Perception


Robert Krulwich, NPR’s science reporter, is always interesting, but the report below is absolutely fascinating: people cannot walk in straight lines without visual cues.  And researchers don’t know why.  (Check the link for a fascinating video.)

Try this: Put a blindfold on someone, take them to a park or a beach or a meadow and ask them to walk for as long as they can in a straight line. Then watch what happens:

So why, when blindfolded, can’t we walk straight? There is still no good answer.  Jan Souman, a research scientist in Germany, co-wrote a paper last year about this human tendency to walk in circles.

Walking Blindfolded

Jan Souman/ Max Planck Institute for Biological Cybernetics 

Like Asa Schaeffer in our animation, he blindfolded his subjects (if you can call what he did to them “blindfolding;” it’s more like head wrapping) and told them to try to walk straight for up to an hour.

Google Earth Image

Jan Souman/Max Planck Institute for Biological Cybernetics 

They did this in the Sahara Desert. They did it on a beach. As usual, the blindfolded subjects could not keep to a straight line.

Souman also ran the experiment in Bienwald forest in Germany, apparently without blindfolds. As the subjects walked, Jan mapped where they went. Here’s a sample of his results.

Those two red dots mark the start of several walks. He ran these experiments over a series of days.

The Weather Matters

When the sky was cloudy and visibility low (blue lines), the walkers (labeled KS, PS and RF) were unable to stay straight and began to turn.

When it was sunny (yellow lines), the walker (labeled SM) was able to keep a steady and rather lengthy straight line.

Humans, apparently, slip into circles when we can’t see an external focal point, like a mountain top, a sun, a moon. Without a corrective, our insides take over and there’s something inside us that won’t stay straight.

But Why?

In our radio broadcast, Jan and I  explore (just hit the “Listen” button on this page) possible explanations for this tendency to slip into turns. Maybe, I suggest, this is a form of left or right handedness where one side dominates the other? Or maybe this is a reflection of our left and right brains spitting out different levels of dopamine? Or maybe it’s stupidly simple: Most of us have slightly different sized legs or slightly stronger appendages on one side and this little difference, over enough steps, mounts up?

Wrong, wrong and wrong, Jan says. He’s tested all three propositions (the radio story describes the details) and didn’t get the predicted results. There is, apparently, no single explanation for this phenomenon. He is working on a multi-causal theory.

So like walking in circles, we finish where we started: with Asa Schaeffer’s very simple field studies, his graceful pencil lines (especially when our animator Benjamin Arthur gives them beautiful motion) posing the puzzle: How can we be turning and turning and not know it?

Via: http://www.npr.org/blogs/krulwich/2010/11/03/131050832/a-mystery-why-can-t-we-walk-straight

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Scientists have confirmed a rather simple tip for looking younger that doesn’t require plastic surgery, Botox or expensive anti-wrinkle creams: Hang out with old people.

We underestimate the age of a person in his or her 30s if we have previously looked at pictures of older people, researchers found.

They also found it worked in reverse: We overestimate ages after looking at pictures of younger people.

“People are actually quite good at guessing the age of the person next to them,” said study researcher Holger Wiese, of Jena University in Germany. But in their experiment, “we are able to change the subjective perception of a face.”

The researchers asked 24 young adults to look at pictures of 15 female and 15 male faces. Each image was doctored to show what the person would look like in his or her 20s, 30s, 40s, 50s, 60s and 70s.

The volunteer were systematically wrong at estimating other people’s ages after they had looked intensely at faces of people of a specific age group.

For example, if many faces of elderly people were shown on the computer first, followed by the face of a middle-age person, the volunteers made out the middle-age person to be substantially younger than he or she was. But after first studying younger faces, the volunteers estimated the middle-age person as being substantially older.

The effect was strongest if the series of older faces and subsequent image of a younger face were the same gender, the study showed.

The results held regardless the viewers’ age and gender, the researchers said. They said they did not yet know how long the effect lasts.

Via: http://news.yahoo.com/s/livescience/20110107/sc_livescience/howtolookyoungerhaveolderfriends

Referees are more likely to make foul calls when they see the action moving from right to left, or leftward, according to a new study by brain researchers at the University of Pennsylvania.

Twelve varsity soccer players were shown identical images of plays, with the only difference being that some viewed the images flipped horizontally, so there were right-to-left and left-to-right versions. The participants that saw the action as moving from right-to-left were statistically more likely to call a foul.

Other studies have shown that the direction in which people read and write leads to a bias toward rightward or leftward action. One study found that Italians were more likely to view a soccer goal as “stronger, faster and more beautiful” when it was presented with a left-to-right trajectory rather than the other way around, and that Arabic speakers showed the opposite bias.

I’m not certain that the studies described really prove the claim — the experiments should be run with actual referees (who may minimize the directional bias by training or practice).  In any case, they’re interesting and a valuable reminder of how subtly biases can exist in our perceptions.

via Wired Science – News for Your Neurons | Wired.com.