Month: April 2008

‘Blind to change’ or just ‘mostly blind’?

The New York Times Science section has a recent article, Blind to Change, Even as It Stares Us in the Face, by Natalie Angier (you can access it without charge by signing up to their site). The article follows along some of the lines laid out by Jeremy Wolfe of Harvard Medical School, at a symposium on Art and Neuroscience.

Angier discusses Wolfe’s use of Ellsworth Kelly’s ‘Study for Colors for a Large Wall’ to illustrate what is typically called ‘change blindness’: ‘the frequent inability of our visual system to detect alterations to something staring us straight in the face.’ Kelly’s painting is an 8×8 grid of coloured squares, and Wolfe apparently showed repeatedly slides of the picture, sometimes with the colours of squares altered. When he first showed the slide, Angier writes: ‘We drank it in greedily, we scanned every part of it, we loved it, we owned it, and, whoops, time for a test.’ After the test, when the audience was thoroughly uncertain about its ability to recall even the basic patterns of colours; ‘By the end of the series only one thing was clear: We had gazed on Ellsworth Kelly’s masterpiece, but we hadn’t really seen it at all,’ Angier reports.

Change blindness is a fun phenomenon to put into research design. Researchers get away with some really amazing manipulations without their subjects recognizing them. Some experiments report that subjects fail to notice, as Angier details, whole stories of buildings disappearing or that ‘one poor chicken in a field of dancing cartoon hens had suddenly exploded.’

Dr. Wolfe also recalled a series of experiments in which pedestrians giving directions to a Cornell researcher posing as a lost tourist didn’t notice when, midway through the exchange, the sham tourist was replaced by another person altogether.

I’ve also seen discussions of experiments in which subjects watched a videotape and failed to notice a guy in a gorilla suit walking through the middle of the video because they were asked to pay attention to other details.

But is it that we’re blind to change, or that we just trust the world to remember for us, and we’re really good at getting the information we need?
Continue reading “‘Blind to change’ or just ‘mostly blind’?”

Encephalon at Of Two Minds

The most recent edition of the brain sciences blog carnival, Encephalon, is being hosted on the blog, Of Two Minds. Encephalon Goes to Paris (Hilton) includes a couple of references to work here on Neuroanthropology, but we do get called out on our severe reservations about twin studies (ooooo… don’t get me started…).

This won’t be news to many of you. In fact, a fair few of the visits we’ll get over the next few days will probably come from Encephalon-related browsers, but if you don’t already know about it, there’s a pile of interesting material in this edition. I won’t even attempt to summarize all the interesting stuff that you’ll find links to on everything from video games to synesthesia to the history of lithium to olfaction and sensing danger. If you’re not visiting here from there, you may want to pay a visit.

Obesity: Mortality, Activity and More

So tomorrow is the big lecture covering some of the biology of obesity.  My attempt to provide a more comprehensive and better integrated view than Kolata’s Rethinking Thin, at least from an anthropological view (which includes both biological and cultural viewpoints, and for me, also brings in a qualitative focus on people’s experiences and behaviors).  Tonight I will cover three topics—the health risks of obesity, the role of activity and exercise in weight, and the mind vs. metabolism debate.  These complement previous posts on the Behavioral Biology of Obesity and Obesity and Genetics. 

Being fat kills, right?  That’s the predominant health message of the past decade or so.  Extra weight is as bad as smoking, and should be as vilified.  There’s just one problem.  The science doesn’t back up such a blanket statement.  Right now it looks like having a few (yes, a few) extra pounds is actually healthier than being too skinny, at least at the population level. 

Some of Kolata’s best writing tells us about the work of Katherine Flegal and colleagues, who used sophisticated population data and statistical work to ask a basic question, What is the health risk of being overweight?  Based on research published in 2005 by the Journal of American Medical Association, Flegal found that individuals who were overweight but not obese (a BMI between 25 and 30) had lower mortality rates than people considered “normal” by BMI standards (86,000 deaths less than expected).  For people with a BMI of 30 or greater, obesity accounted for 112,000 deaths per year, a very large number but quite less than previous estimates of around 400,000 per year. 

This research is well-summarized in this Medical News Today article, which states “the net U.S. death toll from excess weight is 26,000 per year. By contrast, researchers found that being underweight results in 34,000 deaths per year.”  Flegal and colleagues have gone on to provide a wealth of evidence, their own and others’, that confirms their basic point that being overweight is different from being obese, and less risky than generally assumed in the highly charged moral debate in the United States.  As always, there is criticism and controversy over the methods and results, which are well summarized in this piece at Partnership for Prevention and also at The Center for Consumer Freedom. 

Continue reading “Obesity: Mortality, Activity and More”