Archive for September 2009
Reading a book by Franz Kafka –– or watching a film by director David Lynch –– could make you smarter.
According to research by psychologists at UC Santa Barbara and the University of British Columbia, exposure to the surrealism in, say, Kafka’s “The Country Doctor” or Lynch’s “Blue Velvet” enhances the cognitive mechanisms that oversee implicit learning functions. “The idea is that when you’re exposed to a meaning threat –– something that fundamentally does not make sense –– your brain is going to respond by looking for some other kind of structure within your environment,” said Travis Proulx, a postdoctoral researcher at UCSB and co-author of the article. “And, it turns out, that structure can be completely unrelated to the meaning threat.”
Meaning, according to Proulx, is an expected association within one’s environment. Fire, for example, is associated with extreme heat, and putting your hand in a flame and finding it icy cold would constitute a threat to that meaning. “It would be very disturbing to you because it wouldn’t make sense,” he said.
As part of their research, Proulx and Steven J. Heine, a professor of psychology at the University of British Columbia and the article’s second co-author, asked a group of subjects to read an abridged and slightly edited version of Kafka’s “The Country Doctor,” which involves a nonsensical –– and in some ways disturbing –– series of events. A second group read a different version of the same short story, one that had been rewritten so that the plot and literary elements made sense. The subjects were then asked to complete an artificial-grammar learning task in which they were exposed to hidden patterns in letter strings. They were asked to copy the individual letter strings and then to put a mark next to those that followed a similar pattern.
“People who read the nonsensical story checked off more letter strings –– clearly they were motivated to find structure,” said Proulx. “But what’s more important is that they were actually more accurate than those who read the more normal version of the story. They really did learn the pattern better than the other participants did.”
In a second study, the same results were evident among people who were led to feel alienated about themselves as they considered how their past actions were often contradictory. “You get the same pattern of effects whether you’re reading Kafka or experiencing a breakdown in your sense of identity,” Proulx explained. “People feel uncomfortable when their expected associations are violated, and that creates an unconscious desire to make sense of their surroundings. That feeling of discomfort may come from a surreal story, or from contemplating their own contradictory behaviors, but either way, people want to get rid of it. So they’re motivated to learn new patterns.”
Thus far, the researchers have identified the beneficial effects of unusual experiences only in implicit pattern learning. It remains to be seen whether or not reading surreal literature would aid in the learning of studied material as well. “It’s important to note that sitting down with a Kafka story before exam time probably wouldn’t boost your performance on a test,” said Proulx.
“What is critical here is that our participants were not expecting to encounter this bizarre story,” he continued. “If you expect that you’ll encounter something strange or out of the ordinary, you won’t experience the same sense of alienation. You may be disturbed by it, but you won’t show the same learning ability. The key to our study is that our participants were surprised by the series of unexpected events, and they had no way to make sense of them. Hence, they strived to make sense of something else.”
Volume 20, Issue 9, Date: September 2009, Pages: 1125-1131
Connections From Kafka: Exposure to Meaning Threats Improves Implicit Learning of an Artificial Grammar
Travis Proulx, Steven J. Heine
ABSTRACT—In the current studies, we tested the prediction that learning of novel patterns of association would be enhanced in response to unrelated meaning threats. This prediction derives from the meaning-maintenance model, which hypothesizes that meaning-maintenance efforts may recruit patterns of association unrelated to the original meaning threat. Compared with participants in control conditions, participants exposed to either of two unrelated meaning threats (i.e., reading an absurd short story by Franz Kafka or arguing against one’s own self-unity) demonstrated both a heightened motivation to perceive the presence of patterns within letter strings and enhanced learning of a novel pattern actually embedded within letter strings (artificial-grammar learning task). These results suggest that the cognitive mechanisms responsible for implicitly learning patterns are enhanced by the presence of a meaning threat.
Bring water, bring wine, boy,
Bring us wreaths of flowers:
With Eros I don’t want to fight.
… Anakreon had it in the 6th century B. C. Praise the wine before drinking it!
Psychosocial factors are bound to play a role when it comes to its taste: indeed, scientists do not exclude the possibility that avid wine drinkers and connoisseurs might change their opinion, and therefore their rating, afterwards to save face. This issue should be examined in more detail in future studies. For now, however, the scientists have a practical tip for restaurants and hosts: always stress the quality of the wine before it is tasted!Wine tastes different to those who are given information on the product before a wine tasting, tests where the test people received information on the wine before and after the tasting have shown.
Many a wine grower trembles at the prospect of a visit from Robert Parker, one of the most famous wine critics in the world. His “Parker Points” have a similar impact to the Roman Emperor’s thumb, deciding the success of a winery instead of life and death. The extent to which product information like Parker’s ratings influence the consumer is revealed in a study by Michael Siegrist, Professor of Consumer Behavior at the Institute for Environmental Decisions, and his post-doc Marie-Eve Cousin from ETH Zurich.
The two scientists wanted to find out how information of that type influences the sensory experience by testing their hypothesis that the wine critic’s opinion affects the sense of taste – and not just the rating.
Good and bad information
163 test people tasted the Argentinean red wine “Clos de Los Siete Mendoza” (2006), which Robert Parker had given 92 points out of 100 and thus had rated as an exceptional wine. The two scientists divided the subjects into five groups: one was told about Parker’s positive appraisal before the tasting; the second group also received the information beforehand, but was told that the wine had only scored 72 Parker Points and was thus average. Two more groups received the positive or negative information after they had tasted the wine but before they had rated it themselves. The final group was not given any information at all and served as the control group.
The test people, who tasted the wine separately, were asked to rate the wine on a 10-point scale, ranging from “didn’t like it at all” to “excellent”. They were also supposed to state how much they would be prepared to pay for the wine.
Advance information influences senses
The analysis of the test results revealed that the test people who had been given the ratings with 92 or 72 points before the tasting rated the wine differently to those who weren’t given the Parker rating until afterwards. In the first two groups, the test people who had been given negative information rated the wine considerably worse than those who proceeded on the assumption that the wine was good. Those who knew beforehand that the wine had been given 92 Parker Points also found the wine better than those who only discovered the rating after they had tried the wine.
The information not only influences the sense of taste, but also how deep we are prepared to dig into our wallets: again, the test people with negative advance information were prepared to pay the least.
The researchers feel their initial hypothesis has been confirmed and conclude that the opinions of wine critics do have an impact on a wine drinker’s sense of taste. Surprisingly, the subjects did not change their opinion if they received the information after tasting. “People therefore were not simply trying to show themselves in a good light; the information really did alter their sense of taste”, says Siegrist.
So it what remains of Parker’s opinions then, if he himself is, as one might assume, more influenced by the marketing informations that drown him? Better taste your own…
Appetite Volume 52, Issue 3, June 2009, Pages 762-765
Expectations influence sensory experience in a wine tasting
References and further reading may be available for this article. To view references and further reading you must purchase this article.
Michael Siegrist (a, Corresponding Author Contact Information, E-mail The Corresponding Author and Marie-Eve Cousin (b, E-mail The Corresponding Author
a ETH Zurich, Institute for Environmental Decisions (IED), Consumer Behavior, Universitätsstrasse 22, CHN J76.3, CH-8092 Zurich, Switzerland
b ETH Zurich, Institute for Environmental Decisions (IED), Consumer Behavior, Universitätsstrasse 22, CHN H75.3, CH-8092 Zurich, Switzerland
AbstractInformation about a product may shape consumers’ taste experience. In a wine tasting experiment, participants received (positive or negative) information about the wine prior to or after the tasting. When the information was given prior to the tasting, negative information about the wine resulted in lower ratings compared to the group that received positive information. No such effect was observed when participants received the information after the tasting but before they evaluated the wine. Results suggest that the information about the wine affected the experience itself and not only participants’ overall assessment of the wine after the tasting.
Keywords: Sensory evaluation; Taste; Perception; Consumer experience
A woman looks familiar, but you can’t remember her name or where you met her. New research by UC Irvine neuroscientists suggests the memory exists – you simply can’t retrieve it.
Using advanced brain imaging techniques, the scientists discovered that a person’s brain activity while remembering an event is very similar to when it was first experienced, even if specifics can’t be recalled.
“If the details are still there, hopefully we can find a way to access them,” said Jeff Johnson, postdoctoral researcher at UCI’s Center for the Neurobiology of Learning & Memory and lead author of the study, appearing Sept. 10 in the journal Neuron.
“By understanding how this works in young, healthy adults, we can potentially gain insight into situations where our memories fail more noticeably, such as when we get older,” he said. “It also might shed light on the fate of vivid memories of traumatic events that we may want to forget.”
In collaboration with scientists at Princeton University, Johnson and colleague Michael Rugg, CNLM director, used functional magnetic resonance imaging to study the brain activity of students.
Inside an fMRI scanner, the students were shown words and asked to perform various tasks: imagine how an artist would draw the object named by the word, think about how the object is used, or pronounce the word backward in their minds. The scanner captured images of their brain activity during these exercises.
About 20 minutes later, the students viewed the words a second time and were asked to remember any details linked to them. Again, brain activity was recorded.
Utilizing a mathematical method called pattern analysis, the scientists associated the different tasks with distinct patterns of brain activity. When a student had a strong recollection of a word from a particular task, the pattern was very similar to the one generated during the task. When recollection was weak or nonexistent, the pattern was not as prominent but still recognizable as belonging to that particular task.
“The pattern analyzer could accurately identify tasks based on the patterns generated, regardless of whether the subject remembered specific details,” Johnson said. “This tells us the brain knew something about what had occurred, even though the subject was not aware of the information.”
However valuable these results are, they seem to be missing half of the picture. At least in the amygdala, a brain structure involved in emotional control, scanning for neuronal activity would not be enough in order to trap the building of memory. Next to neurons themselves, their embedding matrix too is involved in memory protection and recollection.
Neuron, Volume 63, Issue 5, 697-708, 10 September 2009
Recollection, Familiarity, and Cortical Reinstatement: A Multivoxel Pattern Analysis
Jeffrey D. Johnson1, 4, Go To Corresponding Author, , Susan G.R. McDuff2, 4, Michael D. Rugg1 and Kenneth A. Norman2, 3
1 Center for the Neurobiology of Learning and Memory and Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA 92697, USA
2 Department of Psychology, Princeton University, Princeton, NJ 08544, USA
3 Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA
4 These authors contributed equally to this work.
SummaryEpisodic memory retrieval is thought to involve reinstatement of the neurocognitive processes engaged when an episode was encoded. Prior fMRI studies and computational models have suggested that reinstatement is limited to instances in which specific episodic details are recollected. We used multivoxel pattern-classification analyses of fMRI data to investigate how reinstatement is associated with different memory judgments, particularly those accompanied by recollection versus a feeling of familiarity (when recollection is absent). Classifiers were trained to distinguish between brain activity patterns associated with different encoding tasks and were subsequently applied to recognition-related fMRI data to determine the degree to which patterns were reinstated. Reinstatement was evident during both recollection- and familiarity-based judgments, providing clear evidence that reinstatement is not sufficient for eliciting a recollective experience. The findings are interpreted as support for a continuous, recollection-related neural signal that has been central to recent debate over the nature of recognition memory processes.
Science 4 September 2009: Vol. 325. no. 5945, pp. 1258 – 1261
Perineuronal Nets Protect Fear Memories from Erasure
Nadine Gogolla, Pico Caroni, Andreas Lüthi, Cyril Herry
In adult animals, fear conditioning induces a permanent memory that is resilient to erasure by extinction. In contrast, during early postnatal development, extinction of conditioned fear leads to memory erasure, suggesting that fear memories are actively protected in adults. We show here that this protection is conferred by extracellular matrix chondroitin sulfate proteoglycans (CSPGs) in the amygdala. The organization of CSPGs into perineuronal nets (PNNs) coincided with the developmental switch in fear memory resilience. In adults, degradation of PNNs by chondroitinase ABC specifically rendered subsequently acquired fear memories susceptible to erasure. This result indicates that intact PNNs mediate the formation of erasure-resistant fear memories and identifies a molecular mechanism closing a postnatal critical period during which traumatic memories can be erased by extinction.
It would be difficult to find someone who has never felt shame in their life.
Shame is a common reaction when someone feels that they have fallen below social norms or their own standards. From being intoxicated in front of one’s peers and superiors to failing an important test at school or being rejected at the school dance, shame can be an internal alarm that ensures that we know when we are at risk of finding ourselves outside the lines of societal acceptance and desirability.
University of Alberta researcher Jessica Van Vliet’s study, published in the British Psychological Society journal, Psychology and Psychotherapy: Theory, Research, and Practice, indicates that, while it may seem difficult when one is stuck in shame, there is hope for moving beyond this painful emotion.
“Shame can prompt us to make changes that will help protect our relationships and also preserve the fabric of society. It’s important to emphasize that shame is essential and has value,” said Van Vliet. “The problem is when people get paralyzed with shame and withdraw from others. Not only can this create mental-health problems for people, but also they no longer contribute as fully to society.”
Van Vliet’s research shows that people who feel debilitated by shame tend to internalize and over-personalize the situation. They also seem resigned to being unable to change their feelings or their fate.
“When people experience shame, they may say to themselves ‘I’m to blame, it’s all my fault, all of me is bad, and there’s nothing I can do to change the situation,'” said Van Vliet. “They identify so much with shame that it takes over their entire view of themselves. That leads to an overwhelming feeling of powerlessness.”
Van Vliet notes that one of the key components to overcoming these feelings is to step back from the problem and view the picture in a different light. When sufferers can identify external factors that contributed to their actions or situation (for example, discrimination or peer pressure) and differentiate between being a bad person versus doing something bad, they can begin to break the grip of hopelessness that plagues them.
“When people move from a sense of uncontrollability to the belief that maybe there’s something they can do about their situation, such as apologizing or making amends for their actions, it starts increasing a sense of hope for the future,” she said.
Van Vliet found that one of the key steps to overcoming a profound sense of shame is making connections, be it with family and friends, a higher power, or humanity as a whole. While it is one of several aspects of moving forward, Van Vliet notes that the step can often blend or lead into others.
“Connecting to others helps to increase self-acceptance, and with self-acceptance can come a greater acceptance of other people as well,” said Van Vliet. “People start to realize that it’s not just them. Other people do things that are as bad or even worse sometimes so they’re not the worst person on the planet. They start to say to themselves, ‘This is human, I am human, others are human.'”
Psychology and Psychotherapy: Theory, Research and Practice, Volume 82, Number 2, June 2009 , pp. 137-152(16) DOI: 10.1348/147608308X389391
The role of attributions in the process of overcoming shame: A qualitative analysis
Van Vliet, K. Jessica1
Affiliations: 1: University of Alberta, Edmonton, Alberta, Canada
Objectives:While attributions have been found to play an important role in the experience of shame, little is currently known about attributions that occur as part of shame reparation. This exploratory study investigated the attributions associated with recovery from shame, based on the perspectives of participants.
Design:Grounded theory was used in data collection and analysis. This approach has been used extensively for developing understandings of how people construct meaning, interpret events, and act on the basis of their beliefs and interpretations.
Methods:The participants were nine women and four men between the ages of 24 and 70. Data came from interviews in which the participants recalled a distressing shame experience and described how they recovered. Emphasis was on the participants’ subjective perspectives, meanings, and interpretations.
Results:Shame involved global and stable dispositional attributions where the entire self was regarded as flawed and unattractive, and participants perceived themselves as powerless to change an unwanted identity. Internal causal attributions and self-blame were present in most but not all shame experiences. Recovery involved a movement towards specific and unstable attributions that enhanced self-concept and maximized a sense of power and control over the future. Shared and external factors that contributed to the event were also identified.
Conclusions:When applied to psychotherapy for shame-related distress, these findings point to the importance of exploring clients’ attributions related to specific shame events and using interventions that promote attributional change. Directions for further research are discussed.
Medically, crying is known to be a symptom of physical pain or stress. But now a Tel Aviv University evolutionary biologist looks to empirical evidence showing that tears have emotional benefits and can make interpersonal relationships stronger.
New analysis by Dr. Oren Hasson of TAU’s Department of Zoology shows that tears still signal physiological distress, but they also function as an evolution-based mechanism to bring people closer together.
“Crying is a highly evolved behavior,” explains Dr. Hasson. “Tears give clues and reliable information about submission, needs and social attachments between one another. My research is trying to answer what the evolutionary reasons are for having emotional tears.
“My analysis suggests that by blurring vision, tears lower defences and reliably function as signals of submission, a cry for help, and even in a mutual display of attachment and as a group display of cohesion,” he reports.
His research, published recently in Evolutionary Psychology, investigates the different kinds of tears we shed — tears of joy, sadness and grief — as well as the authenticity or sincerity of the tears. Crying, Dr. Hasson says, has unique benefits among friends and others in our various communities.
For crying out loud (and behind closed doors)
Approaching the topic with the deductive tools of an evolutionary biologist, Dr. Hasson investigated the use of tears in various emotional and social circumstances. Tears are used to elicit mercy from an antagonistic enemy, he claims. They are also useful in eliciting the sympathy — and perhaps more importantly the strategic assistance — of people who were not part of the enemy group.
“This is strictly human,” reasons Dr. Hasson. “Emotional tears also signal appeasement, a need for attachment in times of grief, and a validation of emotions among family, friends and members of a group.”
Crying enhances attachments and friendships, says Dr. Hasson, but taboos are still there in certain cases. In some cultures, societies or circumstances, the expression of emotions is received as a weakness and the production of tears is suppressed. For example, it is rarely acceptable to cry in front of your boss at work — especially if you are a man, he says.
Streets awash with tears?
Multiple studies across cultures show that crying helps us bond with our families, loved ones and allies, Dr. Hasson says. By blurring vision, tears reliably signal your vulnerability and that you love someone, a good evolutionary strategy to emotionally bind people closer to you.
“Of course,” Dr. Hasson adds, “the efficacy of this evolutionary behavior always depends on who you’re with when you cry those buckets of tears, and it probably won’t be effective in places, like at work, when emotions should be hidden.”
Dr. Hasson, a marriage therapist, uses his conclusions in his clinic. “It is important to legitimize emotional tears in relationships,” he says. “Too often, women who cry feel ashamed, silly or weak, when in reality they are simply connected with their feelings, and want sympathy and hugs from their partners.”
Evolutionary Psychology http://www.epjournal.net – 2009. 7(3): 363-370
Emotional Tears as Biological Signals
Biomathematics Unit, Department of Zoology, Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel. Email: email@example.com
Abstract: Emotional tears have been shown to enhance the interpretation of sadness that is inferred from facial expressions. The current paper puts emotional tears in an evolutionary context. By using biological signaling theory, it first looks at the distinction between cues and signals, both of which provide information to recipients, except that signals have evolved for that purpose. The conclusion is that a signaling function has yet to be shown. Nevertheless, as emotional tears are likely to function as signals, an analysis of certain inevitable effects of tears on the individual hint at more than a single signaling function, depending on the context in which tears are produced. Emotional tears decrease the perception of gaze direction or of changes in pupil size, and may function as attenuators of intentions. Emotional tears are more likely, however, to function as handicaps. By blurring vision, they handicap aggressive or defensive actions, and may function as reliable signals of appeasement, need or attachment.
Keywords: Emotions, tears, signaling, handicap, intentions.
A study in the Aug. 15 issue of the Journal of Clinical Sleep Medicine shows that the use of cognitive behavioral therapy for insomnia (CBT-I) is an effective treatment for older patients with osteoarthritis and comorbid insomnia.
Results showed that treatment improves both immediate and long-term self-reported sleep and pain in older patients with osteoarthritis and comorbid insomnia without directly addressing pain control. Participants who received CBT-I reported significantly decreased sleep latency (initially decreased by an average of 16.9 minutes and 11 minutes a year after treatment) and wake after sleep onset (initially decreased by an average of 37 minutes and 19.9 minutes a year after treatment), significantly reduced pain (initially improved by 9.7 points and 4.7 points a year after treatment) and increased sleep efficiency (initially increased by 13 percent and 8 percent a year after treatment). These improvements persisted in CBT-I patients (19 of 23) who were further assessed for sleep quality and perceived pain at a one-year follow-up visit.
According to lead author Michael V. Vitiello, PhD, professor at the University of Washington in Seattle, Wash., results indicate that insomnia is not merely a symptom of osteoarthritis but rather a co-existing illness. Vitiello said improving sleep can result in an improvement in osteoarthritis, which is particularly important because, at least in older adults, insomnia rarely exits by itself, rather it typically coexists with other illnesses, pain conditions and depression.
“The particular strength of CBT-I is that once an individual learns how to improve their sleep, study after study has shown that the improvement persists for a year or more,” said Vitiello. “What we and others are showing is that CBT-I can not only improve sleep but that improvement of sleep may lead to improvement in co-existing medical or psychiatric illnesses, such as osteoarthritis or depression, and in the case of our study, that these additional benefits can be seen in the long term.”
A total of 23 patients with a mean age of 69 years were randomly assigned to CBT-I, while 28 patients with a mean age of 66.5 years were assigned to a stress management and wellness control group. Participants in the control group reported no significant improvements in any measure.
CBT-I intervention consisted of eight weekly, two-hour classes ranging in size from four to eight participants. All classes were conducted in an academic medical center in downtown Chicago and were spread out over the calendar year. Participants received polysomnographic assessment in their home in order to exclude individuals with sleep apnea. Sleep and pain were assessed by self-report at baseline, after treatment, and (for CBT-I only) at one year follow-up. Sleep logs were recorded prior to and after treatment and at the one year follow-up and included information about sleep latency, wake after sleep onset and sleep efficiency. Subjects were required to be over the age of 55, have insomnia symptoms that have persisted for at least six months and have been diagnosed with osteoarthritis. A majority of the sample was female. Volunteers were recruited from placements of brochures, memos and flyers in places where medical patients who qualified for the study might see them.
According to the study, sleep quality is a major concern for people with osteoarthritis, with 60 percent of people who have the disease reporting pain during the night. Chronic pain initiates and exacerbates sleep disturbance; disturbed sleep in turn maintains and exacerbates chronic pain and related dysfunction.
The findings indicate that successful treatment of sleep disturbance may improve the quality of life for patients in this population. The authors recommend that CBT-I, which specifically targets sleep, be incorporated into behavioral interventions for pain management in osteoarthritis and possibly for other chronic pain conditions as well.
J Clin Sleep Med 2009;5:355-362.
Cognitive Behavioral Therapy for Insomnia Improves Sleep and Decreases Pain in Older Adults with Co-Morbid Insomnia and Osteoarthritis
Michael V. Vitiello, Ph.D.1; Bruce Rybarczyk, Ph.D.2; Michael Von Korff, Ph.D.3; Edward J. Stepanski, Ph.D.4
1Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA;
2Department of Psychology, Virginia Commonwealth University, Richmond, VA; 3Center for Health Studies, Group Health Cooperative of Puget Sound, Seattle, WA;
4Accelerated Community Oncology Research Network, Inc., Memphis, TN
Study Objectives: Osteoarthritis pain affects more than half of all older adults, many of whom experience co-morbid sleep disturbance. Pain initiates and exacerbates sleep disturbance, whereas disturbed sleep maintains and exacerbates pain, which implies that improving the sleep of patients with osteoarthritis may also reduce their pain. We examined this possibility in a secondary analysis of a previously published randomized controlled trial of cognitive behavioral therapy for insomnia (CBT-I) in patients with osteoarthritis and co-morbid insomnia.
Methods: Twenty-three patients (mean age 69.2 years) were randomly assigned to CBT-I and 28 patients (mean age 66.5 years) to an attention control. Neither directly addressed pain management. Twelve subjects crossed over to CBT-I after control treatment. Sleep and pain were assessed by self-report at baseline, after treatment, and (for CBT-I only) at 1-year follow-up.
Results: CBT-I subjects reported significantly improved sleep and significantly reduced pain after treatment. Control subjects reported no significant improvements. One-year follow-up found maintenance of improved sleep and reduced pain for both the CBT-I group alone and among subjects who crossed over from control to CBT-I.
Conclusions: CBT-I but not an attention control, without directly addressing pain control, improved both immediate and long-term self-reported sleep and pain in older patients with osteoarthritis and co-morbid insomnia. These results are unique in suggesting the long-term durability of CBT-I effects for co-morbid insomnia. They also indicate that improving sleep, per se, in patients with osteoarthritis may result in decreased pain. Techniques to improve sleep may be useful additions to pain management programs in osteoarthritis, and possibly other chronic pain conditions as well.
Keywords: CBT-I, sleep, pain, osteoarthritis, insomnia, co-morbid
What do abrupt changes in ocean circulation and Earth’s climate, shifts in wildlife populations and ecosystems, the global finance market and its system-wide crashes, and asthma attacks and epileptic seizures have in common?
According to a paper published this week in the journal Nature, all share generic early-warning signals that indicate a critical threshold of change dead ahead.
In the paper, Martin Scheffer of Wageningen University in The Netherlands and co-authors, including William Brock and Stephen Carpenter of the University of Wisconsin at Madison and George Sugihara of the Scripps Institution of Oceanography in La Jolla, Calif., found that similar symptoms occur in many systems as they approach a critical state of transition.
“It’s increasingly clear that many complex systems have critical thresholds — ‘tipping points’ — at which these systems shift abruptly from one state to another,” write the scientists in their paper.
Especially relevant, they discovered, is that “catastrophic bifurcations,” a diverging of the ways, propel a system toward a new state once a certain threshold is exceeded.
Like Robert Frost’s well-known poem about two paths diverging in a wood, a system follows a trail for so long, then often comes to a switchpoint at which it will strike out in a completely new direction.
That system may be as tiny as the alveoli in human lungs or as large as global climate.
“These are compelling insights into the transitions in human and natural systems,” says Henry Gholz, program director in the National Science Foundation (NSF)’s Division of Environmental Biology, which supported the research along with NSF’s Division of Ocean Sciences.
“The information comes at a critical time — a time when Earth’s and, our fragility, have been highlighted by global financial collapses, debates over health care reform, and concern about rapid change in climate and ecological systems.”
It all comes down to what scientists call “squealing,” or “variance amplification near critical points,” when a system moves back and forth between two states.
“A system may shift permanently to an altered state if an underlying slow change in conditions persists, moving it to a new situation,” says Carpenter.
Eutrophication in lakes, shifts in climate, and epileptic seizures all are preceded by squealing.
Squealing, for example, announced the impending abrupt end of Earth’s Younger Dryas cold period some 12,000 years ago, the scientists believe. The later part of this episode alternated between a cold mode and a warm mode. The Younger Dryas eventually ended in a sharp shift to the relatively warm and stable conditions of the Holocene epoch.
The increasing climate variability of recent times, state the paper’s authors, may be interpreted as a signal that the near-term future could bring a transition from glacial and interglacial oscillations to a new state — one with permanent Northern Hemisphere glaciation in Earth’s mid-latitudes.
In ecology, stable states separated by critical thresholds of change occur in ecosystems from rangelands to oceans, says Carpenter.
The way in which plants stop growing during a drought is an example. At a certain point, fields become deserts, and no amount of rain will bring vegetation back to life. Before this transition, plant life peters out, disappearing in patches until nothing but dry-as-bones land is left.
Early-warning signals are also found in exploited fish stocks. Harvesting leads to increased fluctuations in fish populations. Fish are eventually driven toward a transition to a cyclic or chaotic state.
Humans aren’t exempt from abrupt transitions. Epileptic seizures and asthma attacks are cases in point. Our lungs can show a pattern of bronchoconstriction that may be the prelude to dangerous respiratory failure, and which resembles the pattern of collapsing land vegetation during a drought.
Epileptic seizures happen when neighboring neural cells all start firing in synchrony. Minutes before a seizure, a certain variance occurs in the electrical signals recorded in an EEG.
Shifts in financial markets also have early warnings. Stock market events are heralded by increased trading volatility. Correlation among returns to stocks in a falling market and patterns in options prices may serve as early-warning indicators.
“In systems in which we can observe transitions repeatedly,” write the scientists, “such as lakes, ranges or fields, and such as human physiology, we may discover where the thresholds are.
“If we have reason to suspect the possibility of a critical transition, early-warning signals may be a significant step forward in judging whether the probability of an event is increasing.”
Nature 461, 53-59 (3 September 2009) | doi:10.1038/nature08227
Early-warning signals for critical transitions
Marten Scheffer, Jordi Bascompte, William A. Brock, Victor Brovkin5, Stephen R. Carpenter, Vasilis Dakos1, Hermann Held, Egbert H. van Nes, Max Rietkerk & George Sugihara
Abstract: Complex dynamical systems, ranging from ecosystems to financial markets and the climate, can have tipping points at which a sudden shift to a contrasting dynamical regime may occur. Although predicting such critical points before they are reached is extremely difficult, work in different scientific fields is now suggesting the existence of generic early-warning signals that may indicate for a wide class of systems if a critical threshold is approaching.