5 February 2011 | NewScientist | 21

against an entry written by a single worker, as well as one taken from the Simple English Wikipedia, a version of Wikipedia that uses simpler grammar and fewer words than the full version of the online encyclopedia. They rated it more highly than the individual version and on a par with the Wikipedia entry. The team will present their work in May at the Conference on Human Factors in Computing in Vancouver, Canada.

Jeffrey Nickerson of the Stevens Institute of Technology in Hoboken, New Jersey, is trying to break down complex tasks of a different kind. He asked Mechanical Turk workers to come up with designs for a children’s chair. Other workers rated the drawings, and those most highly rated went into a second round in which workers attempted to combine the best elements from pairs of the drawings. Nickerson repeated this process of rating and recombination, which he calls a “human genetic algorithm”, twice more. He too will present his work at the Vancouver conference in May.

From a practical standpoint, these complex crowd-sourced processes are still in their infancy. Researchers are interested in trying to design graphics and write advertising copy in this way, but it’s still not clear which complex tasks can be broken down into ones that can be performed by an unskilled labour force. And if the method continues to gain in popularity, questions of whether Mechanical Turk workers are paid fairly – and whether they should be protected by labour laws – will have to be answered.

The results from Nickerson’s experiment are not good enough to be made into chairs, says John Nastasi, an architect at Stevens who worked with Nickerson on the project. But some of the designs, like a “whimsical” chair with feet that looked like human feet, show that the approach has potential, he says. n

Woodpecker’s head inspires shock absorbersWHEN aircrash investigators of the future retrieve a flight recorder from the wreckage of a plane they may have the woodpecker to thank for the survival of the flight data.

A woodpecker’s head experiences decelerations of 1200g as it drums on a tree up to 22 times per second. Humans are often left concussed if they experience 80 to 100g, so how the woodpecker avoids brain damage was unclear.

So Sang-Hee Yoon and Sungmin Park of the University of California,

Berkeley, studied video and CT scans of the bird’s head and neck and found that it has four structures that absorb mechanical shock. These are its hard-but-elastic beak; a sinewy and springy tongue-supporting structure called the hyoid; an area of spongy bone in its skull; and little space between the skull and the brain for cerebrospinal fluid, which transmits vibrations.

Finding artificial analogies for all these factors, the pair built a shock absorbing system that works in a

SOURCE: DIGIM

ORPH.ORG

A woodpecker drums a tree as fast as 22

beats a second, creating decelerations of up to

1200g. While drumming,it keeps its beak

perpendicular to the tree

Beak/Outer case

SHOCK ABSORBER

WOODPECKER

The woodpecker’s beak is extremely strong and does not bend or fracture

A steel metal enclosure is the �rst line of defence for the shock absorber

Hyoid/Elastic layerThis solid, springy and bony

support for the tongue, unique to the woodpecker, evenly

distributes loads from vibration

Mimicked in the shock absorber by a load-spreading layer of rubber

Spongy bone/Glass beadsThe bone’s porous structure

stops low frequency vibrations from reaching the bird’s brain

A layer of closely packed glass beads helps absorb shock and

protect the microelectronics

Skull/Aluminium layerThere is little room between the skull and the brain for cerebrospinal �uid, reducing the transmission of vibrations

A second layer of metal provides extra protection to the microelectronics

Brain/ElectronicsThere are four systems in place to protect the woodpecker’s brain

These have been copied in a new shock absorber to protect sensitive electronics

For daily technology stories, visit www.NewScientist.com/technology

similar way (see diagram, below). To test their system, they placed it inside a bullet and used a large 60-millimetre airgun to fire it at a metal wall. They found the electronics ensconced within it were protected against shocks of up to 60,000g. (Bioinspiration and Biomimetics, DOI: 10.1088/1748- 3182/6/1/016003).

As well as protecting flight recorders, the shock absorber could also be used in “bunker-busting” bombs and crash protection in motorsport. Paul Marks n

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