Sunday, January 18, 2009

Left-handers not right in the head?

There is a longer summary of the findings below here. There are plenty of studies showing Left-handedness as a brain abnormality but the story below seems to go beyond what the journal article actually shows. Just the fact that it concerns females only is, for instance, not mentioned. The study is Wright, L., Hardie, S.M., & Wilson, K. (2009). "Handedness and Behavioural Inhibition: Left-handed females show most inhibition as measured by BIS/BAS self-report". Personality and Individual Differences, 46, 20 - 24.. One would think that self-reports were a rather poor substitute for direct measurement in this case too. I have probably grumbled enough about the study already but I feel a slight personal involvement with it because I too have had lots of articles published in the selfsame journal. So let me go on to make the further rather obvious point that attributing the effects to brain differences may be correct but the findingds do not show that. The results could equally well be attributed to socialization effects. Leftists might be more hesitant simply because they know they are different

LEFT-handed people make up only 10 per cent of the population, but they are more likely to be inhibited, anxious, shy and embarrassed than right-handed ones. This is according to researchers at the University of Abertay in Dundee, Scotland who compared lefties and right-handers.

The participants were given a behavioral test that assesses personal restraint and impulsiveness. The results showed that left-handers are more likely to feel anxiety, shyness or embarrassment about doing or saying what they want. Left-handers were more likely to agree with statements such as "I worry about making mistakes" and "Criticism or scolding hurts me quite a bit."

The findings could be due to wiring differences between the brains of left- and right-handers, said study leader Dr Lynn Wright. "Left-handers are more likely to hesitate, whereas right-handers tend to jump in a bit more," Wright said. "In left-handers, the right half of the brain is dominant, and it is this side that seems to control negative aspects of emotion. In right-handers, the left brain dominates."


'Marilyn Monroe' hormone discovered

The sample is a very limited one for such large generalizations and the possibility of other things mediating a hormone/behaviour correlation seems not to have been considered

SCIENTISTS have identified the Marilyn Monroe hormone that is linked to an hour-glass body shape in women, and also an increased desire to trade-up to new men. Women who have high levels of oestradoil also show elevated confidence and a greater inclination to have sex outside of their current relationship, according to the US-based research. The ovarian steroid hormone is also associated with having a symmetrical face, large breasts and a low waist-to-hip ratio.

"Marilyn Monroe is actually a really good example of a woman who was almost certainly high in oestradoil," Australian sexologist Dr Frances Quirk said in response to the research. "She was a classic hour-glass figure and because of her relationship pattern - she was a serial monogamist. "Her relationships last three or four years or slightly longer, and if you look at the men she had relationships with, they increased in status."

The University of Texas study took in 52 young women, aged 17 to 30, and checked their oestradoil levels using a saliva swab. They were asked to rate themselves on perceived desirability, quizzed on their sexual motivations and also their inclinations relating to their current relationship. An independent group also assessed photographs of the women to provide an external assessment of their attractiveness. "High-oestradiol women were considered significantly more physically attractive by themselves and others," the study, published in the journal Biology Letters, concluded. "These women reported somewhat lower levels of satisfaction with and commitment to their primary partners, and a significantly greater likelihood ... of becoming acquainted with new potential mates."

The study found while high-oestradiol women reported being "significantly more likely" to have a serious affair, they did not indicate a greater likelihood of having "brief sexual encounters". They favour long-term relationships but are "not easily satisfied by their long-term partners and are especially motivated to become acquainted with other, presumably more desirable, men".

Dr Quirk, Associate Professor at James Cook University, said because of these traits, high-oestradoil women "may also be the sort of women that other women don't like too much".


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