Sunday, December 23, 2007

Humor Develops From Aggression Caused By Male Hormones, Professor Says


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ScienceDaily (Dec. 23, 2007) — Humour appears to develop from aggression caused by male hormones, according to a study published in the Christmas issue of the British Medical Journal.

Professor Sam Shuster conducted a year long study observing how people reacted to him as he unicycled through the streets of Newcastle upon Tyne. What began as a hobby turned into an observational study after he realized that the huge number of stereotypical and predictable responses he received must be indicative of an underlying biological phenomenon.
The study was an observation of people's reactions to a sudden unexpected exposure to a new phenomenon - in this case unicycling, which at the time few had seen. He documented the responses of over 400 individuals, and observed the responses of many others.
Over 90% of people responded physically, for example with an exaggerated stare or a wave. Almost half responded verbally -- more men than women. Here, says Professor Shuster, the sex difference was striking. 95% of adult women were praising, encouraging or showed concern. There were very few comic or snide remarks. In contrast, only 25% of adult men responded as did the women, for example, by praise or encouragement; instead 75% attempted comedy, often snide or combative as an intended put-down.
Equally striking, he says, was the repetitive and predictable nature of the comments from men; two thirds of their 'comic' responses referred to the number of wheels - "Lost your wheel?", for example.
Professor Shuster also noticed the male response differed markedly with age, moving from curiosity in childhood (years 5-12) -- the same reaction as young girls, - to physical and verbal aggression in boys aged 11-13 who often tried to get him to fall off the unicycle.
Responses became more verbal during the later teens, turning into disparaging 'jokes' or mocking songs. This then evolved into adult male humour -- characterized by repetitive, humorous verbal put-downs concealing a latent aggression. Young men in cars were particularly aggressive. Professor Shuster notes that this is the age when men are at the peak of their virility. The 'jokes' were lost with age as older men responded more neutrally and amicably with few attempts at a jovial put-down.
The female response by contrast, was subdued during puberty and late teens -- normally either apparent indifference or minimal approval. It then evolved into the laudatory and concerned adult female response.
The idea that unicycling is intrinsically funny does not explain the findings, says Professor Shuster, particularly the repetitiveness, evolution and sex differences. Genetics may explain the sex difference but not the waxing and waning of the male response.
He says the simplest explanation for this change is the effect of male hormones such as testosterone, known collectively as androgens, which induce virility in men.
Particularly interesting for the evolution of humour is, he says, the observations that initial aggressive intent seems to become channeled into a verbal response which pushes it into a contrived, but more subtle and sophisticated joke, so the aggression is hidden by wit. The two then eventually split as the wit takes on an independent life of its own.
Adapted from materials provided by BMJ-British Medical Journal.

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Monkeys Can Perform Mental Addition


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ScienceDaily (Dec. 20, 2007) — Researchers at Duke University have demonstrated that monkeys have the ability to perform mental addition. In fact, monkeys performed about as well as college students given the same test.
The findings shed light on the shared evolutionary origins of arithmetic ability in humans and non-human animals, according to Assistant Professor Elizabeth Brannon, Ph.D. and Jessica Cantlon, Ph.D., of the Duke Center for Cognitive Neuroscience.
Current evidence has shown that both humans and animals have the ability to mentally represent and compare numbers. For instance, animals, infants and adults can discriminate between four objects and eight objects. However, until now it was unclear whether animals could perform mental arithmetic.
"We know that animals can recognize quantities, but there is less evidence for their ability to carry out explicit mathematical tasks, such as addition," said graduate student Jessica Cantlon. "Our study shows that they can."
Cantlon and Brannon set up an experiment in which macaque monkeys were placed in front of a computer touch screen displaying a variable number of dots. Those dots were then removed and a new screen appeared with a different number of dots. A third screen then appeared displaying two boxes; one containing the sum of the first two sets of dots and one containing a different number. The monkeys were rewarded for touching the box containing the correct sum of the sets.
The same test was presented to college students, who were asked to choose the correct sum without counting the individual dots. While the college students were correct 94 percent the time and the monkeys 76 percent, the average response time for both monkeys and humans was about one second.
Interestingly, both the monkeys' and the college students' performance worsened when the two choice boxes were close in number.
"If the correct sum was 11 and the box with the incorrect number held 12 dots, both monkeys and the college students took longer to answer and had more errors. We call this the ratio effect," explained Cantlon. "What's remarkable is that both species suffered from the ratio effect at virtually the same rate."
That monkeys and humans share the ability to add suggests that basic arithmetic may be part of our shared evolutionary past.
Humans have added language and writing to their repertoire, which undoubtedly changes the way we represent numbers. "Much of adult humans' mathematical capacity lies in their ability to represent numerical concepts using symbolic language. A monkey can't tell the difference between 2000 and 2001 objects, for instance. However, our work has shown that both humans and monkeys can mentally manipulate representations of number to generate approximate sums of individual objects," says Brannon.
Citation: Cantlon JF, Brannon EM (2007) Basic math in monkeys and college students. PLoS Biol 5(12): e328. doi:10.1371/journal.pbio.0050328
Adapted from materials provided by Duke University Medical Center.

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Wednesday, December 19, 2007

Does Time Slow In Crisis? No, Say Researchers


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ScienceDaily (Dec. 19, 2007) — In The Matrix, hero Neo wins his battles when time slows in the simulated world. In the real world, accident victims often report a similar slowing as they slide unavoidably into disaster. But can humans really experience events in slow motion?
Apparently not, said researchers at Baylor College of Medicine in Houston, who studied how volunteers experience time when they free-fall 100 feet into a net below. Even though participants remembered their own falls as having taken one-third longer than those of the other study participants, they were not able to see more events in time. Instead, the longer duration was a trick of their memory, not an actual slow-motion experience.
"People commonly report that time seemed to move in slow motion during a car accident," said Dr. David Eagleman, assistant professor of neuroscience and psychiatry and behavioral sciences at BCM. "Does the experience of slow motion really happen, or does it only seem to have happened in retrospect? The answer is critical for understanding how time is represented in the brain."
When roller coasters and other scary amusement park rides did not cause enough fear to make "time slow down," Eagleman and his graduate students Chess Stetson and Matthew Fiesta sought out something even more frightening. They hit upon Suspended Catch Air Device diving, a controlled free-fall system in which "divers" are dropped backwards off a platform 150 feet up and land safely in a net. Divers are not attached to ropes and reach 70 miles per hour during the three-second fall.
"It's the scariest thing I have ever done," said Eagleman. "I knew it was perfectly safe, and I also knew that it would be the perfect way to make people feel as though an event took much longer than it actually did."
The experiment consisted of two parts. In one, the researchers asked participants to reproduce with a stopwatch how long it took someone else to fall, and then how long their own fall seemed to have lasted. In general, people estimated that their own fall appeared 36 percent longer than that of their compatriots.
However, to determine whether that distortion meant they could actually see more events happening in time -- like a camera in slow motion -- Eagleman and his students developed a special device called the perceptual chronometer that was strapped to the volunteers' wrists. Numbers flickered on the screen of the watch-like unit. The scientists adjusted the speed at which the numbers flickered until it was too fast for the divers to see.
They theorized that if time perception really slowed, the flickering numbers would appear slow enough for the divers to easily read while in free-fall.
They found that while the subjects were able to read numbers presented at normal speeds during the free-fall, they could not read them at faster-than-normal speeds.
"We discovered that people are not like Neo in The Matrix, dodging bullets in slow-mo. The paradox is that it seemed to participants as though their fall took a long time. The answer to the paradox is that time estimation and memory are intertwined: the volunteers merely thought the fall took a longer time in retrospect," he said.
During a frightening event, a brain area called the amygdala becomes more active, laying down a secondary set of memories that go along with those normally taken care of by other parts of the brain.
"In this way, frightening events are associated with richer and denser memories. And the more memory you have of an event, the longer you believe it took," Eagleman explained.
The study allowed them to deduce that a person's perception of time is not a single phenomenon that speeds or slows. "Your brain is not like a video camera," said Eagleman.
Eagleman and his team have been able to verify this conclusion in the laboratory. In an experiment that appeared in a recent issue of PLoS One, Eagleman and graduate student Vani Pariyadath used 'oddballs' in a sequence to bring about a similar duration distortion. For example, when they flashed on the computer screen a shoe, a shoe, a shoe, a flower and a shoe, viewers believed the flower stayed on the screen longer, even though it remained there the same amount of time as the shoes.
Pariyadath and Eagleman showed that even though durations are distorted during the oddball, other aspects of time -- such as flickering lights or accompanying sounds -- do not change.
The conclusion from both studies was the same.
"It can seem as though an event has taken an unusually long time, but it doesn't mean your immediate experience of time actually expands. It simply means that when you look back on it, you believe it to have taken longer," Eagleman said.
"This is related to the phenomenon that time seems to speed up as you grow older. When you're a child, you lay down rich memories for all your experiences; when your older, you've seen it all before and lay down fewer memories. Therefore, when a child looks back at the end of a summer, it seems to have lasted forever; adults think it zoomed by."
The study appeared online recently in the journal Public Library of Science One. Funding for this research came from the National Institutes of Health.
Adapted from materials provided by Baylor College of Medicine.

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Wednesday, December 12, 2007

Parenting Practices Don't Suffer During Divorce, According To Large Study

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ScienceDaily (Dec. 12, 2007) — New research is challenging the notion that parents who divorce necessarily exhibit a diminished capacity to parent in the period following divorce. A large, longitudinal study conducted by University of Alberta sociology professor Lisa Strohschein has found that divorce does not change parenting behavior, and that there are actually more similarities than differences in parenting between recently divorced and married parents.
The study used data from the 1994 and 1996 cycles of the National Longitudinal Survey of Children and Youth (NSLCY) to compare changes in parenting practices between 208 households that divorced between the first and follow up interview and 4796 households that remained intact. Strohschein looked at three measures of parenting behavior (nurturing, consistent, and punitive parenting) to tap into the different ways that divorce is believed to disrupt parenting practices. Her results show that there are no differences between divorced and stably married parents for any parenting behavior either before or after a divorce has occurred.
"My findings that parenting practices are unrelated to divorce appear to fly in the face of accepted wisdom," states Strohschein. "Undoubtedly, some parents will be overwhelmed and unable to cope with the demands of parenting in the post-divorce period, but the expectation that all parents will be negatively affected by divorce is unfounded."
"This study is important because governments in both Canada and the US have allocated considerable resources over the past decade to provide parenting seminars on a mandatory or voluntary basis to parents who legally divorce," says Strohschein. "Although these programs do assist parents and children in adjusting to divorce, it is equally clear that not all parents will be well served by such programs. For those who work directly with families during the divorce process, this means making greater effort to build on the existing strengths of parents."
"Researchers need to shed much more light on the predictors of parenting behavior in the post-divorce period so that this knowledge can be used to design programs that effectively target the real needs of divorced parents," says Strohschein.
This study appears in Family Relations.
Adapted from materials provided by University of Alberta.

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www.oloscience.com

When She's Turned On, Some Of Her Genes Turn Off, Fish Study Shows

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ScienceDaily (Dec. 12, 2007) — When a female is attracted to a male, entire suites of genes in her brain turn on and off, show biologists from The University of Texas at Austin studying swordtail fish.
Molly Cummings and Hans Hofmann found that some genes were turned on when females found a male attractive, but a larger number of genes were turned off.
"When females were most excited--when attractive males were around--we observed the greatest down regulation [turning off] of genes," said Cummings, assistant professor of integrative biology. "It's possible that this could lead to a release of inhibition, a transition to being receptive to mating."
The same genes that turned on when the females were with attractive males turned off when they were with other females and vice versa.
This is one of few studies to link changes in the expression of genes with changes in an individual's behavior in different social situations.
Cummings and Hofmann suggest that the gene sets they studied could be involved in orchestrating mating responses in all vertebrates.
Their research appeared online December 4 in Proceedings of the Royal Society of London B.
Female swordtails are attracted to males that are large and have ornaments on their bodies, such as long tails and striking coloration.
In experiments, females were placed in the center of a tank separated into three zones for 30 minutes. When an attractive male was in one of the adjacent zones, females showed typical behaviors indicating that they had chosen the male for mating. The females were also tested with other females, with unattractive smaller males, and in empty tanks.
The researchers immediately extracted RNA from the females and used gene array technology to identify genes that were being up regulated (turned on) and down regulated (turned off) in the females' brains.
The researchers looked at more than 3,000 genes and found that 77 were involved in the females' mate choice behavior.
"We've found a number of new genes that haven't been implicated in mating behavior before," said Hofmann, assistant professor of integrative biology.
The genes turned on or off very quickly during the 30-minute testing period.
"What we have not appreciated until now is how dynamic the genome is," said Hofmann. "It is constantly changing and even in a very short period of time, 10 percent of the protein-coding genome can change its activity. We now have a genomic view of these dynamic processes within a social context."
The biologists next seek to identify specific regions in the brain where the genes are expressed. They also aim to enhance or inhibit specific genes and observe the resulting behavioral change.
"We'd like to take a female who is a 'high preference gal' and make her a 'low preference gal' and vice versa," said Cummings.
She said that gaining a better understanding of individual expression of behavior and its underlying genetic causes can shed light on how behavior drives and maintains the evolution and diversification of species.
Adapted from materials provided by University of Texas at Austin.

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Researchers Can Read Thoughts To Decipher What A Person Is Actually Seeing


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ScienceDaily (Dec. 11, 2007) — Following ground-breaking research showing that neurons in the human brain respond in an abstract manner to particular individuals or objects, University of Leicester researchers have now discovered that, from the firing of this type of neuron, they can tell what a person is actually seeing.
The original research by Dr R Quian Quiroga, of the University’s Department of Engineering, showed that one neuron fired to, for instance, Jennifer Aniston, another one to Halle Berry, another one to the Sydney Opera House, etc.
The responses were abstract. For example, the neuron firing to Halle Berry responded to several different pictures of her and even to the letters of her name, but not to other people or names.
This result, published in Nature in 2005 came from data from patients suffering from epilepsy. As candidates for epilepsy surgery, they are implanted with intracranial electrodes to determine as accurately as possible the area where the seizures originate. From that, clinicians can evaluate the potential outcome of curative surgery.
Dr Quian Quiroga’s latest research, which has appeared in the Journal of Neurophysiology, follows on from this.
Dr Quian Quiroga explained: “For example, if the 'Jennifer Aniston neuron' increases its firing then we can predict that the subject is seeing Jennifer Aniston. If the 'Halle Berry neuron' fires, then we can predict that the subject is seeing Halle Berry, and so on.
“To do this, we used and optimised a 'decoding algorithms', which is a mathematical method to infer the stimulus from the neuronal firing. We also needed to optimise our recording and data processing tools to record simultaneously from as many neurons as possible. Currently we are able to record simultaneously from up to 100 neurons in the human brain.
“In these experiments we presented a large database of pictures, and discovered that we can predict what picture the subject is seeing far above chance. So, in simple words, we can read the human thought from the neuronal activity.
“Once we reached this point, we then asked what are the most fundamental features of the neuronal firing that allowed us to make this predictions. This gave us the chance of studying basic principles of neural coding; i.e. how information is stored by neurons in the brain.
“For example, we found that there is a very limited time window in the neuronal firing that contains most of the information used for such predictions. Interestingly, neurons fired only 4 spikes in average during this time window. So, in another words, only 4 spikes of a few neurons are already telling us what the patient is seeing.”
Potential applications of this discovery include the development of Neural Prosthetic devices to be used by paralysed patients or amputees. A patient with a lesion in the spinal cord (as with the late Christopher Reeves), can still think about reaching a cup of tea with his arm, but this order is not transmitted to the muscles.
The idea of Neural Prostheses is to read these commands directly from the brain and transmit them to bionic devices such as a robotic arm that the patient could control directly from the brain.
Dr Quian Quiroga’s work showing that it is possible to read signals from the brain is a good step forward in this direction. But there are still clinical and ethical issues that have to be resolved before Neural Prosthetic devices can be applied in humans.
In particular, these would involve invasive surgery, which would have to be justified by a clear improvement for the patient before it could be undertaken.
Adapted from materials provided by University of Leicester.

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Monday, December 10, 2007

In Fruit Flies, Homosexuality Is Biological But Not Hard-wired, Study Shows


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ScienceDaily (Dec. 10, 2007) — While the biological basis for homosexuality remains a mystery, a team of neurobiologists reports they may have closed in on an answer -- by a nose.
The team led by University of Illinois at Chicago researcher David Featherstone has discovered that sexual orientation in fruit flies is controlled by a previously unknown regulator of synapse strength. Armed with this knowledge, the researchers found they were able to use either genetic manipulation or drugs to turn the flies' homosexual behavior on and off within hours.
Featherstone, associate professor of biological sciences at UIC, and his coworkers discovered a gene in fruit flies they called "genderblind," or GB. A mutation in GB turns flies bisexual.
Featherstone found the gene interesting initially because it has the unusual ability to transport the neurotransmitter glutamate out of glial cells -- cells that support and nourish nerve cells but do not fire like neurons do. Previous work from his laboratory showed that changing the amount of glutamate outside cells can change the strength of nerve cell junctions, or synapses, which play a key role in human and animal behavior.
But the GB gene became even more interesting when post-doctoral researcher Yael Grosjean noticed that all the GB mutant male flies were courting other males.
"It was very dramatic," said Featherstone. "The GB mutant males treated other males exactly the same way normal male flies would treat a female. They even attempted copulation."
Other genes that alter sexual orientation have been described, but most just control whether the brain develops as genetically male or female. It's still unknown why a male brain chooses to do male things and a female brain does female things. The discovery of GB provided an opportunity to understand why males choose to mate with females.
"Based on our previous work, we reasoned that GB mutants might show homosexual behavior because their glutamatergic synapses were altered in some way," said Featherstone. Specifically, the GB mutant synapses might be stronger.
"Homosexual courtship might be sort of an 'overreaction' to sexual stimuli," he explained.
To test this, he and his colleagues genetically altered synapse strength independent of GB, and also fed the flies drugs that can alter synapse strength. As predicted, they were able to turn fly homosexuality on and off -- and within hours.
"It was amazing. I never thought we'd be able to do that sort of thing, because sexual orientation is supposed to be hard-wired," he said. "This fundamentally changes how we think about this behavior."
Featherstone and his colleagues reasoned that adult fly brains have dual-track sensory circuits, one that triggers heterosexual behavior, the other homosexual. When GB suppresses glutamatergic synapses, the homosexual circuit is blocked.
Further work showed precisely how this happens -- without GB to suppress synapse strength, the flies no longer interpreted smells the same way.
"Pheromones are powerful sexual stimuli," Featherstone said. "As it turns out, the GB mutant flies were perceiving pheromones differently. Specifically, the GB mutant males were no longer recognizing male pheromones as a repulsive stimulus."
Featherstone says it may someday be possible to domesticate insects such as fruit flies and manipulate their sense of smell to turn them into useful pollinators rather than costly pests.
The research appeared on line December 10 in Nature Neuroscience, and is scheduled for print in the January issue.
Grosjean, now with the Center of Integrative Genomics in Lausanne, Switzerland, is the paper's first author. Along with Featherstone, authors include Hrvoje Augustin of UIC and Micheline Grillet and Jean-Francois Ferveur of the Université de Bourgogne in Dijon, France.
Adapted from materials provided by University of Illinois at Chicago.

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Sunday, December 9, 2007

Subliminal Smells Bias Perception About A Person's Likeability


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ScienceDaily (Dec. 8, 2007) — Anyone who has bonded with a puppy madly sniffing with affection gets an idea of how scents, most not apparent to humans, are critical to a dog's appreciation of her two-legged friends. Now new research from Northwestern University suggests that humans also pick up infinitesimal scents that affect whether or not we like somebody.
"We evaluate people every day and make judgments about who we like or don't like," said Wen Li, a post-doctoral fellow in the Cognitive Neurology and Alzheimer's Disease Center at Northwestern's Feinberg School of Medicine and lead author of the study. "We may think our judgments are based only on various conscious bits of information, but our senses also may provide subliminal perceptual information that affects our behavior."
Minute amounts of odors elicited salient psychological and physiological changes that suggest that humans get much more information from barely perceptible scents than previously realized.
To test whether subliminal odors alter social preferences, participants were asked to sniff bottles with three different scents: lemon (good), sweat (bad) and ethereal (neutral). The scents ranged from levels that could be consciously smelled to those that were barely perceptible. Study participants were informed that an odor would be present in 75 percent of the trials.
Most participants were not aware of the barely perceptible odors. After sniffing from each of the bottles, they were shown a face with a neutral expression and asked to evaluate it using one of six different rankings, ranging from extremely likeable to extremely unlikeable.
People who were slightly better than average at figuring out whether the minimal smell was present didn't seem to be biased by the subliminal scents.
"The study suggests that people conscious of the barely noticeable scents were able to discount that sensory information and just evaluate the faces," Li said. "It only was when smell sneaked in without being noticed that judgments about likeability were biased."
The conclusions fit with recent studies using visual stimuli that suggest that top-down control mechanisms in the brain can be exerted on unconscious processing even though individuals have no awareness of what is being controlled.
Besides Li, the study's co-investigators include Isabel Moallem, Loyola University; Ken Paller, professor of psychology in the Weinberg College of Arts and Sciences at Northwestern; and Jay Gottfried, assistant professor of neurology at Feinberg and senior author of the paper.*
"When sensory input is insufficient to provoke a conscious olfactory experience, subliminal processing prevails and biases perception," Paller said. "But as the awareness of a scent increases, greater executive control in the brain is engaged to counteract unconscious olfaction."
The acute sensitivity of human olfaction tends to be underappreciated. "In general, people tend to be dismissive of human olfaction and discount the role that smell plays in our everyday life," said Gottfried. "Our study offers direct evidence that human social behavior is under the influence of miniscule amounts of odor, at concentrations too low to be consciously perceived, indicating that the human sense of smell is much keener than commonly thought."
The study adds to a growing body of research suggesting that subliminal sensory information -- whether from scents, vision or hearing -- affects perception. "We are beginning to understand more about how perception and memory function," Paller said, "by taking into account various types of influences that operate without our explicit knowledge."
*The paper "Subliminal Smells Can Guide Social Preferences" was published in the December issue of Psychological Science.
Adapted from materials provided by Northwestern University.

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Friday, December 7, 2007

Humans Appear Hardwired To Learn By 'Over-Imitation'


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ScienceDaily (Dec. 6, 2007) — Children learn by imitating adults--so much so that they will rethink how an object works if they observe an adult taking unnecessary steps when using that object, according to a new Yale study.
"Even when you add time pressure, or warn the children not to do the unnecessary actions, they seem unable to avoid reproducing the adult's irrelevant actions," said Derek Lyons, doctoral candidate, developmental psychology, and first author of the study. "They have already incorporated the actions into their idea of how the object works."
Learning by imitation occurs from the simplest preverbal communication to the most complex adult expertise. It is the basis for much of our success as a species, but the benefits are less clear in instances of "over-imitation," where children copy behavior that is not needed, Lyons said.
It has been theorized that children over-imitate just to fit in, or out of habit. The Yale team found in this study that children follow the adults' steps faithfully to the point where they actually change their mind about how an object functions.
The study included three-to-five-year-old children who engaged in a series of exercises. In one exercise, the children could see a dinosaur toy through a clear plastic box. The researcher used a sequence of irrelevant and relevant actions to retrieve the toy, such as tapping the lid of the jar with a feather before unscrewing the lid.
The children then were asked which actions were silly and which were not. They were praised when they pinpointed the actions that had no value in retrieving the toy. The idea was to teach the children that the adult was unreliable and that they should ignore his unnecessary actions.
Later the children watched adults retrieve a toy turtle from a box using needless steps. When asked to do the task themselves, the children over-imitated, despite their prior training to ignore irrelevant actions by the adults.
"What of all of this means," Lyons said, "is that children's ability to imitate can actually lead to confusion when they see an adult doing something in a disorganized or inefficient way. Watching an adult doing something wrong can make it much harder for kids to do it right."
Journal reference: Proceedings of the National Academy of Sciences: online publication week of December 3, 2007 (doi/10.1073/pnas.0704452104)
Co-authors include Andrew Young of the University of Wisconsin-Madison and Frank Keil of Yale, who was the senior author.
Adapted from materials provided by Yale University.

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