Sounds like the auditory cortex has a dual pathway tooFor some time now we've known that in the brains of humans, monkeys and cats, visual information is processed by two separate streams - one for working out where things are and the other for processing what they are. Now Stephen Lomber and Shveta Malhotra have conducted an experiment on cats and provided perhaps the strongest evidence to date that, in the mammalian brain, sounds too are processed via two separate "what" and "where" streams.Lomber and Malhotra used a new cooling method to reversibly knock-out specific areas of the cats' auditory cortex - the part of the brain used for processing sound. The new technique involves surgically implanting small tubes into the cat's brain, through which chilled menthol is passed. In mammals, communication between brain cells stops when temperatures drop below 20 degrees Celsius, so cooling of the implanted tubes can be used to inhibit activity in a chosen localised brain region.Tests on three cats showed that cooling of the more frontal part of their auditory cortex impaired their ability to localise sounds (the "where" function), but didn't affect their ability to discriminate between sounds (the "what function"). By contrast, cooling of a rear part of the auditory cortex had the opposite effect: it impaired the cats' ability to discriminate sounds, but didn't affect their sound localisation skills.This pattern of results is known as a double dissociation and is the gold standard test in classic cognitive neuropsychology for demonstrating that two separate brain regions are responsible for independent functions. Before now, the evidence for "what" and "where" pathways in the auditory cortex was far weaker, having been based largely on recordings of single cell activity in monkeys or brain imaging in humans.In a commentary on this new research, Christian Sumner and colleagues agree that this is strong evidence, but they caution that the complete picture may turn out to be more complicated. "'What' and 'where' are appealing concepts," they wrote, "but it seems probable that cortical processing is more refined and more plastic."_________________________________Lomber, S.G., Malhotra, S. (2008). Double dissociation of 'what' and 'where'processing in auditory cortex. Nature Neuroscience, 11(5), 609-616.Author weblink:
sábado, julio 31, 2010
The unsung pioneers in the study of prejudice
When did the scholarly study of prejudice begin? Most people cite Gordon Allport's seminal work 'The Nature of Prejudice' published in 1954, but according to Russell Webster and colleagues the first scholar to propose a working definition of prejudice was actually the English humanist and literary critic William Hazlitt, writing way back in 1830.Inspired in part by his visit to France where he discovered the French were not as 'butterfly, airy, thoughtless, fluttering' as conventional stereotypes of the time predicted, Hazlitt proposed that 'prejudice ... is prejudging any question without having sufficiently examined it, and adhering to our opinion upon it through ignorance, malice, or perversity, in spite of every evidence to the contrary' - a definition that accurately anticipated Allport's own definition and research more than a century later. Ironically, Hazlitt revealed his own sexist prejudices in his writing, claiming that women are 'naturally physiognomists, and men phrenologists', by which he meant that women judge by sensations, men by rules.The first psychologist to define prejudice and urge psychologists to study it, according to Webster and co, was Josiah Morse (born Moses), a student of G Stanley Hall's at Clark University. Morse, a Jew, changed his name after struggling to gain postgraduate employment (as an aside, Harry Harlow, born Israel, is another Jewish psychologist who changed his name to boost his employment prospects). Morse encountered these difficulties despite Hall writing a letter of recommendation, shocking by today's standards, in which he stated that Morse 'has none of the objectional Jewish traits ... and has no Jewish features'. No doubt inspired by his first-hand experience of prejudice, Morse in 1907 wrote a paper in which he drew attention to the ubiquity of prejudice and, with echoes of Hazlitt, defined it as 'when one fails to adjust or correct one's prejudgement in favour of contrary evidence.'Another early psychologist to write on prejudice was G.T.W. Patrick, also a student of G. Stanley Hall. In 1890 Patrick published a paper in which he defined prejudice as 'individual deviation from the normal beliefs of mankind, taking as standard the universal, the general, or the mean'. Unlike Hazlitt and Morse, he failed to recognise that a key aspect of prejudice is the inability or reluctance to modify judgements in the face of fresh evidence. But like Hazlitt, Patrick betrayed his own sexist prejudices, writing that the 'woman's mind is less adapted than the man's', although to be fair he did concede that this is only 'an indication' and 'not proved'.What's remarkable about the writings of Hazlitt, Patrick and Morse is their prescience. For example, they recognised the influence of both explicit and non-conscious, implicit beliefs, and they realised that prejudice has some adaptive value in helping strengthen in-group bonds. Writing in 1904, William Thomas, a sociologist and the last scholar mentioned by Webster and colleagues, even anticipated Allport's Contact Hypothesis - the idea that inter-group prejudice can be reduced by members of distinct groups socialising with each other.'...These early pioneers deserve explicit credit for recognising prejudice as a phenomenon and one in dire need of psychological study,' Webster and colleagues conclude. 'Contemporary psychologists and sociologists who study stereotyping, prejudice, and discrimination will hopefully have a renewed appreciation for these individuals who planted the roots of prejudice research in psychology and sociology.'_________________________________Webster RJ, Saucier DA, & Harris RJ (2010). Before the measurement of prejudice: Early psychological and sociological papers on prejudice. Journal of the history of the behavioral sciences, 46 (3), 300-313http://www.ncbi.nlm.nih.gov/pubmed/20623744Author weblink: http://www.k-state.edu/psych/research/harris_richard.htm
domingo, julio 25, 2010
We are better at spotting fake smiles when feeling rejected
The last thing you need if you're feeling rejected is to waste time pursuing
friendships with people who aren't genuinely interested. That's according to
Michael Bernstein and his colleagues, who say we've actually evolved a
perceptual adaptation to rejection that helps prevent this from happening.
Bernstein's team provoked feelings of rejection in students by asking them
to write about a time they felt rejected or excluded. These students were
subsequently better at distinguishing fake from real smiles as depicted in
four-second video clips, than were students who'd either been asked to write
about a time they felt included, or to write about the previous morning.
"These results are among the first to show that rejection can lead to
increases in performance at the perceptual level, provided that the
performance supports opportunities for affiliation," the researchers said.
However, I wonder if this increased ability to detect fake smiles is as
adaptive as the researchers imply. In the same way that unrealistically
positive beliefs about the self can guard against depression, perhaps it
would be more helpful to a socially excluded person to tone down their
sensitivity to fake smiles. After all, just because a stranger gives you a
fake smile doesn't mean they aren't a potential friend - they may just have
had a bad day.
Michael J. Bernstein, Steven G. Young, Christina M. Brown, Donald F. Sacco,
Heather M. Claypool (2008). Adaptive Responses to Social Exclusion: Social
Rejection Improves Detection of Real and Fake Smiles. Psychological Science,
19 (10), 981-983.http://dx.doi.org/10.1111/j.1467-9280.2008.02187.x
sábado, julio 24, 2010
Your personality could affect the age you live to
People with more conscientious personalities, who have greater ambition and discipline, live longer. That's according to Margaret Kern and Howard Friedman who combined data on this topic from over 20 previous studies, involving more than 8,900 participants in the United States, Canada, Germany, Norway, Japan and Sweden - many of whom had illnesses like heart disease or cancer.
On average, people who scored higher on measures of conscientiousness (agreeing, for example, with statements like "I plan ahead" and disagreeing with statements like "My house is a mess") tended to live between two and four years longer than low scorers.
This influence of conscientiousness on longevity was found to be as large or larger than many better known factors affecting longevity, such as socio-economic status.
Among the sub-factors of conscientiousness, it was ambition and discipline that were particularly important for longevity, whereas responsibility and self-control were less important.
Past research has shown that people who are more conscientious are less likely to drink or smoke heavily but health behaviours aren't the whole story. For example, a previous study by the same research team found that conscientiousness measured in childhood predicted longevity over a 70-year period, regardless of whether the cause of death was health-related or not.
Kern said it's possible that as well as affecting health behaviours, conscientiousness also influences the kind of people we end up mixing with and the situations we find ourselves in. The researchers said that personality factors are too often ignored in a
medical context and that their findings could one day have practical implications. "There is some evidence that people can become more conscientious, especially as they enter stable jobs or good marriages," Kern said. "We think our findings can challenge people to think about their lives and what may result from the actions they do. Even though conscientiousness cannot be changed in the short term, improvements can emerge over the long run as individuals enter responsible relationships, careers, and associations."
Margaret L. Kern, Howard S. Friedman (2008). Do conscientious individuals
live longer? A quantitative review. Health Psychology, 27 (5), 505-512.
Author weblink: http://www.faculty.ucr.edu/~friedman/
jueves, julio 22, 2010
The links between bloggers' personalities and their use of wordsYou can tell a person's personality from the words they use. Neurotics have a penchant for negative words; agreeable types for words pertaining to socialising; and so on. We know this from recordings of people's speech and from brief writing tasks. Now Tal Yarkoni has extended this line of research to the blogosphere by analysing the content of 694 blogs - containing an average of 115,000 words written over an average period of about two years - and matching this with the bloggers' (predominantly female; average age 36) answers to online personality questionnaires.Some commentators have suggested that the internet allows people to present idealised versions of themselves to the world. Contrary to that idea, Yarkoni found that bloggers' choice of words consistently related to their personality type just as has been found in past offline research.More neurotic bloggers used more words associated with negative emotions; extravert bloggers used more words pertaining to positive emotions; high scorers on agreeableness avoided swear words and used more words related to communality; and conscientious bloggers mentioned more words with achievement connotations. These were all as expected. More of a surprise was the lack of a link between the Big Five personality factor of 'openness to experience' and word categories related to intellectual or sensory experience. Instead openness was associated with more use of prepositions, more formal language and longer words.The sheer size of the data set at Yarkoni's disposal allowed him to look not only at links between personality factors and broad word categories (as past research has done) but to also zoom in on the usage of specific words. Among the most strong and intriguing correlations were: Neuroticism correlated with use of 'irony' and negatively correlated with 'invited'; Extraversion correlated with 'drinks' and negatively correlated with 'computer'; Openness correlated with 'ink'; Agreeableness with 'wonderful' and negatively correlated with 'porn'; and Conscientiousness correlated with 'completed' and negatively correlated with 'boring'.'The results underscore the importance of studying the influence of personality on word use at multiple levels of analysis,' Yarkoni concluded, 'and provide a novel approach for refining existing categorical word taxonomies and identifying new and unexpected associations with personality.'_________________________________Yarkoni, T. (2010). Personality in 100,000 Words: A large-scale analysis of personality and word use among bloggers. Journal of Research in Personality, 44 (3), 363-373 http://dx.doi.org/10.1016/j.jrp.2010.04.001Author weblink: http://talyarkoni.com/
lunes, julio 05, 2010
Memory performance boosted while walkingPsychologists usually think of attention as a limited resource. The more of it you use on one task, they say, the less you have left over for others. Supporting this, countless studies have shown that performance deteriorates under dual-task versus single-task conditions. But what if, rather than having one pool of attention to share around, we have multiple pools for fueling different types of activity. By this account, if two tasks are different enough from each other, there should be no performance decrement under dual-task conditions. That's exactly what Sabine Schaefer has shown in a new study that looks at memory performance whilst walking. In fact Schaefer's research goes further, showing that memory performance is actually superior whilst walking compared with sitting down.Schaefer's team had 32 nine-year-olds and 32 adults (average age 25) complete the N-back working memory task in three conditions: walking on a treadmill at their own chosen speed; walking on a treadmill at a set speed chosen by the researchers; or sitting down. The N-back task requires that participants listen to a stream of numbers and indicate, in the easiest version, whenever the current number was the same as the number one back. For more difficult versions, it's a repeat of a number further back in the stream that must be spotted.The headline finding was that the working memory performance of both age groups improved when walking at their chosen speed compared with when sitting or walking at a fixed speed set by the researchers. This was especially the case for more difficult versions of the working memory task, and was more pronounced among the children than the adults. So, this would appear to be clear case of mental performance actually being superior in a dual-task situation.Why should the secondary task of walking aid, rather impair, mental performance? The researchers aren't sure of the mechanism, but they think the attentional pool tapped by a sensori-motor task like walking is likely separate from the attentional pool tapped by working memory. Moreover, physical activity increases arousal and activation, 'which then can be invested into the cognitive task,' they said.What about the fact that memory performance wasn't improved when participants walked on the treadmill at a speed set by the researchers? The set walking speed was actually substantially slower than the participants' preferred speed so one possibility is that it wasn't rigorous enough to provide the increased arousal that could be beneficial to memory. Alternatively, perhaps the challenge of walking at a set speed is cognitively demanding, tapping the same attentional pool needed for the memory task.Schaefer's team speculated that a useful application of their finding could be in relation to childhood ADHD. '...[H]yperactive children might also be able to profit from some type of consistent movement that does not require much attention, even though it is often argued that those children have more problems than healthy controls when they have to divide their attention between two concurrent tasks.'_________________________________
Schaefer, S., Lovden, M., Wieckhorst, B., & Lindenberger, U. (2010). Cognitive performance is improved while walking: Differences in cognitive-sensorimotor couplings between children and young adults. European Journal of Developmental Psychology, 7 (3), 371-389 http://dx.doi.org/10.1080/17405620802535666
Author weblink: http://ht.ly/246XX
domingo, julio 04, 2010
The bloggers behind the Psychology BlogsBlogging has emerged as a powerful medium in recent years and nowhere is this more evident than in psychology and neuroscience. But who are the people behind these increasingly influential blogs? What are their motives and what advice do they have for aspiring bloggers? To find out, the Research Digest caught up with a handful of the world's leading psych bloggers: Jacy Young of Advances in the History of Psychology; Jesse Bering of Bering in Mind; Anthony Risser of BrainBlog; David DiSalvo of Brainspin & Neuronarrative; Petra Boynton of Dr Petra; Vaughan Bell of Mind Hacks; Mo Costandi of Neurophilosphy; David Dobbs of Neuron Culture; Neuroskeptic of Neuroskeptic; Hesitant Iconoclast of Neurowhoa!; Scarlett de Courcier of Ramblings of an Academic Petrolhead, Paracademia and 28 others; Dave Munger of Research Blogging and Cognitive Daily; and Wray Herbert of We're Only Human & Full Frontal Psychology.To read their answers visit: http://www.bps.org.uk/bloggers
sábado, julio 03, 2010