team exposed tanks of hydra to periods of bright and dim light, the hydra ejected twice as many stings under dim conditions. This, the team says, shows that hydra use light levels to hunt (BMC Biology, DOI: 10.1186/1741-7007-10-17). H. magnipapillata may have been one of the first creatures to develop sensitivity to light. Possible explanations for this sensitivity could be that the hydra hunts at dusk when food is more plentiful or by sensing changes in light intensity - releasing stings when the shadows of prey pass overhead. © Copyright Reed Business Information Ltd.
Sandrine Ceurstemont, editor, New Scientist TV An illusion that tricks your brain twice is helping to uncover how we perceive ghostly images. The new animation, created by Irene Sperandio from the University of Western Ontario in London, Canada, and colleagues, combines an after-image effect with a common size illusion to investigate how these colourful apparitions are generated. While watching the video above, fix your eyes on the dot in the centre. A bluish contour should start to emerge around the red circle, which is the beginning of the after-image. At the same time, the second effect alters your perception of the static circle's size. Since the main circle is surrounded by a group of smaller ones, it appears to be larger than it actually is. Once the animation stops, a ghostly blue circle should appear when you look at the grey background. But instead of being the same size as the original circle, it should appear to be slightly larger due to adaptation induced by viewing it in the context of the surrounding discs. "The size of the after-image should correspond to the perceived size of the static inner circle which is affected by the flickering stimuli," says Sperandio. Since the flashing circles don't produce an after-image, this suggests that the effect is residual. © Copyright Reed Business Information Ltd.
Link ID: 16648 - Posted: 04.14.2012