How We Decide

Until now, most psychology and neural imaging research have focused on how humans learn behavior through trial and error. 

However, Carnegie Mellon University neuroscientists Matthew M. Walsh and John R. Anderson have found that this view is incomplete. 

In their study published in the Proceedings of the National Academy of Sciences (PNAS), Walsh and Anderson show how the brain uses both instruction and experience to select actions. 

This identification of separate neural systems that control behavior also suggests that damage to one may not impair the other. 

"With most decisions that we make, we have access to both experience and instruction sources of information, so it is overly simplistic to just consider one," said Walsh, a doctoral student in the Department of Psychology within CMU's Dietrich College of Humanities and Social Sciences. 

"By tapping different neural learning systems, we can facilitate learning in patient populations. For example, Parkinson's disease is associated with a loss of dopamine and an impaired ability to learn from experience. Consequently, Parkinson's patients may more readily learn from instruction than experience." 

For the study, Walsh and Anderson used electroencephalography (EEG) to measure participants' neural activity during experiments designed to explore how instruction influences trial and error learning.   

The participants were shown two symbols that were assigned different reward values. Their goal was to maximize their reward by selecting the symbol that was more likely to be rewarded within each pair. 

One group received a description of the rewards before choosing, while the other group only received feedback about whether their choices were rewarded. 

The results showed that participants who did not receive instruction gradually learned from experience. Participants who did receive instruction performed perfectly from the beginning. 

Walsh and Anderson focused their analyses on the feedback-related negativity (FRN), a neural signal of reward learning. 

In striking contrast to their behavior, the FRN only developed once participants experienced outcomes in both conditions of the experiment. Thus, while instruction governed behavior, experience controlled the FRN. 

"Little research to this point has looked at how instruction engages behavior," said Walsh. 

"Our work shows that different systems in the brain control behavior, and that one system may learn from experience while the other controls responses." 

Anderson, the R.K. Mellon University Professor of Psychology and Computer Science, has spent the past three decades combining cognitive psychology research with computer science to understand how the brain works, how people learn and how computer-based instructional systems can be used as educational aids. 

For his trailblazing contributions, he received the 2011 Benjamin Franklin Medal in Computer and Cognitive Science. 

"These results highlight a striking dissociation between behavioral and neural responses. While instruction may immediately control behavior, certain neural responses must be learned from experience. Although some theories anticipate such a dissociation, this is the most direct evidence to date," said Anderson. 

Source: Carnegie Mellon University [December 12, 2011]

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Learning Matrix Style: Vision Scientists Demonstrate Innovative Learning Method

New research published December 8 in the journal Science suggests it may be possible to use brain technology to learn to play a piano, reduce mental stress or hit a curve ball with little or no conscious effort. It's the kind of thing seen in Hollywood's "Matrix" franchise. 

In the future, a person may be able to watch a computer screen and have his or her brain patterns modified to improve physical or mental performance. Researchers say an innovative learning method that uses decoded functional magnetic resonance imaging could modify brain activities to help people recuperate from an accident or disease, learn a new language or even fly a plane [Credit: Nicolle Rager Fuller, National Science Foundation]

Experiments conducted at Boston University (BU) and ATR Computational Neuroscience Laboratories in Kyoto, Japan, recently demonstrated that through a person's visual cortex, researchers could use decoded functional magnetic resonance imaging (fMRI) to induce brain activity patterns to match a previously known target state and thereby improve performance on visual tasks. 

Think of a person watching a computer screen and having his or her brain patterns modified to match those of a high-performing athlete or modified to recuperate from an accident or disease. Though preliminary, researchers say such possibilities may exist in the future. 

"Adult early visual areas are sufficiently plastic to cause visual perceptual learning," said lead author and BU neuroscientist Takeo Watanabe of the part of the brain analyzed in the study. 

Neuroscientists have found that pictures gradually build up inside a person's brain, appearing first as lines, edges, shapes, colors and motion in early visual areas. The brain then fills in greater detail to make a red ball appear as a red ball, for example. 

Researchers studied the early visual areas for their ability to cause improvements in visual performance and learning. 

"Some previous research confirmed a correlation between improving visual performance and changes in early visual areas, while other researchers found correlations in higher visual and decision areas," said Watanabe, director of BU's Visual Science Laboratory. "However, none of these studies directly addressed the question of whether early visual areas are sufficiently plastic to cause visual perceptual learning." Until now. 

Boston University post-doctoral fellow Kazuhisa Shibata designed and implemented a method using decoded fMRI neurofeedback to induce a particular activation pattern in targeted early visual areas that corresponded to a pattern evoked by a specific visual feature in a brain region of interest. The researchers then tested whether repetitions of the activation pattern caused visual performance improvement on that visual feature. 

The result, say researchers, is a novel learning approach sufficient to cause long-lasting improvement in tasks that require visual performance. 

What's more, the approached worked even when test subjects were not aware of what they were learning. 

"The most surprising thing in this study is that mere inductions of neural activation patterns corresponding to a specific visual feature led to visual performance improvement on the visual feature, without presenting the feature or subjects' awareness of what was to be learned," said Watanabe, who developed the idea for the research project along with Mitsuo Kawato, director of ATR lab and Yuka Sasaki, an assistant in neuroscience at Massachusetts General Hospital. 

"We found that subjects were not aware of what was to be learned while behavioral data obtained before and after the neurofeedback training showed that subjects' visual performance improved specifically for the target orientation, which was used in the neurofeedback training," he said. 

The finding brings up an inevitable question. Is hypnosis or a type of automated learning a potential outcome of the research? 

"In theory, hypnosis or a type of automated learning is a potential outcome," said Kawato. "However, in this study we confirmed the validity of our method only in visual perceptual learning. So we have to test if the method works in other types of learning in the future. At the same time, we have to be careful so that this method is not used in an unethical way." 

At present, the decoded neurofeedback method might be used for various types of learning, including memory, motor and rehabilitation. 

The National Science Foundation, the National Institutes of Health and the Ministry of Education, Culture, Sports, Science and Technology in Japan supported the research. 

Source: National Science Foundation [December 08, 2011]

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Where is the accurate memory? The eyes have it

The witness points out the criminal in a police lineup. She swears she’d remember that face forever. Then DNA evidence shows she’s got the wrong guy. It happens so frequently that many courts are looking with extreme skepticism at eyewitness testimony. 

Is there a way to get a more accurate reading of memory? A new study says yes. “Eye movements are drawn quickly to remembered objects,” says Deborah Hannula, assistant professor at the University of Wisconsin Milwaukee, who conducted the study with Carol L. Baym and Neal J. Cohen of the University of Illinois, Urbana-Champaign and David E. Warren of the University of Iowa College of Medicine. Tracking where and for how long a person focuses his or her eyes “can distinguish previously seen from novel materials even when behavioral reports fail to do so.” The findings will appear in an upcoming issue of Psychological Science, a journal published by the Association for Psychological Science. 

The researchers gave university students 36 faces to study. These target faces were also morphed to produce images closely resembling them; the morphed phases were not seen during the study phase. The students were then shown 36 three-face displays, one at a time. Told that the studied faces wouldn’t always be there, the participants had to press a button indicating which face was the studied one, or simply choose a face if they felt none had been studied. They then reported verbally whether the studied target face was present or not. While they looked at the 3-face display, their eye movements were recorded, tracking where the eyes focused first and what proportion of time was spent looking there. For the analysis, the psychologists divided the faces into three groups: studied targets; morphs mistaken for the “target” face; and morphs chosen and known to be incorrect. 

Participants easily identified the target faces most of the time. They also spent more time looking at these faces, and did so soon after the 3-face display had been presented. “The really interesting finding is that before they chose a face and pressed a button, there was disproportionate viewing of the target faces as compared to either type of selected face,” said Hannula. However, “after the response was made, viewing tended to mimic the behavioral endorsement of a face as studied or not, whether that endorsement was correct or incorrect.” In other words, “pre-response viewing seems to reflect actual experience, and post-response viewing seems to reflect the decision making process and whether or not the face will be endorsed as studied.” 

Hannula theorizes as to what is happening: “Early disproportionate viewing of the target face may precede and help give rise to awareness that a particular face has been studied. Subsequently, we begin to think about the choice that we’re making”—we look closely, compare and weigh the options—“these cognitive processes permit us to make a decision, but may also lead us down the wrong path. In this case, leading us to endorse a face as studied despite having never seen it before.” 

Aside from the potential for practical application, says Hannula, eye movement methods could be used to examine memory in individuals—like some psychiatric patients and children – who may have trouble communicating what it is that they remember. “Eye movements might provide us with more information about what exactly these individuals remember than behavioral reports alone.” 

Source: Association for Psychological Science [December 02, 2011]

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Even unconsciously, sound helps us see

“Imagine you are playing ping-pong with a friend. Your friend makes a serve. Information about where and when the ball hit the table is provided by both vision and hearing. Scientists have believed that each of the senses produces an estimate relevant for the task (in this example, about the location or time of the ball’s impact) and then these votes get combined subconsciously according to rules that take into account which sense is more reliable. And this is how the senses interact in how we perceive the world. However, our findings show that the senses of hearing and vision can also interact at a more basic level, before they each even produce an estimate,” says Ladan Shams, a UCLA professor of psychology, and the senior author of a new study appearing in the December issue of Psychological Science, a journal published by the Association for Psychological Science. 

[Credit: Oscar Burriel/Science Photo Library]

“If we think of the perceptual system as a democracy where each sense is like a person casting a vote and all votes are counted (albeit with different weights) to reach a decision, what our study shows is that the voters talk to one another and influence one another even before each casts a vote.” 

“The senses affect each other in many ways,” says cognitive neuroscientist Robyn Kim. There are connections between the auditory and visual portions of the brain and at the cognitive level. When the information from one sense is ambiguous, another sense can step in and clarify or ratify the perception. Now, for the first time, Kim, Megan Peters, and Ladan Shams, working at the University of California Los Angeles, have shown behavioral evidence that this interplay happens in the earliest workings of perception—not just before that logical decision-making stage, but before the pre-conscious combination of sensory information. 

To demonstrate that one sense can affect another even before perception, the researchers showed 63 participants a bunch of dots on a screen, in two phases with a pause between them. In one phase, the dots moved around at random; in the other, some proportion moved together from right to left. The participants had to indicate in which phase the dots moved together horizontally. In experiment 1, the subjects were divided into three groups. While they looked at the dots, one group heard sound moving in the same direction as the right-to-left dots, and stationary sound in the random phase. A second group heard the same right-to-left sound in both phases. The third group heard the identical sound in both phases, but it moved in the opposite direction of the dots. In the second and third conditions, because the sound was exactly the same in both phases, it added no cognitively useful information about which phase had the leftward-moving dots. In experiment 2, each participant experienced trials in all three conditions. 

The results: All did best under the first condition—when the sound moved only in the leftward-motion phase. The opposite-moving sound neither enhanced nor worsened the visual perception. But surprisingly, the uninformative sound—the one that traveled leftward both with the leftward-moving dots and also when the dots moved randomly—helped people correctly perceive when the dots were moving from one side to the other. Hearing enhanced seeing, even though the added sense couldn’t help them make the choice. 

The study, says Kim, should add to our appreciation of the complexity of our senses. “Most of us understand that smell affects taste. But people tend to think that what they see is what they see and what they hear is what they hear.” The findings of this study offer “further evidence that, even at a non-conscious level, visual and auditory processes are not so straightforward,” she says. “Perception is actually a very complex thing affected by many factors.” 

“This study shows that at least in regards to perception of moving objects, hearing and sight are deeply intertwined, to the degree that even when sound is completely irrelevant to the task, it still influences the way we see the world,” Shams says. 

Source: Association for Psychological Science [December 01, 2011]

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Why do some people never forget a face?

"Face recognition is an important social skill, but not all of us are equally good at it," says Beijing Normal University cognitive psychologist Jia Liu. But what accounts for the difference? 

A new study by Liu and colleagues Ruosi Wang, Jingguang Li, Huizhen Fang, and Moqian Tian provides the first experimental evidence that the inequality of abilities is rooted in the unique way in which the mind perceives faces. 

"Individuals who process faces more holistically"—that is, as an integrated whole—"are better at face recognition," says Liu. The findings will appear in an upcoming issue of Psychological Science, a journal published by the Association for Psychological Science. 

In daily life, we recognize faces both holistically and also "analytically"—that is, picking out individual parts, such as eyes or nose. But while the brain uses analytical processing for all kinds of objects—cars, houses, animals—"holistic processing is thought to be especially critical to face recognition," says Liu. 

To isolate holistic processing as the key to face recognition, the researchers first measured the ability of study participants—337 male and female students—to remember whole faces, using a task in which they had to select studied faces and flowers from among unfamiliar ones. 

The next two tasks measured performance in tasks that mark holistic processing. The composite-face effect (CFE) shows up when two faces are split horizontally and stuck together. It's easier to identify the top half-face when it's misaligned with the bottom one than when the two halves are fitted smoothly together. 

"That's because our brain automatically combines them to form a new"—and unfamiliar—"face," says Liu: evidence of holistic processing. 

The other marker of holistic processing is the whole-part effect (WPE). In this one, people are shown a face, then asked to recognize a part of it—say, the nose. They do better when the feature is presented within the whole face than when it stands on its own among other noses: again, we remember the nose integrated into the whole face. The researchers also assessed participants' general intelligence. 

The results: Those participants who scored higher on CFE and WPE—that is, who did well in holistic processing—also performed better at the first task of recognizing faces. But there was no link between facial recognition and general intelligence, which is made up of various cognitive processes—a suggestion that face processing is unique. 

"Our findings partly explains why some never forget faces, while others misrecognize their friends and relatives frequently," says Liu. 

That's why the research holds promise for therapies for that second category of people, who may suffer disorders such as prosopagnosia (face blindness) and autism. 

Knowing that the mind receives a face as one whole thing and not as a collection of individual parts, "we may train people on holistic processing to improve their ability in recognizing faces," Liu says. 

Source: Association for Psychological Science [December 02, 2011]

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Roles of conscious and sub-conscious awareness distinguished by new research

What distinguishes information processing with conscious awareness from processing occurring without awareness? And, is there any role for conscious awareness in information processing, or is it just a byproduct, like the steam from the chimney of a train engine, which is significant, but has no functional role? 

These questions - which have long puzzled psychologists, philosophers, and neurobiologists - were recently addressed in a study by Hebrew University of Jerusalem researchers and published by the journal Psychological Science. 

The study was headed by Prof. Leon Deouell from the Hebrew University’s Edmond and Lily Safra Center for Brain Sciences (ELSC) and Department of Psychology and Prof. Dominique Lamy from the Department of Psychology at Tel Aviv University, and conducted by research student Liad Mudirk of Tel Aviv University with collaboration of research student Assaf Breska from the Hebrew University. 

We are not consciously aware of most of the input that hits upon our sensory systems.  Yet subjectively, conscious awareness dominates our mental activity. “One of the dominant theories in cognitive sciences and psychology posits that parts of the information perceived without awareness may be processed to a certain extent,” says Prof. Deouell. “Yet to bind the different parts of a complex input into something meaningful and coherent requires conscious awareness. 

To test this theory, the research team ran a study in which they presented participants with pictures of natural scenes including some human action, like a picture of basketball players jumping to reach a ball. 

In other tests, the same scenes were presented -- except that the central object was replaced by another, unlikely object. For example, the basketball was replaced by a watermelon. 

The participants viewed the pictures through a mirror stereoscope, a simple device that allowed the research team to present the pictures to only one eye. At the same time, the other eye viewed rapidly flickering patterns of colors which drew the subjects' attention, so that the participants were not aware for many seconds that anything was presented to their other eye. This allowed the researchers to measure how long it takes normal and unusual scenes to “win the competition” against the flickering pattern and break into awareness. 

"We found that participants became aware of the unusual scenes earlier than to the usual scenes," commented Deouell. "The conclusion was that even before the participants were aware of the existence of the picture, the semantic relationships between parts of the scene were interpreted." 

The study shows that, counter to previous theories, integration is not the prerogative of conscious awareness but is achieved even without awareness. When and why then do we need conscious awareness? 

The findings of this research suggest that when the results of the integration between parts of the input are incompatible with expectations or prior knowledge, awareness is required in order to account for the conundrum. Thus, the study expands the realm of unaware processes, yet shows that conscious awareness is not a meaningful luxury - it allows us to deal with novel and unexpected situations. 

Source: Hebrew University of Jerusalem via AlphaGalileo [November 30, 2011]

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Colour is not a black and white issue

Scientists at the University of Hull have found that some people have the ability to hallucinate colours at will -- even without the help of hypnosis. 

Brain activity [Credit: University of Hull]

The study, published this week in the journal Consciousness and Cognition, was carried out in the Department of Psychology at the University of Hull. It focused on a group of people that had shown themselves to be 'highly suggestible' in hypnosis. 

The subjects were asked to look at a series of monochrome patterns and to see colour in them. They were tested under hypnosis and without hypnosis and both times reported that they were able to see colours. 

Individuals' reactions to the patterns were also captured using an MRI scanner, which enabled the researchers to monitor differences in brain activity between the suggestible and non-suggestible subjects. The results of the research, showed significant changes in brain activity in areas of the brain responsible for visual perception among the suggestible subjects only. 

Professor Giuliana Mazzoni, lead researcher on the project says: "These are very talented people. They can change their perception and experience of the world in ways that the rest of us cannot." 

The ability to change experience at will can be very useful. Research has shown that hypnotic suggestions can be used to block pain and increase the effectiveness of psychotherapy. 

It has always been assumed that hypnosis was needed for these effects to occur, but the new study suggests that this is not true. Although hypnosis does seem to heighten the subjects' ability to see colour, the suggestible subjects were also able to see colours and change their brain activity even without the help of hypnosis. 

The MRI scans also showed clearly that although it was not necessary for the subjects to be under hypnosis to be able to perceive colours in the tests, it was evident that hypnosis increased the ability of the subjects to experience these effects. 

Dr William McGeown, who also contributed to the study, says: "Many people are afraid of hypnosis, although it appears to be very effective in helping with certain medical interventions, particularly pain control. The work we have been doing shows that certain people may benefit from suggestion without the need for hypnosis." 

The study, which was partially funded by the BBC, used a control group formed of less suggestible people, or people less likely to respond to hypnosis. It was found that this group of people were not able to hallucinate colour and, again, these reported results were supported by MRI scans. 

Source: University of Hull [November 30, 2011]

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When errors improve performance: Model describes how experiences influence our perception

During estimation processes we unconsciously make use of recent experiences. Scientists from Ludwig-Maximilians-Universität (LMU) in Munich and the Bernstein Center Munich asked test subjects to estimate distances in a virtual reality environment. The results revealed that estimates tended to approach the mean of all previously experienced distances. For the first time, scientists were able to accurately predict the experimental findings using a mathematical model. The model combines two well-known laws of psychophysics with a theorem from probability theory. The study could be of fundamental relevance to research on perception. 

Why do we perceive identical distances as long in one situation and short in another? It all depends on the distances that we have covered in the immediate past. This might seem a trivial conclusion, but it gives an important insight into how the brain processes signals of different intensities or even abstract elements such as numbers. Dr. Stefan Glasauer (LMU Munich), project leader at the Bernstein Center Munich, and PhD student Frederike Petzschner have investigated this effect both experimentally and theoretically. Test subjects were first asked to perform certain displacements in virtual reality and then to reproduce these displacements as accurately as possible. As in previous studies, the results showed a bias towards the mean of all previously experienced displacements. 

The scientists can now provide a general explanation for this phenomenon. With the help of a mathematical model, they can calculate how previous stimuli affect the current estimate. "The influence of prior experience most probably follows a general principle, and is likely to hold true for the estimation of quantities or sound levels also," says Glasauer. Test subjects whose distance estimates were strongly influenced by prior experience also placed greater weight on prior experience when asked to assess angular displacements. In both cases, they were learning without having received any information about the success or failure of their previous performance. Conventional learning methods, however, presuppose such feedback mechanisms. 

Whether or not a fundamental principle determines the perception of stimulus strengths, such as sound levels, brightness, or even distances, has been a controversial issue. Two important laws of psychophysics, the so-called Weber-Fechner law, published 150 years ago, and the 50-year-old Stevens' power law, seemed to contradict each other. The Munich scientists have now shown that the two laws are in fact compatible, at least for certain cases. By combining the Weber-Fechner law with Bayes' Theorem (1763), a procedure from probability theory that allows evidence to be weighted, they were able to transform it into Stevens' power law. Glasauer is therefore confident that "we have contributed to solving a problem that perception researchers have been studying for more than 50 years now." Next, the researchers want to analyze historical data and determine whether the model also applies to different stimulus modalities, such as sound levels and brightness. 

Source: Ludwig-Maximilians-Universität München [November 25, 2011]

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Nerve cells key to making sense of our senses

The human brain is bombarded with a cacophony of information from the eyes, ears, nose, mouth and skin. Now a team of scientists at the University of Rochester, Washington University in St. Louis, and Baylor College of Medicine has unraveled how the brain manages to process those complex, rapidly changing, and often conflicting sensory signals to make sense of our world. 

The answer lies in a relatively simple computation performed by single nerve cells, an operation that can be described mathematically as a straightforward weighted average. The key is that the neurons have to apply the correct weights to each sensory cue, and the authors reveal how this is done. 

The study, to be published online Nov. 20 in Nature Neuroscience, represents the first direct evidence of how the brain combines multiple sources of sensory information to form as accurate a perception as possible of its environment, the researchers report. 

The discovery may eventually lead to new therapies for people with Alzheimer's disease and other disorders that impair a person's sense of self-motion, says study coauthor Greg DeAngelis, professor and chair of brain and cognitive sciences at the University of Rochester. This deeper understanding of how brain circuits combine different sensory cues could also help scientists and engineers to design more sophisticated artificial nervous systems such as those used in robots, he adds. 

The brain is constantly confronted with changing and conflicting sensory input, says DeAngelis. For example, during IMAX theater footage of an aircraft rolling into a turn "you may find yourself grabbing the seat," he says. The large visual input makes you feel like you are moving, but the balance cues conveyed by sensors in your inner ear indicate that your body is in fact safely glued to the theater seat. So how does your brain decide how to interpret these conflicting inputs?

The study shows that the brain does not have to first "decide" which sensory cue is more reliable. "Indeed, this is what's exciting about what we have shown," says DeAngelis. The study demonstrates that the low-level computations performed by single neurons in the brain, when repeated by millions of neurons performing similar computations, accounts for the brain's complex ability to know which sensory signals to weight as more important. "Thus, the brain essentially can break down a seemingly high-level behavioral task into a set of much simpler operations performed simultaneously by many neurons," explains DeAngelis. 

The study confirms and extends a computational theory developed earlier by brain and cognitive scientist Alexandre Pouget at the University of Rochester and the University of Geneva, Switzerland and a coauthor on the paper. The theory predicted that neurons fire in a manner predicted by a weighted summation rule, which was largely confirmed by the neural data. Surprisingly, however, the weights that the neurons learned were slightly off target from the theoretical predictions, and the difference could explain why behavior also varies slightly from subject to subject, the authors conclude. "Being able to predict these small discrepancies establishes an exciting connection between computations performed at the level of single neurons and detailed aspects of behavior," says DeAngelis. 

To gather the data, the researchers designed a virtual-reality system to present subjects with two directional cues, a visual pattern of moving dots on a computer screen to simulate traveling forward and physical movement of the subject created by a platform. The researchers varied the amount of randomness in the motion of the dots to change how reliable the visual cues were relative to the motion of the platform. At the end of each trial, subjects indicated which direction they were heading, to the right or to the left.  

Source: University of Rochester [November 20, 2011]

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