Posts tagged decision making
Articles and news from the latest research reports.
Human Decision Making Based on Variations in Internal Noise: An EEG Study
Perceptual decision making is prone to errors, especially near threshold. Physiological, behavioural and modeling studies suggest this is due to the intrinsic or ‘internal’ noise in neural systems, which derives from a mixture of bottom-up and top-down sources. We show here that internal noise can form the basis of perceptual decision making when the external signal lacks the required information for the decision. We recorded electroencephalographic (EEG) activity in listeners attempting to discriminate between identical tones. Since the acoustic signal was constant, bottom-up and top-down influences were under experimental control. We found that early cortical responses to the identical stimuli varied in global field power and topography according to the perceptual decision made, and activity preceding stimulus presentation could predict both later activity and behavioural decision. Our results suggest that activity variations induced by internal noise of both sensory and cognitive origin are sufficient to drive discrimination judgments.
Decision Making: From Neuroscience to Psychiatry
Adaptive behaviors increase the likelihood of survival and reproduction and improve the quality of life. However, it is often difficult to identify optimal behaviors in real life due to the complexity of the decision maker’s environment and social dynamics. As a result, although many different brain areas and circuits are involved in decision making, evolutionary and learning solutions adopted by individual decision makers sometimes produce suboptimal outcomes. Although these problems are exacerbated in numerous neurological and psychiatric disorders, their underlying neurobiological causes remain incompletely understood. In this review, theoretical frameworks in economics and machine learning and their applications in recent behavioral and neurobiological studies are summarized. Examples of such applications in clinical domains are also discussed for substance abuse, Parkinson’s disease, attention-deficit/hyperactivity disorder, schizophrenia, mood disorders, and autism. Findings from these studies have begun to lay the foundations necessary to improve diagnostics and treatment for various neurological and psychiatric disorders.
Bad decisions arise from faulty information, not faulty brain circuits
Making decisions involves a gradual accumulation of facts that support one choice or another. A person choosing a college might weigh factors such as course selection, institutional reputation and the quality of future job prospects.
But if the wrong choice is made, Princeton University researchers have found that it might be the information rather than the brain’s decision-making process that is to blame. The researchers report in the journal Science that erroneous decisions tend to arise from errors, or “noise,” in the information coming into the brain rather than errors in how the brain accumulates information.
These findings address a fundamental question among neuroscientists about whether bad decisions result from noise in the external information — or sensory input — or because the brain made mistakes when tallying that information. In the example of choosing a college, the question might be whether a person made a poor choice because of misleading or confusing course descriptions, or because the brain failed to remember which college had the best ratings.
Previous measurements of brain neurons have indicated that brain functions are inherently noisy. The Princeton research, however, separated sensory inputs from the internal mental process to show that the former can be noisy while the latter is remarkably reliable, said senior investigator Carlos Brody, a Princeton associate professor of molecular biology and the Princeton Neuroscience Institute (PNI), and a Howard Hughes Medical Institute Investigator.
"To our great surprise, the internal mental process was perfectly noiseless. All of the imperfections came from noise in the sensory processes," Brody said. Brody worked with first author Bingni Brunton, now a postdoctoral research associate in the departments of biology and applied mathematics at the University of Washington; and Matthew Botvinick, a Princeton associate professor of psychology and PNI.
The research subjects — four college-age volunteers and 19 laboratory rats — listened to streams of randomly timed clicks coming into both the left ear and the right ear. After listening to a stream, the subjects had to choose the side from which more clicks originated. The rats had been trained to turn their noses in the direction from which more clicks originated.
The test subjects mostly chose the correct side but occasionally made errors. By comparing various patterns of clicks with the volunteers’ responses, researchers found that all of the errors arose when two clicks overlapped, and not from any observable noise in the brain system that tallied the clicks. This was true in experiment after experiment utilizing different click patterns, in humans and rats.
The researchers used the timing of the clicks and the decision-making behavior of the test subjects to create computer models that can be used to indicate what happens in the brain during decision-making. The models provide a clear window into the brain during the “mulling over” period of decision-making, the time when a person is accumulating information but has yet to choose, Brody said.
"Before we conducted this study, we did not have a way of looking at this process without inserting electrodes into the brain," Brody said. "Now thanks to our model, we have an estimation of what is going on at each moment in time during the formation of the decision."
The study suggests that information represented and processed in the brain’s neurons must be robust to noise, Brody said. “In other words, the ‘neural code’ may have a mechanism for inherent error correction,” he said.
"The new work from the Brody lab is important for a few reasons," said Anne Churchland, an assistant professor of biological sciences at Cold Spring Harbor Laboratory who studies decision-making and was not involved in the study. "First, the work was very innovative because the researchers were able to study carefully controlled decision-making behavior in rodents. This is surprising in that one might have guessed rodents were incapable of producing stable, reliable decisions that are based on complex sensory stimuli.
"This work exposed some unexpected features of why animals, including humans, sometimes make incorrect decisions," Churchland said. "Specifically, the researchers found that errors are mostly driven by the inability to accurately encode sensory information. Alternative possibilities, which the authors ruled out, included noise associated with holding the stimulus in mind, or memory noise, and noise associated with a bias toward one alternative or the other."
(Source: princeton.edu)
Punishment can enhance performance
The stick can work just as well as the carrot in improving our performance, a team of academics at The University of Nottingham has found.
A study led by researchers from the University’s School of Psychology, published recently in the Journal of Neuroscience, has shown that punishment can act as a performance enhancer in a similar way to monetary reward.
Dr Marios Philiastides, who led the work, said: “This work reveals important new information about how the brain functions that could lead to new methods of diagnosing neural development disorders such as autism, ADHD and personality disorders, where decision-making processes have been shown to be compromised.”
The Nottingham study aimed at looking at how the efficiency with which we make decisions based on ambiguous sensory information — such as visual or auditory — is affected by the potential for, and severity of, anticipated punishment.
Imposing penalties
To investigate this, they asked participants in the study to perform a simple perceptual task — asking them to judge whether a blurred shape behind a rainy window is a person or something else.
They punished incorrect decisions by imposing monetary penalties. At the same time, they measured the participants’ brain activity in response to different amounts of monetary punishment. Brain activity was recorded, non-invasively, using an EEG machine which detects and amplifies brain signals from the surface of the scalp through a set of small electrodes embedded in a swim-like cap fitted on the participants’ head.
They found that participants’ performance increased systematically as the amount of punishment increased, suggesting that punishment acts as a performance enhancer in a similar way to monetary reward.
At the neural level, the academics identified multiple and distinct brain activations induced by punishment and distributed throughout different areas of the brain. Crucially, the timing of these activations confirmed that the punishment does not influence the way in which the brain processes the sensory evidence but does have an impact on the brain’s decision maker responsible for decoding sensory information at a later stage in the decision-making process.
Incentive-based motivation
Finally, they showed that those participants who showed the greatest improvements in performance also showed the biggest changes in brain activity. This is a key finding as it provides a potential route to study differences between individuals and their personality traits in order to characterise why some may respond better to reward and punishment than others.
A more thorough understanding of the influence of punishment on decision-making and how we make choices could lead to useful information on how to use incentive-based motivation to encourage certain behaviour.
The paper, Temporal Characteristics of the Influence of Punishment on Perceptual Decision Making in the Human Brain, is available online via the Journal of Neuroscience.
!['I don't want to pick!' Preschoolers know when they aren't sure
Children as young as 3 years old know when they are not sure about a decision, and can use that uncertainty to guide decision making, according to new research from the Center for Mind and Brain at the University of California, Davis.
"There is behavioral evidence that they can do this, but the literature has assumed that until late preschool, children cannot introspect and make a decision based on that introspection," said Simona Ghetti, professor of psychology at UC Davis and co-author of the study with graduate student Kristen Lyons, now an assistant professor at Metropolitan State University of Denver. [Preschoolers Use Introspection to Make Decisions]
The findings are published online by the journal Child Development and will appear in print in an upcoming issue.
Ghetti studies how reasoning, memory and cognition emerge during childhood. It is known that children get better at introspection through elementary school, she said. Lyons and Ghetti wanted to see whether this ability to ponder exists in younger children.
Previous studies have used open-ended questions to find out how children feel about a decision, but that approach is limited by younger children’s ability to report on the content of their mental activity. Instead, Lyons and Ghetti showed 3-, 4- and 5-year-olds ambiguous drawings of objects and asked them to point to a particular object, such as a cup, a car or the sun. Then they asked the children to point to one of two pictures of faces, one looking confident and one doubtful, to rate whether they were confident or not confident about a decision.
In one of the tests, children had to choose a drawing even if unsure. In a second set of tests they had a “don’t want to pick” option.
Across the age range, children were more likely to say they were not confident about their decision when they had in fact made a wrong choice. When they had a “don’t know” option, they were most likely to take it if they had been unsure of their choice in the “either/or” test.
By opting not to choose when uncertain, the children could improve their overall accuracy on the test.
"Children as young as 3 years of age are aware of when they are making a mistake, they experience uncertainty that they can introspect on, and then they can use that introspection to drive their decision making," Ghetti said.
The researchers hope to extend their studies to younger children to examine the emergence of introspection and reasoning.
(Image: Jupiter Images)](http://40.media.tumblr.com/aa8c41046567c1d2b43a5fb0208cc4ea/tumblr_mjljxnVatw1rog5d1o1_500.jpg)
'I don't want to pick!' Preschoolers know when they aren't sure
Children as young as 3 years old know when they are not sure about a decision, and can use that uncertainty to guide decision making, according to new research from the Center for Mind and Brain at the University of California, Davis.
"There is behavioral evidence that they can do this, but the literature has assumed that until late preschool, children cannot introspect and make a decision based on that introspection," said Simona Ghetti, professor of psychology at UC Davis and co-author of the study with graduate student Kristen Lyons, now an assistant professor at Metropolitan State University of Denver. [Preschoolers Use Introspection to Make Decisions]
The findings are published online by the journal Child Development and will appear in print in an upcoming issue.
Ghetti studies how reasoning, memory and cognition emerge during childhood. It is known that children get better at introspection through elementary school, she said. Lyons and Ghetti wanted to see whether this ability to ponder exists in younger children.
Previous studies have used open-ended questions to find out how children feel about a decision, but that approach is limited by younger children’s ability to report on the content of their mental activity. Instead, Lyons and Ghetti showed 3-, 4- and 5-year-olds ambiguous drawings of objects and asked them to point to a particular object, such as a cup, a car or the sun. Then they asked the children to point to one of two pictures of faces, one looking confident and one doubtful, to rate whether they were confident or not confident about a decision.
In one of the tests, children had to choose a drawing even if unsure. In a second set of tests they had a “don’t want to pick” option.
Across the age range, children were more likely to say they were not confident about their decision when they had in fact made a wrong choice. When they had a “don’t know” option, they were most likely to take it if they had been unsure of their choice in the “either/or” test.
By opting not to choose when uncertain, the children could improve their overall accuracy on the test.
"Children as young as 3 years of age are aware of when they are making a mistake, they experience uncertainty that they can introspect on, and then they can use that introspection to drive their decision making," Ghetti said.
The researchers hope to extend their studies to younger children to examine the emergence of introspection and reasoning.
(Image: Jupiter Images)
Neuro-magic: Magician uses magic tricks to study the brain’s powers of perception and memory
A magician is using his knowledge of magic theory and practice to investigate the brain’s powers of observation.
Hugo Caffaratti, engineer and semi-professional magician from Barcelona, Spain, has embarked on a PhD with the University of Leicester’s Centre for Systems Neuroscience.
Hugo has 12 years of experience working with magic – specialising in card tricks – and is a member of the Spanish Society of Illusionism (SEI-ACAI).
The engineer also has a longstanding interest in neuroscience and bioengineering, having taken a Master’s degree in Biomedical Engineering at University of Barcelona.
He hopes to combine his two interests in his PhD thesis project, which covers a new field of Cognitive Neuroscience: Neuro-Magic.
As part of his work, he will investigate how our brains perceive what actually happens before our eyes – and how our attention can be drawn away from important details.
He also plans to study “forced choice” - a tool often used by magicians where we are fooled into thinking we have made a free choice.
Among other experiments, Hugo will ask participants to watch videos of card trick performances, while sitting in front of an eye-tracker device.
This will allow him to monitor where our attention is focused during illusions – and how our brain can be deceived when our eyes miss the whole picture.
Hugo said: “I have always been interested in the study of the brain. It is amazing to be involved in the process of combining the disciplines of neuroscience and magic.
“I am really interested in the fields of decision making and forced-choice. It is incredible that many times a day we make a decision and feel free. We do not realise that we have been forced to make that decision.
“I am constructing an experiment to study what happens when we make forced decisions – to try and find the reasons for it. I am thinking about which kinds of tricks I know could be useful to give more insights about brain function.”
He will work under the tutelage of Professor Rodrigo Quian Quiroga, director of the Centre for Systems Neuroscience.
Professor Quian Quiroga’s recent work on memory formation was the topic of his recent book “Borges and memory” (MIT Press) and was also featured on the front page of the international science publication Scientific American.
Professor Rodrigo Quian Quiroga said: “I am very interested in connections between science and the arts. Last year, for example, we organized an art and science exhibition as a result of a 1-year rotation in my lab of visual artist Mariano Molina. Hugo’s PhD will look at decision-making and attention – and although he is doing his first steps in neuroscience, I think he already has a lot of expertise in this area based on his training as a magician.
“Magic theory has thousands of years of experience. Magicians have been answering similar questions that we have in the lab, and they have an intuitive knowledge of how the mind works. Hugo will likely bring a fresh new view on how to address questions we deal with in neuroscience.”
Hugo is also keen to carry on with his work in magic while studying for his PhD, and is hoping to perform in bars in Leicester while staying here.
He has also applied for membership with The Magic Circle – a prestigious magic society of London. He will have to sit exams to prove his magical mettle in order to join the exclusive club.
The Role of Medial Prefrontal Cortex in Memory and Decision Making
Some have claimed that the medial prefrontal cortex (mPFC) mediates decision making. Others suggest mPFC is selectively involved in the retrieval of remote long-term memory. Yet others suggests mPFC supports memory and consolidation on time scales ranging from seconds to days. How can all these roles be reconciled? We propose that the function of the mPFC is to learn associations between context, locations, events, and corresponding adaptive responses, particularly emotional responses. Thus, the ubiquitous involvement of mPFC in both memory and decision making may be due to the fact that almost all such tasks entail the ability to recall the best action or emotional response to specific events in a particular place and time. An interaction between multiple memory systems may explain the changing importance of mPFC to different types of memories over time. In particular, mPFC likely relies on the hippocampus to support rapid learning and memory consolidation.
Researchers demonstrate that a saliva analysis can reveal decision-making skills
A study conducted by researchers at the University of Granada Group of Neuropsychology and Clinical Psychoneuroimmunology has demonstrated that cortisol levels in saliva are associated with a person’s ability to make good decisions in stressful situations.
To perform this study, the researchers exposed the participants (all women) to a stressful situation by using sophisticated virtual reality technology. The study revealed that people who are not skilled in decision-making have lower baseline cortisol levels in saliva as compared to skilled people.
Cortisol –known as the stress hormone– is a steroid hormone segregated at the adrenal cortex and stimulated by the adrenocorticotropic (ACTH) hormone, which is produced at the pituitary gland. Cortisol is involved in a number of body systems and plays a relevant role in the muscle-skeletal system, blood circulation, the immune system, the metabolism of fats, carbohydrates and proteins and the nervous system.
Recent studies have demonstrated that stress can influence decision making in people. This cognitive component might be considered one of the human resources for coping with stress.
The Power of Music: Mind Control by Rhythmic Sound
You walk into a bar and music is thumping. All heads are bobbing and feet tapping in synchrony. Somehow the rhythmic sound grabs control of the brains of everyone in the room forcing them to operate simultaneously and perform the same behaviors in synchrony. How is this possible? Is this unconscious mind control by rhythmic sound only driving our bodily motions, or could it be affecting deeper mental processes?
The mystery runs deeper than previously thought, according to psychologist Annett Schirmer reporting new findings today at the Society for Neuroscience meeting in New Orleans. Rhythmic sound “not only coordinates the behavior of people in a group, it also coordinates their thinking—the mental processes of individuals in the group become synchronized.”
This finding extends the well-known power of music to tap into brain circuits controlling emotion and movement, to actually control the brain circuitry of sensory perception. This discovery helps explain how drums unite tribes in ceremony, why armies march to bugle and drum into battle, why worship and ceremonies are infused by song, why speech is rhythmic, punctuated by rhythms of emphasis on particular syllables and words, and perhaps why we dance.
New findings illuminate basis in brain for social decisions, reactions
The social brain consists of the structures and circuits that help people understand others’ intentions, beliefs, and desires, and how to behave appropriately. Its smooth functioning is essential to humans’ ability to cooperate. Its dysfunction is implicated in a range of disorders, from autism, to psychopathology, to schizophrenia.
New findings show that:
• Primates employ three different parts of the prefrontal cortex in decisions about whether to give or keep prized treats. These findings illuminate a poorly understood brain circuit, and offer possible insights into human sharing and other social behavior (Steve Chang, PhD, abstract 129.10).
• Different brain regions are engaged in altruistic behavior that is motivated by genuine caring versus altruistic behavior motivated by a concern for reputation or self-image (Cendri Hutcherson, PhD, abstract 129.06).
• The experience of racial discrimination triggers activity in the same brain regions that respond to pain, social rejection, and other stressful experiences (Arpana Gupta, PhD, abstract 402.06).Another recent finding discussed shows that:
• Competition against a human opponent or a computer engages the same parts of the brain, with one exception: the temporal parietal junction is used to predict only a human’s upcoming actions (Ronald Carter, PhD).