Chapter 18. Attention and Higher Cognition
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|By Jason G. Goldman Most people don't spend much time pondering the diameter of their pupils. The fact is that we don't have much control over our pupils, the openings in the center of the irises that allow light into the eyes. Short of chemical interventions—such as the eyedrops ophthalmologists use to widen their patients' pupils for eye exams—the only way to dilate or shrink the pupils is by changing the amount of available light. Switch off the lamp, and your pupils will widen to take in more light. Step out into the sun, and your pupils will narrow. Mechanical though they may be, the workings of pupils are allowing researchers to explore the parallels between imagination and perception. In a recent series of experiments, University of Oslo cognitive neuroscientists Bruno Laeng and Unni Sulutvedt began by displaying triangles of varying brightness on a computer screen while monitoring the pupils of the study volunteers. The subjects' pupils widened for dark shapes and narrowed for bright ones, as expected. Next, participants were instructed to simply imagine the same triangles. Remarkably, their pupils constricted or dilated as if they had been staring at the actual shapes. Laeng and Sulutvedt saw the same pattern when they asked subjects to imagine more complex scenes, such as a sunny sky or a dark room. Imagination is usually thought of as “a private and subjective experience, which is not accompanied by strongly felt or visible physiological changes,” Laeng says. But the new findings, published in Psychological Science, challenge that idea. The study suggests that imagination and perception may rely on a similar set of neural processes: when you picture a dimly lit restaurant, your brain and body respond, at least to some degree, as if you were in that restaurant. © 2014 Scientific American
by Tom Siegfried Max Planck, who shook the world with his discovery of quantum physics, also offered a warning. “One must be careful,” he said, “when using the word, real.” It was good advice. As physicists explored the quantum domain, they found that usual ideas about reality did not apply. Reality in the realm of atoms was nothing like the world of rocks and baseballs and planets, where Newton’s laws of motions ruled with rigor. Among atoms, the rules were more like Olympic ice skating judging, with unpredictable scores. Gradually physicists, engineers and even screenwriters became familiar with quantum weirdness and used it in lasers, computers and movie plots. Quantum reality might be crazy, but it’s our reality, and most scientists, anyway, have become more or less used to it. Nevertheless, Planck’s warning still applies. Perhaps the quantum picture of reality is another illusion, just like Newton’s was. Human insight into nature may not yet have penetrated reality’s ultimate veil. In other words, maybe reality always dresses itself up in Newtonian or Einsteinian or quantum clothing, and science hasn’t yet seen what reality looks like naked. And that might explain why nature has been able to protect so many of its mysteries from science’s prying eyes — mysteries like the identity of dark matter, the math describing quantum gravity, the mechanism underlying consciousness. And whether humans have free will. Maybe reality always dresses itself up in Newtonian or Einsteinian or quantum clothing, and science hasn’t yet seen what reality looks like naked. © Society for Science & the Public 2000 - 2013.
Link ID: 19319 - Posted: 03.04.2014
By STEPHEN P. HINSHAW and RICHARD M. SCHEFFLER BERKELEY, Calif. — THE writing is on the chalkboard. Over the next few years, America can count on a major expansion of early childhood education. We embrace this trend, but as health policy researchers, we want to raise a major caveat: Unless we’re careful, today’s preschool bandwagon could lead straight to an epidemic of 4- and 5-year-olds wrongfully being told that they have attention deficit hyperactivity disorder. Introducing millions of 3- to 5-year-olds to classrooms and preacademic demands means that many more distracted kids will undoubtedly catch the attention of their teachers. Sure, many children this age are already in preschool, but making the movement universal and embedding transitional-K programs in public schools is bound to increase the pressure. We’re all for high standards, but danger lurks. The American Academy of Pediatrics now endorses the idea that the diagnosis of A.D.H.D. can and should begin at age 4, before problems accumulate. In fact, Adderall and other stimulants are approved for treatment of attentional issues in children as young as 3. Early intervention for children with A.D.H.D. could provide great relief. Children who go untreated have major difficulties in school and with their peers, and they have higher-than-normal rates of accidents and physical injuries. The problem is that millions of American children have been labeled with A.D.H.D. when they don’t truly have it. Our research has revealed a worrisome parallel between our nation’s increasing push for academic achievement and increased school accountability — and skyrocketing A.D.H.D. diagnoses, particularly for the nation’s poorest children. © 2014 The New York Times Company
by Helen Thomson People in a vegetative state showed signs of awareness after electric brain stimulation – and minimally conscious people were able to communicate again TALK about an awakening. People who have been in a minimally conscious state for weeks or years have been temporarily roused using mild electrical stimulation. Soon after it was applied to their brains, 15 people with severe brain damage showed signs of consciousness, including moving their hands or following instructions using their eyes. Two people were even able to answer questions for 2 hours before drifting back into their previous uncommunicative state. "I don't want to give people false hope – these people weren't getting up and walking around – but it shows there is potential for the brain to recover functionality, even several years after damage," says Steven Laureys at the University of Liège in Belgium, who led the research. People with severe brain trauma often fall into a coma. If they "awaken", by showing signs of arousal but not awareness, they are said to be in a vegetative state. This can improve to a state of minimal consciousness, where they might show fluctuating signs of awareness, which come and go, but have no ability to communicate. External stimulation of the brain has been shown to increase arousal, awareness and aspects of cognition in healthy people. So Laureys and his colleagues wondered if it would do the same in people with severe brain damage. They used transcranial direct current stimulation (tDCS), which doesn't directly excite the brain, but uses low-level electrical stimulation to make neurons more or less likely to fire. © Copyright Reed Business Information Ltd.
Link ID: 19301 - Posted: 02.27.2014
by Tom Siegfried If freedom is just another word for nothing left to lose, then “free will” is just another phrase for ability to choose. Bad, wasn’t it? But if free will is an illusion, as many scientists and philosophers have argued, then you shouldn’t blame me. On the other hand, I do blame myself. Because like most bloggers, and possibly even the several dozen humans who don’t blog, I think I decided for myself what to write. Besides, as many investigators of this issue have pointed out, it’s not so obvious that free will is illusory now that quantum mechanics has inserted some randomness into nature. Sadly, though, that reasoning doesn’t get you very far. There’s randomness in the quantum world, all right, just like the unpredictable sequence of winning numbers on a roulette wheel. But in the long run all the numbers turn up about equally often. Free will isn’t worth much if you can’t use it to beat a casino. And as MIT physicist Scott Aaronson points out, quantum math is similar: It gives the odds about what various possible things will happen, and those odds are always predicted precisely. The probability distribution of results is always just what the quantum math says it will be. Aaronson doesn’t see any free will there. Still, the free will question has elicited some sophisticated musing from quantum physicists who like to contemplate the interface of mentality and physical reality. It seems reasonable enough to reexamine such an old question in the light of the latest understanding of the universe. It may be that modern physics can offer a perspective giving hope for those who like to make up their own mind. © Society for Science & the Public 2000 - 2013.
Link ID: 19299 - Posted: 02.27.2014
Sara Reardon Two monkeys sit at computer screens, eyeing one another as they wait for a promised reward: apple juice. Each has a choice — it can either select a symbol that results in juice being shared equally, or pick one that delivers most of the juice to itself. But being selfish is risky. If its partner also chooses not to share, neither gets much juice. This game, the ‘prisoner’s dilemma’, is a classic test of strategy that involves the simultaneous evaluation of an opponent’s thinking. Researchers have now discovered — and manipulated — specific brain circuits in rhesus macaques (Macaca mulatta) that seem to be involved in the animals’ choices, and in their assessments of their partners’ choices. Investigating the connections could shed light on how social context affects decision-making in humans, and how disorders that affect social skills, such as autism spectrum disorder, disrupt brain circuitry. “Once we have identified that there are particular neural signals necessary to drive the processes, we can begin to tinker,” says Michael Platt, a neurobiologist at Duke University in Durham, North Carolina. Neurobiologists Keren Haroush and Ziv Williams of Harvard Medical School in Boston, Massachusetts, zoomed in on neural circuits in rhesus macaques by implanting electrode arrays into a brain area called the dorsal anterior cingulate cortex (dACC), which is associated with rewards and decision-making. The arrays recorded the activity of hundreds of individual neurons. When the monkeys played the prisoner’s dilemma (see ‘A juicy experiment’) against a computer program, they rarely chose to cooperate. But when they played with another monkey that they could see, they were several times more likely to choose to share the juice. © 2014 Nature Publishing Group
|By Lila Stanners Beauty seems mysterious and subjective. Scientists have long attempted to explain why the same object can strike some individuals as breathtaking and others as repulsive. Now a study finds that applying stimulation to a certain brain area enhances people's aesthetic appreciation of visual images. First, participants viewed 70 abstract paintings and sketches and 80 representational (realistic) paintings and photographs and rated how much they liked each one. Then they rated a similar set of images after receiving transcranial direct-current stimulation or sham stimulation. Transcranial direct-current stimulation sends small electrical impulses to the brain through electrodes attached to the head. The technique is noninvasive and cannot be felt, so subjects in the trials were not aware when they received real stimulation. The researchers aimed the impulses at the left dorsolateral prefrontal cortex, an area just behind the brow that is known to be a region critical for emotional processing. They found that the stimulation increased participants' appreciation of representational images, according to the study published online in October 2013 inSocial Cognitive and Affective Neuroscience. The scientists believe the stimulation facilitated a shift from object recognition to aesthetic appraisal for the figurative images; the abstract art was probably being processed by a different area of the brain. This study is one of many recent successful attempts at subtly altering cognition with noninvasive brain stimulation. Some experiments have found that stimulating certain areas allows people to solve math problems or puzzles that formerly had them stumped. Other work suggests these techniques can enhance motor learning, helping athletes or musicians improve at a new sport or a new instrument more rapidly. Experts are quick to point out, however, that these effects are modest enhancements at best—thought induction remains firmly in the realm of science fiction. © 2014 Scientific American
By Michelle Roberts Health editor, BBC News online Doctors have devised a new way to treat amputees with phantom limb pain. Using computer-generated augmented reality, the patient can see and move a virtual arm controlled by their stump. Electric signals from the muscles in the amputated limb "talk" to the computer, allowing real-time movement. Amputee Ture Johanson says his pain has reduced dramatically thanks to the new computer program, which he now uses regularly in his home. He now has periods when he is free of pain and he is no longer woken at night by intense periods of pain. Mr Johanson, who is 73 and lives in Sweden, lost half of his right arm in a car accident 48 years ago. After a below-elbow amputation he faced daily pain and discomfort emanating from his now missing arm and hand. Over the decades he has tried numerous therapies, including hypnosis, to no avail. Within weeks of starting on the augmented reality treatment in Max Ortiz Catalan's clinic at Chalmers University of Technology, his pain has now eased. "The pain is much less now. I still have it often but it is shorter, for only a few seconds where before it was for minutes. BBC © 2014
by Nathan Seppa Women who take acetaminophen during pregnancy are more likely to have a child with attention-deficit/hyperactivity disorder than are women who don’t, according to an analysis of nearly 41,000 pairs of mothers and children in a Danish birth registry. Researchers found that more than half of the women, who gave birth between 1996 and 2002, had used the pain reliever during pregnancy. Calls to the women when the children were 7 years old revealed that children whose moms used any acetaminophen during pregnancy were 37 percent more apt to be diagnosed with ADHD or a related disorder than children whose moms didn’t use the drug. If the women used it in all three trimesters, the apparent risk for offspring was 61 percent higher than for children whose mothers didn’t use the drug. Out of nearly 41,000 children, fewer than 1,000 were diagnosed with ADHD and related disorders. The data establish an association and not cause and effect. But the researchers note that acetaminophen, also sold as Tylenol or Panadol, can cross the placental barrier and may affect hormones in a fetus. Citations Z. Liew et al. Acetaminophen use during pregnancy, behavioral problems, and hyperkinetic disorders. JAMA Pediatrics. Online February 24, 2014. doi:10.1001/jamapediatrics.2013.4914. © Society for Science & the Public 2000 - 2013.
Sara Reardon Freddie Lee Hall loved to gamble, although he usually lost. Winning was better: then he gladly gave the money back to the friends he'd won it from, along with all the wages he earned picking fruit in rural Florida. His friends praised him for this. It made him feel good. And Hall needed to feel good — as court documents make abundantly clear. As a child growing up in the impoverished town of Webster, Florida, he had struggled to keep up with 16 brothers and sisters, who were much smarter than he was. If he failed to understand something, his mother beat him, once while he was tied up in a bag strung over a fire. He stuttered, never learned to read and feared the dark. He was unable to live alone. “Even though he was full grown, mentally he was a child,” his sister Diana told the court. “I had hoped to protect Freddie Lee from the outside world.” But the outside world found him. In 1978, Hall and his friend Mack Ruffin decided to rob a convenience store. They needed a car, so they forced 21-year-old Karol Hurst, who was pregnant, to drive into the woods, where they raped and killed her. Later, one of the pair also shot and killed a sheriff's deputy. When the two men were caught, tried and convicted of murder, the court decided that Hall was the likely ringleader. Ruffin was eventually sentenced to life in prison; Hall was sentenced to death. Next month, after 35 years of failed appeals to have that death sentence commuted to life imprisonment, Hall will have his case heard before the US Supreme Court. His guilt is not in question: the issue is Florida's use of IQ test scores in sentencing him to death. © 2014 Nature Publishing Group,
By ALAN SCHWARZ Jerry, 9 years old, dissolved into his Game Boy while his father described his attentional difficulties to the family pediatrician. The child began flitting around the room distractedly, ignoring the doctor’s questions and squirming in his chair — but then he leapt up and yelled: “Freeze! What do you think is the problem here?” Nine-year-old Jerry was in fact being played by Dr. Peter Jensen, one of the nation’s most prominent child psychiatrists. On this Sunday in January in New York, Dr. Jensen was on a cross-country tour, teaching pediatricians and other medical providers how to properly evaluate children’s mental health issues — especially attention deficit hyperactivity disorder, which some doctors diagnose despite having little professional training. One in seven children in the United States — and almost 20 percent of all boys — receives a diagnosis of A.D.H.D. by the time they turn 18, according to the Centers for Disease Control and Prevention. It narrowly trails asthma as the most common long-term medical condition in children. Increasing concern about the handling of the disorder has raised questions about the training doctors receive before diagnosing the condition and prescribing stimulants like Adderall or Concerta, sometimes with little understanding of the risks. The medications can cause sleep problems, loss of appetite and, in rare cases, delusions. Because the disorder became a widespread national health concern only in the past few decades, many current pediatricians received little formal instruction on it, sometimes only several hours, during their seven years of medical school and residency. But the national scarcity of child psychiatrists has placed much of the burden for evaluating children’s behavioral problems on general pediatricians and family doctors, a reality that Dr. Jensen and others are trying to address through classes that emphasize role-playing exercises and spirited debate. © 2014 The New York Times Company
by Bethany Brookshire CHIGAGO – From a cockatoo bopping to the Backstreet Boys to a sea lion doing the boogie, nothing goes viral like an animal swaying to the music. Now, research shows that not only can bonobos feel the beat, they can play along. Music “engages the brain in a way that no other stimulus can,” says cognitive psychologist Edward Large of the University of Connecticut in Storrs. He and Patricia Gray, a biomusic researcher at the University of North Carolina at Greensboro, wanted to see if bonobos, which share 98.7 percent of their DNA with humans, might respond similarly to musical rhythms. The researchers gave a group of bonobos access to a specially tailored drum, then showed them people drumming rhythmically. Eventually three animals picked up the beat and were able to match tempos with the scientists. Bonobos were also found to prefer a faster pace than most people. Large and Gray presented their findings February 15 at the American Association for the Advancement of Science annual meeting. Rhythm involves the coordination of many brain areas, such as auditory and motor regions. Further research could help scientists understand whether only a few species can keep the beat, or if moving to the groove is widespread in the animal kingdom. © Society for Science & the Public 2000 - 2013.
Kids with ADHD may be able to learn better focus through a computer game that trains the brain to pay attention, a new study suggests. The game was part of a neurofeedback system that used bicycle helmets wired to measure brain waves and gave immediate feedback when kids were paying attention, researchers reported Monday in Pediatrics. Giving kids feedback on what their brains are doing is "like turning on a light switch," said Dr. Naomi Steiner, the study's lead author and a developmental and behavioral pediatrician at the Floating Hospital for Children at Tufts Medical Center. "Kids said 'Oh, this is what people mean when they tell me to pay attention.'" To test the system, Steiner and her colleagues randomly assigned 104 Boston area elementary school children to one of three groups: no treatment, 40 half-hour sessions of neurofeedback or 40 sessions of cognitive therapy. The kids getting neurofeedback wore standard bicycle helmets fitted with brain wave sensors while they performed a variety of exercises on the computer. In one exercise, kids were told to focus on a cartoon dolphin. When people pay attention, theta wave activity goes down while beta waves increase, Steiner explained. If the kids' brains showed they were paying attention, the dolphin would dive to the bottom of the sea. Parents' reports on ADHD symptoms six months later showed a lasting improvement in kids who had done neurofeedback.
Carl Zimmer In 2011, a 66-year-old retired math teacher walked into a London neurological clinic hoping to get some answers. A few years earlier, she explained to the doctors, she had heard someone playing a piano outside her house. But then she realized there was no piano. The phantom piano played longer and longer melodies, like passages from Rachmaninov’s Piano Concerto number 2 in C minor, her doctors recount in a recent study in the journal Cortex. By the time the woman — to whom the doctors refer only by her first name, Sylvia — came to the clinic, the music had become her nearly constant companion. Sylvia hoped the doctors could explain to her what was going on. Sylvia was experiencing a mysterious condition known as musical hallucinations. These are not pop songs that get stuck in your head. A musical hallucination can convince people there is a marching band in the next room, or a full church choir. Nor are musical hallucinations the symptoms of psychosis. People with musical hallucinations usually are psychologically normal — except for the songs they are sure someone is playing. The doctors invited Sylvia to volunteer for a study to better understand the condition. She agreed, and the research turned out to be an important step forward in understanding musical hallucinations. The scientists were able to compare her brain activity when she was experiencing hallucinations that were both quiet and loud — something that had never been done before. By comparing the two states, they found important clues to how the brain generates these illusions. If a broader study supports the initial findings, it could do more than help scientists understand how the brain falls prey to these phantom tunes. It may also shed light on how our minds make sense of the world. © 2014 The New York Times Company
Katherine Sharpe Ben Harkless could not sit still. At home, the athletic ten-year-old preferred doing three activities at once: playing with his iPad, say, while watching television and rolling on an exercise ball. Sometimes he kicked the walls; other times, he literally bounced off them. School was another story, however. Ben sat in class most days with his head down on his desk, “a defeated heap”, remembers his mother, Suzanne Harkless, a social worker in Berkeley, California. His grades were poor, and his teacher was at a loss for what to do. Harkless took Ben to a therapist who diagnosed him with attention deficit hyperactivity disorder (ADHD). He was prescribed methylphenidate, a stimulant used to improve focus in people with the condition. Harkless was reluctant to medicate her child, so she gave him a dose on a morning when she could visit the school to observe. “He didn't whip through his work, but he finished his work,” she says. “And then he went on and helped his classmate next to him. My jaw dropped.” ADHD diagnoses are rising rapidly around the world and especially in the United States, where 11% of children aged between 4 and 17 years old have been diagnosed with the disorder. Between half and two-thirds of those are put on medication, a decision often influenced by a child's difficulties at school. And there are numerous reports of adolescents and young adults without ADHD using the drugs as study aids. © 2014 Nature Publishing Group,
By James Gallagher Health and science reporter, BBC News Brain scans show a complex string of numbers and letters in mathematical formulae can evoke the same sense of beauty as artistic masterpieces and music from the greatest composers. Mathematicians were shown "ugly" and "beautiful" equations while in a brain scanner at University College London. The same emotional brain centres used to appreciate art were being activated by "beautiful" maths. The researchers suggest there may be a neurobiological basis to beauty. The likes of Euler's identity or the Pythagorean identity are rarely mentioned in the same breath as the best of Mozart, Shakespeare and Van Gogh. The study in the journal Frontiers in Human Neuroscience gave 15 mathematicians 60 formula to rate. One of the researchers, Prof Semir Zeki, told the BBC: "A large number of areas of the brain are involved when viewing equations, but when one looks at a formula rated as beautiful it activates the emotional brain - the medial orbito-frontal cortex - like looking at a great painting or listening to a piece of music." The more beautiful they rated the formula, the greater the surge in activity detected during the fMRI (functional magnetic resonance imaging) scans. "Neuroscience can't tell you what beauty is, but if you find it beautiful the medial orbito-frontal cortex is likely to be involved, you can find beauty in anything," he said. To the the untrained eye there may not be much beauty in Euler's identify, but in the study it was the formula of choice for mathematicians. BBC © 2014
By Roy H. Hamilton and Jihad Zreik It's hard to imagine anyone, no matter how brilliant, who doesn't yearn to be even smarter. Thanks to recent advances in neural science, that wish may come true. Researchers are finding ways to rev up the human brain like never before. There would be just one question: Do we really want to inhabit that world? It may be too late to ask. Modern society has already embraced the basic idea of fine-tuning our intellects via artificial procedures—what might be termed “cosmetic” neurology. Schoolchildren take Adderall, Concerta and other attention-focusing medications. Parents and teachers rely on antidepressants and antianxiety drugs. And self-help books offer the latest advances in neuroscience to help ordinary people think faster and sharper. Add to those advances another cognitive-enhancement method: transcranial direct-current stimulation (tDCS). With this technique, electrodes applied to the scalp deliver minuscule amperages of current to the brain. This trickle of electricity seems to cause incremental adjustments in the electrical potentials of membranes in the neurons closest to the electrodes, increasing or decreasing their likelihood of firing. And that, in turn, induces measurable changes in memory, language, mood, motor function, attention and other cognitive domains. Investigators still aren't sure whether tDCS can cause long-term neural changes. Although most tests show only transient effects, there is limited evidence that repeated applications might have more persistent results. The procedure is not approved by the U.S. Food and Drug Administration, and the consensus among experts is that it should be performed only under qualified supervision. Nevertheless, if used properly, it is safe, portable, easy to implement and inexpensive. © 2014 Scientific American
By Molly Sharlach Reader, be proud. You’re a perceptual expert. As you read, your eyes alternately focus and move along each line of text in a seamless sequence honed over years of practice. Reading, recognizing faces and distinguishing colors or musical tones are all forms of perceptual expertise. To appreciate the visual skill involved in reading, turn a text upside down. You’ll stumble along in fits and starts, your eyes pausing longer and more often, each movement bringing less information to your brain. To assess how such neuro-ocular blundering might be improved, researchers at the University of British Columbia asked seven volunteers to practice reading novels upside down. After 30 half-hour sessions over a period of 10 weeks, they gained an average of 35 words per minute in reading speed on inverted text. This could be promising news for people with right hemianopia (hemi-uh-NOH-pee-uh), a condition that erases part of the right field of vision in both eyes. Any damage to the left occipital lobe of the brain, or the pathways connecting it to the eyes, can cause this disorder. Hemianopia, from the Greek for “half sight,” most often results from a stroke, but can also befall patients with multiple sclerosis, brain tumors or traumatic injuries. When we read, we see only three or four letters to the left of our eyes’ fixation point, but we pick up information 10 to 15 letters to the right. So in a society that reads from left to right, left hemianopia has little effect on reading ability, but right hemianopia can be devastating. Brain injury patients rank the inability to read among the most significant effects on their quality of life. © 2014 Scientific America
by Kat Arney Next time you struggle to resist an itchy rash or insect bite, you could find relief in the mirror. Perception of our own bodies can be easily manipulated using tricks such as the rubber hand illusion, which fools people into thinking a rubber hand is their own. Reflecting someone's limb in a mirror has also been used to treat phantom limb pain. Now Christoph Helmchen and his colleagues at the University of Lübeck in Germany have shown that a similar mirror illusion can fool people into feeling relief from an itch, even when they scratch the wrong place. The team injected the right forearms of 26 male volunteers with itch-inducing chemical histamine. Because the injection creates a red spot, they painted a corresponding dot on the opposite arm so both looked identical. One of the researchers then scratched each arm in turn. Unsurprisingly, scratching the itchy arm produced relief, while scratching the other one did not. Next, they placed a large vertical mirror in front of the itchy arm, blocking off the subject's view of their right arm and reflecting back the non-itchy one in its place . They asked the volunteers to look only at the reflected limb in the mirror, whilst a member of the team again scratched each arm. This time the participants felt relief when the unaffected, reflected arm was scratched. © Copyright Reed Business Information Ltd.
Want to read someone’s mind? Look at their pupils. A person about to answer “yes” to a question, especially if they are more used to answering “no,” will have more enlarged pupils than someone about to answer “no,” according to a new study. Normally, pupils dilate when a person is in a darkened environment to let more light into the eye and allow better vision. But pupil size can also be altered by levels of signaling chemicals naturally produced by the brain. In the study, published online this week in the Proceedings of the National Academy of Sciences, scientists observed the pupils of 29 people as they pressed a “yes” or “no” button to indicate whether they’d seen a difficult-to-detect visual cue on a screen in front of them. When a person was deciding how to answer—in the seconds before pressing a button—their pupils grew larger. And if a person was normally biased toward answering “no” when they weren’t sure on the visual cue, then the pupil change was even more profound in the decision-making seconds before a “yes” answer. The finding could lead to new ways to detect people’s intrinsic biases and how confident they are in an answer given, important variables in many sociological and psychological studies. © 2014 American Association for the Advancement of Science.