Science News - December 3, 2011

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Skateboarders
rock at physics

Below is a side view of a ball that could roll down either the red or blue ramp. Which route do you think would result in it arriving at the finish line first?

By Bruce Bower

Skateboarders know some righteous physics, dude. That’s because their hair-raising rides provide body-based insights into slope speeds that often elude others.

A ball travels faster down a relatively long incline angling steeply downward in two sections separated by a flat stretch compared with a shorter incline angling downward modestly but without changing slope. Most people don’t realize this, but skateboarders often do, said psychologist Michael McBeath of Arizona State University. Skateboarders call on motor memory to determine intuitively that a sharp early descent creates a speed advantage, he reported November 5.

Of 122 college students shown drawings of a longer, steeply angled incline

START

Shredding physics

When asked to solve the physics problem illustrated here, skateboarders were more likely than others to answer correctly: the ball will reach the finish faster if it rolls down the blue ramp. Only 27 percent of college students got it right, but 61 percent of skateboarders did.

FINISH

and a shorter, straight incline, only 27 percent realized that a ball would travel faster down the longer path, McBeath and his colleagues found. Intriguingly, a few students known to be avid skateboarders solved the problem correctly.

McBeath’s team then recruited
41 volunteers — mostly males who had
skateboarded for anywhere from about
six months to 15 years— at a nearby
skateboarding park. One area of the park
contained adjacent slopes, one flat and
one with a pair of bumps, much as in the
classroom problem. Participants told to
skateboard as fast as possible down one
of these slopes picked the bumpy path
on 75 percent of runs. The bumpy slope
consistently produced faster rides.

Listening gets in the way of hearing
tracking a conversation can block out peripheral sounds

By Bruce Bower

Good listeners inadvertently turn a deaf ear to unexpected sounds. Attending closely to a conversation creates a situation in which unusual, clearly audible background utterances frequently go totally unheard.

This finding takes the famous “ invisible gorilla effect” from vision into the realm of hearing, psychologist Polly Dalton of the University of London reported November 4.

More than a decade ago, researchers
observed that about half of volunteers
watching a videotape of people passing
a basketball fail to see a gorilla-suited
person walking through the group if
the viewers are instructed to focus on
counting how many times the ball gets
passed (SN: 5/21/11, p. 16).

Participants were assigned to pay attention either to the men’s or the women’s conversation.

Nearly all of the volunteers following the women and almost one-third of those tracking the men didn’t hear gorilla man at all. The intrusive ape passed closer to the conversing men in the acoustic scene, partly explaining why his voice was detected more often by those listening to the men, Dalton suggested.

Psychologist Jeremy Wolfe of Harvard Medical School said he suspects that, given the power of focused attention to erase peripheral sounds, volunteers would fail to hear gorilla man even if the unseen primate made gorilla sounds or played a flute.