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Can Bigger Brains Manage More Relationships?

Professor Robin Dunbar is best known for his work related to how many stable social relationships the human brain can manage. In earlier research, he argued that the optimal number of active relationships is 150 -- now famously known as the "Dunbar Number."

Dunbar is once again delving into the brain's social capacity, but this time he's focused on the size of the orbital prefrontal cortex (aka, the frontal lobe), the part of the brain involved in high-level thinking that sits just above our eyes.  Dunbar and collegues have found that the size of this brain area correlates with the number of friendships a person is capable of managing.

The study suggests that we need to employ a set of cognitive skills to maintain a large number of friends, known in psychology circles as "mentalizing" or "mind-reading"-- an ability to understand what another person is thinking, which is crucial to our ability to handle our complex social world, including the ability to hold conversations with one another.

According to Professor Dunbar, as reported by Science Daily,'"Mentalizing" is where one individual is able to follow a natural hierarchy involving other individuals' mind states. For example, in the play 'Othello', Shakespeare manages to keep track of five separate mental states: he intended that his audience believes that Iago wants Othello to suppose that Desdemona loves Cassio. Being able to maintain five separate individuals' mental states is the natural upper limit for most adults."

The researchers took brain scans of 40 volunteers to measure the size of the prefrontal cortex. Participants were then asked to make a list of everyone they had had social (not professional) contact with over the previous seven days. They also took a test to determine their competency in mentalizing.

Dunbar adds, "We found that individuals who had more friends did better on mentalizing tasks and had more neural volume in the orbital frontal cortex. Understanding this link between an individual's brain size and the number of friends they have helps us understand the mechanisms that have led to humans developing bigger brains than other primate species. The frontal lobes of the brain, in particular, have enlarged dramatically in humans over the last half million years."

The study was published in The Proceedings of the Royal Academy of Biological Sciences.

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HDL, the "Good" Cholesterol, May Not be So Good After All

The website, The Singularity Hub, is reporting on a study that suggests HDL is not the ally against heart disease that we've been lead to believe it is. From the article:

The revelation that high-density lipoprotein, or HDL, is the “good cholesterol” has suffered a major blow. A meta-studyinvolving over a hundred thousand participants used two different strategies to see if genetic mutations that increased levels of HDL also decreased risk for heart disease. In both cases the answer was a resounding no. The researchers were shocked when they saw the data. Now it’s their turn to shock HDL proponents and drug companies looking to cash in on the HDL craze.

The study, which was published recently in The Lancet, is causing quite a stir in the field. As Dr. James de Lemos, from the University of Texas Southwestern Medical Center, told the New York Times, “I’d say the HDL hypothesis is on the ropes right now.” Dr. de Lemos was not involved in the study.

Read the entire article at The Singularity Hub.

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Why You Don't Like Your Photos -- it's All About Movement 

If you think you look better in person than in photographs, you're probably right.

According to new research by psychologists at the Universities of California and Harvard, most of us succumb to the "frozen face effect" in still photos -- and it's not very flattering.

Here's a brief summary of the study from the excellent British Psychological Society Research Digest:

Robert Post (the study lead) and his colleagues made their findings by asking a handful of participants to rate how "flattering" or "attractive" 20 people looked in two-second video clips and in 1200 static frames taken from those clips. The same faces were consistently rated as more attractive and flattering in the video clips than in the stills.

The research team took pains to figure out the underlying cause of this effect and ran several follow-up experiments. Again from the Digest:

It was found that the same rule held with the videos and stills turned up-side down. The researchers also showed the effect has nothing to do with the videos containing more information: when the "flattering" ratings of an ensemble of multiple stills of a face was compared against ratings of those same stills in a video, once again the video received the more positive ratings. Memory didn't seem to be a factor either -- more or less flattering images weren't remembered any better than average.

So what's going on here?  Why should movement impart greater attractiveness than stillness?  It may all come down to averages. When we see a still photo, our brain processes the attributes of a face as a "one off" -- quite literally, all the brain has to work with is a snapshot, a moment in time when the face was artificially frozen in place.

When someone is moving, the brain captures multiple images of the face and averages them out across various positions. The more the brain captures, the greater the opportunity for the average of those images to appear appealing.  As the Digest article points out, this finding would jibe with previous research suggesting that average faces are judged as more attractive than those with extreme features.

The study was published in the February 2012 issue of the journal Frontiers in Psychology.


Study: Boost Your Brain's White Matter Now for a Sharper Brain Later

Neuroscience News reports on a recent study showing that the key to staying mentally sharp as we age is keeping the brain's white matter robust. White matter is consituited by connections between neurons, so the more "firing and wiring" of neurons we can facilitate by staying mentally challenged through the years, the better off we'll be as our bodies age.  From the article:

According to the findings, joining distant parts of the brain together with better wiring improves mental performance, suggesting that intelligence is not found in a single part of the brain.

However a loss of condition of this wiring or ‘white matter’, the billions of nerve fibres that transmit signals around the brain, can negatively affect our intelligence by altering these networks and slowing down our processing speed.

The research by the University of Edinburgh shows for the first time that the deterioration of white matter with age is likely to be a significant cause of age-related cognitive decline.

The research team used three different brain imaging techniques in compiling the results, including two that have never been used before in the study of intelligence.

Read the entire article at Neuroscience News


Is Wanting What Others Have Hardwired in Our Brains?

Science News has an interesting article about new research suggesting that our desire to have what others have is neurally hardwired in our brains.  From the article:

Copying other people’s desires is a good way to learn about the environment, says study coauthor Mathias Pessiglione of INSERM in Paris. Eating the food that other people eat, for example, is a simple way to avoid food poisoning. But this adaptive feature can break down when desired objects are in short supply.

Pessiglione and his team showed adults one of two videos: a piece of candy sitting on a surface, or a person’s hand reaching toward a different-colored piece of candy. Participants then rated the desirability of each candy they saw. As the mimetic desire theory predicts, people rated the about-to-get-grabbed candy as more desirable. The same effect held for clothes, tools and even toys, the team reports in the May 23 Journal of Neuroscience

Read the entire article at Science News