Anthropology News, Science News

Mice carrying a “humanized version” of a gene believed to influence speech and language may not actually talk, but they nonetheless do have a lot to say about our evolutionary past, according to a report in the May 29th issue of the journal Cell, a Cell Press publication.

“In the last decade or so, we’ve come to realize that the mouse is really similar to humans,” said Wolfgang Enard of the Max-Planck Institute for Evolutionary Anthropology. “The genes are essentially the same and they also work similarly.” Because of that, scientists have learned a tremendous amount about the biology of human diseases by studying mice.

“With this study, we get the first glimpse that mice can be used to study not only disease, but also our own history.”

Enard said his team is generally interested in the genomic differences that set humans apart from their primate relatives. One important difference between humans and chimpanzees they have studied are two amino acid substitutions in FOXP2. Those changes became fixed after the human lineage split from chimpanzees and earlier studies have yielded evidence that the gene underwent positive selection. That evolutionary change is thought to reflect selection for some important aspects of speech and language.

“Changes in FOXP2 occurred over the course of human evolution and are the best candidates for genetic changes that might explain why we can speak,” Enard said. “The challenge is to study it functionally.”

For obvious reasons, the genetic studies needed to sort that out can’t be completed in humans or chimpanzees, he said. In the new study, the researchers introduced those substitutions into the FOXP2 gene of mice. They note that the mouse version of the gene is essentially identical to that of chimps, making it a reasonable model for the ancestral human version.

Mice with the human FOXP2 show changes in brain circuits that have previously been linked to human speech, the new research shows. Intriguingly enough, the genetically altered mouse pups also have qualitative differences in ultrasonic vocalizations they use when placed outside the comfort of their mothers’ nests. But, Enard says, not enough is known about mouse communication to read too much yet into what exactly those changes might mean.

Although FoxP2 is active in many other tissues of the body, the altered version did not appear to have other effects on the mice, which appeared to be generally healthy.

Those differences offer a window into the evolution of speech and language capacity in the human brain. They said it will now be important to further explore the mechanistic basis of the gene’s effects and their possible relationship to characteristics that differ between humans and apes.

“Currently, one can only speculate about the role these effects may have played during human evolution,” they wrote. “However, since patients that carry one nonfunctional FOXP2 allele show impairments in the timing and sequencing of orofacial movements, one possibility is that the amino acid substitutions in FOXP2 contributed to an increased fine-tuning of motor control necessary for articulation, i.e., the unique human capacity to learn and coordinate the muscle movements in lungs, larynx, tongue and lips that are necessary for speech. We are confident that concerted studies of mice, humans and other primates will eventually clarify if this is the case.”

First study to look at effect of greenness on inner city children's weight over time

San Diego, October 28, 2008 – Childhood obesity can lead to type 2 diabetes, asthma, hypertension, sleep apnea and emotional distress. Obese children and youth are likely to be obese as adults, experience more cardiovascular disease, high blood pressure and stroke and incur higher healthcare costs. In an article published in the December 2008 issue of the American Journal of Preventive Medicine, researchers report that children living in inner city neighborhoods with higher "greenness" experienced lower weight gains compared to those in areas with less green space.

Researchers from the University of Washington, Indiana University-Purdue University and Indiana University School of Medicine followed more than 3800 children, predominantly African-American and poor, aged 3-16 over a two-year period. Using satellite imaging data to measure vegetation coverage, the investigators found that higher greenness was significantly associated with lower body mass index (BMI) changes in those children. In previous studies of adults, residential density tended to predict physical activity levels, with highly urban environments leading to more walking, less driving and lower BMI. The current study did not find this correlation for children.

Children and youth in urban environments may be active in a wider variety of open spaces (e.g., yards, parks, vacant lots) and less likely to constrain activity to streets and sidewalks. Greenness might indicate proximity to parks, playfields or other open spaces that promote either physical activity or increased time spent outdoors in active play.

Writing in the article, Janice F. Bell, PhD, MPH, Assistant Professor in the department of Health Services at the School of Public Health and Community Medicine, University of Washington, Seattle, and co-investigators state, "This study's findings align with previous research linking exposure to green landscapes with health improvements. Among adults, greenness is associated with less stress and lower BMI, improved self-reported health and shorter post-operative recovery periods. Among children and youth, the positive health effects of green landscapes include improved cognitive functioning and reduced attention deficit hyperactivity disorder symptoms. Ideally, future research in this area will be multidisciplinary – involving city planners, architects, geographers, psychologists and public health researchers – and will consider the ways children live and play in urban environments."

In a commentary published in the same issue of the American Journal of Preventive Medicine, Nick Wareham, MBBS, PhD, of the Institute of Metabolic Science, Cambridge, England, writes, "Previous research on factors associated with physical activity in children has used mostly cross-sectional designs and few prospective studies have been published. In addition, studies have focused mostly on individual biological or psychological factors, with little emphasis, until recently, on collective determinants such as the physical environment. By focusing on environmental determinants in a longitudinal study in children, the study by Bell et al makes an important contribution to the existing literature."

http://www.eurekalert.org/pub_releases/2008-10/ehs-gnm102608.php

Carriers of a common gene variation startled more dramatically in response to unpleasant pictures

Inborn differences may help explain why trauma gives some people bad
memories and others the nightmare of post-traumatic stress. Scientists
in Germany and the United States have reported evidence linking genes
to anxious behavior. The findings appear in the August issue of
Behavioral Neuroscience, published by the American Psychological
Association.

By showing that people who carry a common
variation of a gene that regulates the neurotransmitter dopamine have
an exaggerated "startle" reflex when viewing unpleasant pictures, the
researchers offer a biochemical explanation for why some people find it
harder to regulate emotional arousal. Their sensitivity may, in
combination with other hereditary and environmental factors, make them
more prone to anxiety disorders.

Researchers including
Martin Reuter, PhD, of the University of Bonn, Germany, recruited 96
women averaging 22 years old from the Giessen Gene Brain Behavior
Project, which investigates biomolecular causes of individual
differences in behavior.

The researchers first determined
which participants carried which variations (alleles) of the COMT gene,
which encodes an enzyme that breaks down dopamine, weakening its
signal. (COMT stands for a catabolic enzyme named
catechol-O-methyltransferase.) Scientists call its two alleles Val158
and Met158. Depending on ethnicity, more or less half the population
carries one copy of each. The rest of the population is roughly divided
between carrying two copies of Val158 and two copies of Met158.

Using
a well-validated psychophysiological measure, the researchers next
measured the intensity of each participant’s startle response by
attaching electrodes to the eye muscles that, upon emotional arousal,
contract and cause a blink. Participants then viewed pictures that were
emotionally pleasant (such as animals or babies), neutral (such as a
power outlet or hairdryer), or aversive (such as weapons or injured
victims at a crime scene) — 12 pictures of each type for six seconds
each. A loud, 35-millisecond white noise, called a startle probe,
sounded at random while they watched. When participants blinked,
showing the startle response, a bioamplifier took readings from the
electrodes and sent the information to a computer for analysis.

People
carrying two copies of the Met158 allele of the COMT gene showed a
significantly stronger startle reflex in the unpleasant-picture
condition than did carriers of either two copies of Val158 allele or
one copy of each. The two-Met carriers also disclosed greater anxiety
on a standard personality test.

This finding confirms that
specific variations in the gene that regulates dopamine signaling may
play a role in negative emotionality. The authors speculated that the
Met158 allele may raise levels of circulating dopamine in the brain’s
limbic system, a set of structures that support (among other things)
memory, emotional arousal and attention. The researchers said that more
dopamine in the prefrontal cortex could result in an "inflexible
attentional focus" on unpleasant stimuli, meaning that Met158 carriers
can’t tear themselves away from something that’s arousing — even if
it’s bad.

The Met158 allele was created by a relatively
recent mutation and only in the evolution of human beings. Other
primate species such as chimpanzees carry only the Val/Val genotype.
Co-author Christian Montag, Dipl. Psych., observes that for humans,
wariness may have been adaptive. He points out, "It was an advantage to
be more anxious in a dangerous environment."

A single gene
variation, says Montag, can explain only a small portion of variation
in anxious behavior – otherwise, in theory, up to half the population
could be anxious.

"This single gene variation is potentially
only one of many factors influencing such a complex trait as anxiety,"
he says. "Still, to identify the first candidates for genes associated
with an anxiety-prone personality is a step in the right direction."

Although
a great deal more research is needed, Montag says that if this line of
research bears fruit, one day "it might be possible to prescribe the
right dose of the right drug, relative to genetic makeup, to treat
anxiety disorders."

Source American Psychological Association

Less able to achieve their life goals, women end up unhappier than
men later in life – even though they start out happier, reveals new
research by Anke Plagnol of the University of Cambridge, and University
of Southern California economist Richard Easterlin.

Plagnol and Easterlin’s study, forthcoming in the Journal of Happiness Studies,
is the first to use nationally representative data spanning several
decades to examine the role of unfulfilled desires in a person’s sense
of well-being.

As the researchers explain, expectations of
success may vary among those raised in different generations (i.e., an
economic depression). Data sets from a range of time periods may also
have different demographic compositions.

In their analysis,
the researchers control for birth cohort and demographic
characteristics such as race and education. They find that women are,
on average, happier than men in early adulthood – but the glow wears
off with time. Specifically, after the age of 48, men’s overall
happiness exceeds women’s happiness.

These gender patterns of
overall happiness correlate to patterns in two significant aspects of
life satisfaction: family and finances.

As Plagnol explains:
In later life it is "men [who] come closer to fulfilling their
aspirations, are more satisfied with their family lives and financial
situations, and are the happier of the two."

Women and men
have fairly similar life goals when it comes to love, the study
reveals. Nine out of 10 people of both genders reach adult life wanting
a happy marriage.

"Differences between men and women in
aspirations for marriage and children are fairly small," says Plagnol,
who received her Ph.D. from USC in 2007. "Gender differences in
satisfaction depend largely on attainment."

The saddest period of the average man’s life – his 20s – is also the period when he is most likely to be single.

Young
men are also more dissatisfied than young women with their financial
situations, not because they are worse off, but because they want more
and therefore experience a greater "shortfall," the researchers explain.

But age alters many things, including men’s money woes and lackluster love lives.

After
34, men are more likely to be married than women, and the gap only
widens with age, mirroring men’s growing satisfaction with family life.

Men
also become more satisfied with their financial situations over time,
as reflected in their increased spending power. The researchers found
that men tend to covet big-ticket items that might not be within reach
until later in life, such as a car or vacation home.

(A notable exception: women want more "nice clothes" than men, the researchers found.)

These
findings are consistent with an earlier study by Easterlin showing that
recent generations are less satisfied than previous generations,
despite having more.

"Of course, one doesn’t have to be
married to be happy, but if that’s something you really want – and it
is for most people – then the failure to attain it can have an impact
on your overall happiness," Plagnol says, adding that those in a
relationship also tend to be in a stronger financial position than
those who must depend solely on their own resources.

Some age milestones:

41: Age at which men’s financial satisfaction exceeds women’s financial satisfaction

48: Age at which men’s overall happiness exceeds women’s overall happiness

64: Age at which men’s satisfaction with family life exceeds women’s satisfaction

With thanks to the University of Southern California

A new analysis of a 2005 survey of American schoolchildren has
identified factors that may be used to help improve school safety. The
research, published in BioMed Central’s open access journal Annals of General Psychiatry, gives detailed information about the carrying of guns, blades and clubs.

13,707
students participated in the study, 6,664 (50.5%) were male and 7,193
(49.5%) were females. Overall, 10.2% of males and 2.6% of females
reported carrying a weapon on school property. An estimated 29.8% of
males and 19.3% of females had carried weapons elsewhere.

The
analysis was carried out by Emmanuel Rudatsikira, from the Loma Linda
University, California, and his colleagues. They showed that the
variables most associated with the carrying of weapons were being male
and being a member of certain self-selected racial groups. Pupils who
identified themselves as white were more likely to carry weapons than
those who identified themselves as black.

The authors point
out that, "We do not believe that there are any inherent genetic
differences that determine race and that affect the way that
adolescents behave. We take the view that racial categorization has
facilitated the distribution of social and economic resources (housing,
school districts, wealth, social networks) that may consequently
influence adolescent behaviors and perceptions toward violent
behavior".

The results were surprising. The authors state that as the poor are
likely to live in violent neighbourhoods, they would be more likely to
feel unsafe and therefore carry weapons to school, "We would have
expected that minorities such as African Americans, being largely
disadvantaged in the United States, would be more likely to bear
weapons." Rudatsikira suggests some explanations for this apparent
discrepancy "If black students felt less threatened at school, it’s
less likely they’ll carry weapons. Alternatively, the schools they
attend may be more vigilant in policing weapon carrying as a possible
result of high violence and weapon bearing in black neighbourhoods."

Other
factors associated with weapon carrying were substance use, depression,
having been a victim of theft or property damage at school, having been
raped, having been threatened with a weapon or having been involved in
a physical fight.

Adolescent girls who had a serious school failure by the 12th grade
– being expelled, suspended or dropping out – were significantly more
likely to have suffered a serious bout of depression at the age of 21
than girls who did not have these problems.

New research published this week in the Journal of Adolescent Health
showed that girls who had early conduct problems in elementary school
also were at increased risk for depression in early adulthood. However,
the University of Washington study did not show any link for boys
between academic, behavior or social problems and depression at age 21.

"For
girls there are broader implications of school failure," said Carolyn
McCarty, a UW research associate professor of pediatrics and lead
author of the study. "We already know that it leads to more poverty,
higher rates of being on public assistance and lower rates of job
stability. And now this study shows it is having mental health
implications for girls."

The study showed that girls who were
expelled from school were more than twice as likely to suffer
depression – 44 percent compared to 20 percent of girls who were not
expelled. Thirty-three percent of the girls who dropped out of school
later became depressed compared to 19 percent who were not dropouts.
Twenty-eight percent of the girls who were suspended later suffered
depression versus 19 percent of girls who weren’t suspended.

Overall,
45 percent of the girls and 68 percent of the boys in the study
experienced a major school failure, but McCarty said these rates were
not surprising since the participants in the study came from high-crime
neighborhoods. However, the depression rate was higher among girls, 22
percent versus 17 percent for the boys.

"This gender paradox shows that while school failure is more
atypical for girls it appears to have more severe consequences when it
does occur," said McCarty. "One reason may be that school failure
stigmatizes girls more strongly or is harder for them to overcome. We
do know that girls with conduct problems, such as school failure, tend
to have long-term problems with cascading effects."

She said
the study’s overall gender rates of depression are comparable to
previous studies, although the 17 percent rate for boys was somewhat
high.

Data for the study was drawn from the UW’s ongoing
Seattle Social Development Research Project that was launched in 1985
and has been tracking 808 people since they were in the fifth grade.
Students were drawn from 18 Seattle schools in high-crime neighborhoods
to study the development of positive and antisocial behaviors.
Participants were almost equally divided by gender and identified
themselves as white (46 percent), black (24 percent), Asian-American
(21 percent), Native American (6 percent) and other groups (3 percent).

McCarty
said the study points to the need for communities to create integrated
prevention programs to help children deal with academic, social and
behavioral problems.

"When adolescents have these kinds of
problems and experiences, the response tends to be focused purely on
the academic, in part because the school and mental health systems are
distinct. We need to look more broadly at functioning and see what is
going on with other aspects of their lives including the psychological.
We can’t just put a Band-Aid on one thing that seems to be a problem
because often there is an underlying bigger issue that has to be
addressed," she said.

"When school failure emerges we should
have remedies and be ready to intervene at that point to prevent later
depression" said McCarty, who is directing a middle school study that
is evaluating early prevention efforts to thwart depression. "Social
and emotional skills are vital to adolescents and they may or may not
be taught by schools and their parents. We need to have school-based
prevention programs available before problems get much bigger and
harder to resolve."

MBL Visiting Investigators Explore the Evolution of Social Communication

MBL, WOODS HOLE, MA—A male midshipman, a close relative of the
toadfish, doesn’t need good looks to attract a mate – just a nice
voice. After building a nest for his potential partner, he calls to
nearby females by contracting his swim bladder, the air-filled sac fish
use to maintain buoyancy. The sound he makes is not a song or a
whistle, but a hum; more reminiscent of a long-winded foghorn than a
ballad. Female midshipman find it very alluring, and they only approach
a male’s nest if he makes this call.

In a paper published this week in Science,
three Marine Biological Laboratory (MBL) visiting investigators show
that the sophisticated neural circuitry that midshipman use to vocalize
develops in a similar region of the central nervous system as the
circuitry that allows a human to laugh or a frog to croak, evidence
that the ability to make and respond to sound is an ancient part of the
vertebrate success story. The research is presented by Andrew Bass of
Cornell University, Edwin Gilland of Howard University College of
Medicine, and Robert Baker of New York University Medical Center.

“Fish have all the same parts of the brain that you do,” says Bass, the
paper’s lead author. The way our brains work is also similar. Just as
we have neurons that coordinate when our larynx and tongue change shape
to produce words, toadfish and midshipman orchestrate the movement of
muscles attached to their swim bladder to produce grunts and hums.

Using larval toadfish and midshipman, the group traced the development
of the connection from the animal’s vocal muscles to a cluster of
neurons located in a compartment between the back of its brain and the
front of its spinal cord. The same part of the brain in more complex
vertebrates, such as humans, has a similar function, indicating that it
was highly selected for during the course of evolution.

Scientists have known for decades that these fish make sounds, but they
are not the only species whose hums, growls, and grunts have meaning.
“There’s reason to suggest that the use of sound in social
communication is widespread among fishes,” Bass says.

This research is an example of the growing field of evolutionary
neurobiology, which aims to understand the evolution of behavior
through neurobiology. According to Bass, fish are an incredibly
successful group, making up nearly half of the living species of
vertebrates, and vocal communication may be partly responsible. “The
kind of work we’re doing contributes to answering questions as to why
these animals are so successful,” Bass says. “We’re only touching the
tip of the iceberg here.”

The majority of this research was completed at the MBL over the past
five years, although the question of how fish communicate through sound
first came to Bass as a graduate student studying the neurobiology of
fish at the University of Michigan. In the summer of 1986, Bass, then a
summer instructor at the MBL, met Robert Baker, who was also
researching the neurobiology of fish calling. For years they discussed
fish social behavior with the roots of the hypothesis tested in the Science
paper first published in 1997 and the research to test that hypothesis
beginning in 2003. “The whole project began at the MBL,” Bass says.
“It’s where collaborations happen.”

Source

Researchers at Yale School of Medicine have found signs of an
apparent connection between bullying, being bullied and suicide in
children, according to a new review of studies from 13 countries
published in the International Journal of Adolescent Medicine and Health.

"While
there is no definitive evidence that bullying makes kids more likely to
kill themselves, now that we see there’s a likely association, we can
act on it and try to prevent it," said review lead author Young-Shin
Kim, M.D., assistant professor at Yale School of Medicine’s Child Study
Center.

In the review, Kim and colleague Bennett Leventhal,
M.D., analyzed 37 studies that examined bullying and suicide among
children and adolescents. The studies took place in the United States,
Canada, several European countries (including the United Kingdom and
Germany), South Korea, Japan and South Africa.

Almost all of
the studies found connections between being bullied and suicidal
thoughts among children. Five reported that bullying victims were two
to nine times more likely to report suicidal thoughts than other
children were.

Not just the victims were in danger: "The
perpetrators who are the bullies also have an increased risk for
suicidal behaviors," Kim said.

However, the way the studies
were designed made it impossible for researchers to determine
conclusively whether bullying leads to suicide, Kim said. In addition,
the authors report that most of the studies failed to take into account
the influence of factors like gender, psychiatric problems and a
history of suicide attempts.

Kim said her interest in
bullying grew several years ago when she visited South Korea and heard
several new slang terms referring to bullies and their victims. The
words reflected "an elaborated system of bullying," she said.

According
to international studies, bullying is common and affects anywhere from
9 percent to 54 percent of children. In the United States, many have
blamed bullying for spurring acts of violence, including the Columbine
High School massacre.

In the United States, many adults scoff
at bullying and say, "Oh, that’s what happens when kids are growing
up," according to Kim, who argues that bullying is serious and causes
major problems for children.

Kim is currently studying whether
being bullied actually leads to suicide, although she acknowledges it
will be difficult for researchers to get a firm grasp on a
cause-and-effect relationship. She said that to confirm a definitive
link, researchers would have to rule out the possibility that some
unknown factor makes certain children more susceptible to both bullying
and suicide.

For now, Kim said, the existing research should
encourage adults to pay more attention to bullying and signs of
suicidal behavior in children. "When we see kids who are targets of
bullying, we should ask them if they’re thinking about hurting
themselves," she said. "We should evaluate and prevent these things
from happening."

With thanks to Yale University

People in most countries around the world are happier these days,
according to newly released data from the World Values Survey based at
the University of Michigan Institute for Social Research.

Data
from representative national surveys conducted from 1981 to 2007 show
the happiness index rose in an overwhelming majority of nations
studied.

"It’s a surprising finding," said U-M political
scientist Ronald Inglehart, who directs the World Values Surveys and is
the lead author of an article on the topic to be published in the July
2008 issue of the journal Perspectives on Psychological Science. "It’s widely believed that it’s almost impossible to raise an entire country’s happiness level."

The
2007 wave of the surveys also provides a ranking of 97 nations
containing 90 percent of the world’s population. The results indicate
that Denmark is the happiest nation in the world and Zimbabwe the
unhappiest. The United States ranks 16th on the list, immediately after
New Zealand.

During the past 26 years, the World Values
Surveys have asked more than 350,000 people how happy they are, using
the same two questions.

"Taking all things together, would you
say you are very happy, rather happy, not very happy, not at all
happy?" And, "All things considered, how satisfied are you with your
life as a whole these days?"

Combining responses to these
two questions, Inglehart and colleagues constructed an index of
subjective well-being that reflects both happiness and general life
satisfaction.

In the 52 countries for which a substantial
time series is available (covering 17 years on average), this index
rose in 40 countries and fell in only 12. The average percentage of
people who said they were "very happy" increased by almost seven points.

"Most
earlier research has suggested that happiness levels are stable,"
Inglehart said. "Important events like winning the lottery or learning
you have cancer can lead to short-term changes, but in the long run
most previous research suggests that people and nations are stuck on a
‘hedonic treadmill.’ The belief has been that no matter what happens or
what we do, basic happiness levels are stable and don’t really change."

The
new findings from the World Values Surveys not only show that during
the past 25 years, happiness has in fact risen substantially in most
countries. Fully as important as the fact that happiness rose is the
reason why. In recent decades, low-income countries such as India and
China have experienced unprecedented rates of economic growth, dozens
of medium-income countries have democratized and there has been a sharp
rise of gender equality and tolerance of ethnic minorities and gays and
lesbians in developed societies.

Economic growth,
democratization and rising social tolerance have all contributed to
rising happiness, with democratization and rising tolerance having even
more impact than economic growth. All of these changes have contributed
to providing people with a wider range of choice in how to live their
lives—which is a key factor in happiness.

The people of rich
countries tend to be happier than those of poor countries, but even
controlling for economic factors, certain types of societies are much
happier than others.

"The results clearly show that the
happiest societies are those that allow people the freedom to choose
how to live their lives," Inglehart said.

As an example,
Inglehart points to the tolerant social norms and democratic political
systems in Denmark, Iceland, Switzerland, the Netherlands and Canada
all of which rank among the 10 happiest countries in the world.

"The
events of the past 25 years have brought a growing sense of freedom
that seems to be even more important than economic development in
contributing to rising happiness," Inglehart said. "Moreover, the most
effective way to maximize happiness seems to change with rising levels
of economic development. In subsistence-level societies, happiness is
closely linked with in-group solidarity, religiosity and national
pride. At higher levels of economic security, free choice has the
largest impact on happiness."

He also notes that the largest
recent increases on the subjective well-being index, measuring both
happiness and life-satisfaction, occurred in the Ukraine, followed by
Moldova, Slovenia, Nigeria, Turkey and Russia.

"While most
ex-communist countries show low levels of happiness, many of them show
large recent increases in subjective well-being," Inglehart said. "The
collapse of communism was generally followed by a sharp decline in
well-being, which tended to rise again with economic recovery."

Useful Links

For more information on the World Values Survey: www.worldvaluessurvey.org
Happiness Trends

Bicultural people may unconsciously change their personality when they switch languages, according to a US study on bilingual Hispanic women.

It found that women who were actively involved in both English and Spanish speaking cultures interpreted the same events differently, depending on which language they were using at the time.

It is known that people in general can switch between different ways of interpreting events and feelings – a phenomenon known as frame shifting. But the researchers say their work shows that bilingual people that are active in two different cultures do it more readily, and that language is the trigger.

Onepart of the study got the volunteers to watch TV advertisements showingwomen in different scenarios. The participants initially saw the ads in one language – English or Spanish – and then six months later in the other.

Researchers David Luna from Baruch College, New York, US, and Torsten Ringberg and Laura Peracchio from the University of Wisconsin-Milwaukee US, found that women classified themselves and others as more assertive when they spoke Spanish than when they spoke English.

"In the Spanish-language sessions, informants perceived females as more self-sufficient and extroverted," they say.

For example, one person saw the main character in the Spanish version of a commercial as a risk-taking, independent woman, but as hopeless, lonely, and confused in the English version.