Debunked: “Right-Brain” vs. “Left-Brain” Personalities

For years in popular culture, the terms “left-brained” and “right-brained” have come to signify disparate personality types, with an assumption that some people use the right side of their brain more, (those who are supposedly more creative/artistic) while some use the left side more (those who are more logical/analytical). But newly released research findings from University of Utah neuroscientists assert that there is no evidence within brain imaging that indicates some people are right-brained or left-brained:

Following a two-year study, University of Utah researchers have debunked that myth through identifying specific networks in the left and right brain that process lateralized functions. Lateralization of brain function means that there are certain mental processes that are mainly specialized to one of the brain’s left or right hemispheres. During the course of the study, researchers analyzed resting brain scans of 1,011 people between the ages of seven and 29. In each person, they studied functional lateralization of the brain measured for thousands of brain regions — finding no relationship that individuals preferentially use their left -brain network or right- brain network more often.

Following a two-year study, University of Utah researchers have debunked that myth through identifying specific networks in the left and right brain that process lateralized functions. Lateralization of brain function means that there are certain mental processes that are mainly specialized to one of the brain’s left or right hemispheres. During the course of the study, researchers analyzed resting brain scans of 1,011 people between the ages of seven and 29. In each person, they studied functional lateralization of the brain measured for thousands of brain regions — finding no relationship that individuals preferentially use their left -brain network or right- brain network more often.

“It’s absolutely true that some brain functions occur in one or the other side of the brain. Language tends to be on the left, attention more on the right. But people don’t tend to have a stronger left- or right-sided brain network. It seems to be determined more connection by connection, ” said Jeff Anderson, M.D., Ph.D., lead author of the study, which is formally titled “An Evaluation of the Left-Brain vs. Right-Brain Hypothesis with Resting State Functional Connectivity Magnetic Resonance Imaging.” It is published in the journal PLOS ONE this month.

From the paper’s abstract:

Lateralized brain regions subserve functions such as language and visuospatial processing. It has been conjectured that individuals may be left-brain dominant or right-brain dominant based on personality and cognitive style, but neuroimaging data has not provided clear evidence whether such phenotypic differences in the strength of left-dominant or right-dominant networks exist. We evaluated whether strongly lateralized connections covaried within the same individuals. Data were analyzed from publicly available resting state scans for 1011 individuals between the ages of 7 and 29. For each subject, functional lateralization was measured for each pair of 7266 regions covering the gray matter at 5-mm resolution as a difference in correlation before and after inverting images across the midsagittal plane. The difference in gray matter density between homotopic coordinates was used as a regressor to reduce the effect of structural asymmetries on functional lateralization. Nine left- and 11 right-lateralized hubs were identified as peaks in the degree map from the graph of significantly lateralized connections. The left-lateralized hubs included regions from the default mode network (medial prefrontal cortex, posterior cingulate cortex, and temporoparietal junction) and language regions (e.g., Broca Area and Wernicke Area), whereas the right-lateralized hubs included regions from the attention control network (e.g., lateral intraparietal sulcus, anterior insula, area MT, and frontal eye fields). Left- and right-lateralized hubs formed two separable networks of mutually lateralized regions. Connections involving only left- or only right-lateralized hubs showed positive correlation across subjects, but only for connections sharing a node. Lateralization of brain connections appears to be a local rather than global property of brain networks, and our data are not consistent with a whole-brain phenotype of greater “left-brained” or greater “right-brained” network strength across individuals. Small increases in lateralization with age were seen, but no differences in gender were observed.

So while there are more creative/artistic people in the world, this study purports that the active parts of the brain do not account for said personality traits. You learn something new every day, right?

On Predicting the Person You’ll Be

John Tierney offers a summary from a recent study published in Science about our ability to predict our future tastes and personality changes:

[W]hen asked to predict what their personalities and tastes would be like in 10 years, people of all ages consistently played down the potential changes ahead.

Thus, the typical 20-year-old woman’s predictions for her next decade were not nearly as radical as the typical 30-year-old woman’s recollection of how much she had changed in her 20s. This sort of discrepancy persisted among respondents all the way into their 60s.

And the discrepancy did not seem to be because of faulty memories, because the personality changes recalled by people jibed quite well with independent research charting how personality traits shift with age. People seemed to be much better at recalling their former selves than at imagining how much they would change in the future.

And another interesting bit:

When asked about their favorite band from a decade ago, respondents were typically willing to shell out $80 to attend a concert of the band today. But when they were asked about their current favorite band and how much they would be willing to spend to see the band’s concert in 10 years, the price went up to $129. Even though they realized that favorites from a decade ago like Creed or the Dixie Chicks have lost some of their luster, they apparently expect Coldplay and Rihanna to blaze on forever.

Japan, Blood Type, and Superstition

It is a widespread belief in Japan that character is linked to blood type, as this BBC Magazine story details:

According to popular belief in Japan, type As are sensitive perfectionists and good team players, but over-anxious. Type Os are curious and generous but stubborn. ABs are arty but mysterious and unpredictable, and type Bs are cheerful but eccentric, individualistic and selfish.

About 40% of the Japanese population is type A and 30% are type O, whilst only 20% are type B, with AB accounting for the remaining 10%.

This seems crazy:

A whole industry of customised products has also sprung up, with soft drinks, chewing gum, bath salts and even condoms catering for different blood groups on sale.

Seems to me like you can revel in or excuse your personality traits on your blood type. When it is working for you, great. But when something bad happens, blame your blood type.

Twitter, Facebook, and Personality Type

What can one glean of someone’s personality type based on preference for Twitter vs. Facebook usage? David Hughes at Manchester Business School and his colleagues surveyed 300 people online and were scored on the “big five” personality factors of extraversion, neuroticism, conscientiousness, openness, and agreeableness. The study’s findings are summarized here:

People who used Facebook mostly for socialising tended to score more highly on sociability and neuroticism (consistent with past research suggesting that shy people use the site to forge social ties and combat loneliness). Social use of Twitter correlated with higher sociability and openness (but not neuroticism) and with lower scores on conscientiousness. This suggests that social Twitter users don’t use it so much to combat loneliness, but more as a form of social procrastination

What about using the sites as an informational tool? There was an intriguing divergence here. People who said they used Facebook as an informational tool tended to score higher on neuroticism, sociability, extraversion and openness, but lower on conscientiousness and “need for cognition”. Informational users of Twitter were the mirror opposite: they scored higher on conscientiousness and “need for cognition”, but lower on neuroticism, extraversion and sociability. The researchers interpreted these patterns as suggesting that Facebook users seek and share information as a way of avoiding more cognitively demanding sources such as journal articles and newspaper reports. Twitter users, by contrast, use the site for its cognitive stimulation – as a way of uncovering useful information and material without socialising (this was particularly true for older participants).

Finally, what about people’s overall preference for Twitter or Facebook? Again, people who scored higher in “need for cognition” tended to prefer Twitter, whilst higher scorers in sociability, neuroticism and extraversion tended to prefer Facebook. Simplifying the results, one might say that Facebook is the more social of the two social networking sites, whereas Twitter is more about sharing and exchanging information. 

It’s an interesting study, though I would have liked to see a sample size of a magnitude higher, and more balanced with the female-male ratio.