Science Friday: How you count on your fingers says what about your brain? | Why humans laugh? | Edison’s car battery is back
Put down your coffee for a moment. Now, without thinking about it too much, use your hands to count to 10.
How did you do it? Did you start with the left hand, or the right? Did you begin counting on a thumb, or with a pinkie? Maybe you started on an index finger? And did you begin with a closed fist, or an open hand?
If you're European, there's a good chance you started with closed fists, and began counting on the thumb of the left hand. If you're from the Middle East, you probably also started with a closed fist, but began counting with the little finger of the right hand.
Most Chinese people, and many North Americans, also use the closed-fist system, but begin counting on an index finger, rather than the thumb. The Japanese typically start from an open-hand position, counting by closing first the little finger, and then the remaining digits.
In India, it's common to make use of finger segments to get as many as 20 counts from each hand. It's even been reported that the Amazonian Pirah people don't use their fingers to count at all.
Finger counting feels as natural as breathing – but it's not innate, or even, apparently, universal. There are actually many different techniques, and they are culturally transmitted.
In the latest issue of Cognition, German researchers Andrea Bender and Sieghard Beller argue that the extent of cultural diversity in finger-counting has been hugely underestimated. They also say that by studying finger counting techniques, we could better understand how culture influences cognitive processes – particularly mental arithmetic.
- Laughter is a strong, positive vocal expression of emotion, which is found throughout human cultures and also in many mammals. Although you might think of laughter as something people do when they hear jokes, in fact we laugh most often when we are talking with our friends. Indeed, for both rats and humans, laughter first appears in babies when they interact with their caregivers.
Robert T. Gonzalez
- In 1901, Thomas Edison developed the recharcheable nickel-iron battery, a technology he hoped to see implemented in electric cars. But a slow rate of energy output and slower charging time saw it superseded by lead-acid and lithium-ion batteries in standard and electric cars alike.
Now, more than a century after it was first developed, the "Edison battery" has been reborn — and it's faster, cheaper and more powerful than ever. Will it find new life in the electric vehicles of tomorrow?
The original Edison battery was lauded for its endurance and reliability, but the power supply had significant drawbacks. The typical nickel-iron battery requires several hours to charge, and the rate of discharge is prohibitively slow.
To address these shortcomings, a team of researchers led by Stanford University chemist Honjie Dai decided to give Edison's ideas an upgrade by future-fitting the inventor's early 20th century design with 21st century nanotechnology. The result was a revamped Edison battery capable of charging and discharging nearly 1,000 times as fast as the original.
Bringing new life to an old idea
The researchers' redesign relies on some clever carbon chemistry, which is published in the latest issue of Nature Communications and summarized in the diagram featured here [click to enlarge]. Carbon is often used to improve electrical conductivity in electrodes; the issue, explains lead author Hailiang Wang, is using that carbon to its full potential:
In conventional electrodes, people randomly mix iron and nickel materials with conductive carbon. Instead, we grew nanocrystals of iron oxide onto graphene [single-molecule-thin sheets of carbon arranged in a honeycomb lattice], and nanocrystals of nickel hydroxide onto carbon nanotubes [cyclinders of carbon molecules, also arranged in a honeycomb lattice].
The resulting chemical bonds had a remarkable effect on battery performance. "Coupling the nickel and iron particles to the carbon substrate allows electrical charges to move quickly between the electrodes and the outside circuit," explained Dai. "The result is an ultrafast version of the nickel-iron battery that's capable of charging and discharging in seconds."