Testing, not studying, makes for strong long-term memories

Blogging on Peer-Reviewed ResearchIt’s a familiar scene – the wee hours of the morning are ticking away and your head is bent over a stack of notes, desperately trying to cram as much knowledge into your head before the test in the morning.

Exam roomBecause of the way our education system works, this process of hard studying has become almost synonymous with the act of learning, and the inevitable tests and exams that bookend this ordeal merely assess how much information has stuck.

But a new study reveals that the tests themselves do more good for our ability to learn that the many hours before them spent relentlessly poring over notes and textbook. The act of repeatedly retrieving and using learned information drives memories into long-term storage, while repetitive revision produced almost no benefits.

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Not Exactly Rocket Science’s Review of 2007

As another year finishes and it’s been a good one for me. I won a writing award, got to talk to David Attenborough and started a freelancing career. Luckily, the Christmas break has provided some much-needed relaxation so before I launched renewed into 2008, I thought I’d take a look back and pick the favourite stories which I managed to write about over the last year.

This isn’t a list of the biggest or most important breakthroughs; they are simply the stories I enjoyed writing about the most. They represent a mix of quirky results, articles I was proud of, and sheer coolness – my top ten are in green. As always for this site, all stories were written from the actual papers, rather than press releases or other news coverage.

Once again, thanks to everyone who read, commented on, or linked to this site. Hope to see you all in the new year.

Evolution

1) Living optic fibres bypass the retina’s back-to-front structure

The human retina has an ‘incompetent design’ that forces light to cross a tangle of nerves and blood vessels before reaching the light sensors at the back. The mammalian eye has solved this problem by evolving living optic fibres – Muller cells – that funnel light through the messy retina.

2) Orang-utan study suggests that upright walking may have started in the trees

A study in orang-utans suggested that our ancestors may have evolved to walk on two legs while they were still in the trees, using a bipedal stance to traverse thin branches and canopy gaps.

3) Butterflies evolve resistance to male-killing bacteria in record time

It’s always a thrill to see examples of evolution in action. This year, the beautiful blue moon butterfly of Samoa provided just such an example by evolving resistance to a bacteria that was killing off its males within just 10 generations.

4) The evolution of the past tense – how verbs change over time

Evolution’s not just about genes. In a beautifully written paper, Harvard scientists mathematically modelled the evolution of English verbs, showing that irregular verbs become standardised according to an elegantly simple mathematical model.

Animal behaviour

5) Moray eels attack ‘Alien-style’ with second pair of jaws

Even familiar animals can surprise us. Moray eels are common aquarium specimens but scientists only just discovered that they grab prey with a second set of scary Alien-style jaws that launch forwards from the back of the throat

6) Mobs of honeybees suffocate hornets to death

Cyprian honeybees are frequently attacked the formidable Oriental hornet. But the smaller, weaker bees defend themselves by working together. They mob the hornet, prevent it from expanding the breathing apparatus in its abdomen and suffocate it to death.

7) Fake cleaner fish dons multiple disguises

This year, the bluestriped fangblenny emerged as only the second animal that can change colour to mimic different species, depending on whether it wants a meal or protection. Other discoveries showed the strategic ways in which animals use defensive signals – ground squirrels heat up their tails to fool infrared-sensing rattlesnakes (but not other snakes) and cuttlefish flash up startling eye spots only in front of fish that hunt by sight.

Animal intelligence

8] Chimps trump university students at memory task

Chimps took plenty of opportunities to show how intelligent they are, not least by beating human university students at a memory test. Other studies found that chimps make their own spears to hunt bushbabies, pass on new traditions between groups, altruistically help each other out and even had their own equivalent of our Stone Age.

9) Elephants smell the difference between human ethnic groups

Elephants too have demonstrated that they are no slouches in the intelligence department. African elephants can tell the difference between human ethnic groups and react more fearfully to those that hunt elephants.

10) Clever New Caledonian crows use one tool to acquire another

Meanwhile, the astonishing New Caledonian crow showed that it can combine different tools to solve a problem, often on the first go. They are the only animals besides ourselves and the great apes that have shown this ability.

Palaeontology

11) Microraptor – the dinosaur that flew like a biplane

Flying birds evolved from land-bound dinosaurs, but like human aircraft, it seems that they may have gone through a two-wing design. A small feather dinosaur called Microraptor had wings on its legs too and used these to glide from tree to tree.

12) Evidence that Velociraptor had feathers

This year, scientists finally proved that Velociraptor had feathers on its arms, contrary to its makeover in Jurassic Park. Until now, that had always been an educated guess based on its evolutionary relatives, but small mounds of bone – quill knobs – provided conclusive proof.

13) Sabre-toothed cats had weak bites

The fearsome sabre-toothed cat, Smilodon, was found to have a surprisingly weak bite. It’s massive canines weren’t the brute blade of a swordsman, but the precise daggers of an assassin, used to deliver a quick killing blow to prey that was already wrestled to the ground.

Health and medicine

14) Human skin cells reprogrammed into stem cells

In one of the most exciting breakthroughs of the year, two groups of scientists found a way of turning adult human cells back into the stem cells of embryos, bringing us closer towards treating a range of conditions with personalised stem cells. One such technique was used to cure mice of a genetic disease called sickle cell anaemia using stem cells reprogrammed from their own tails.

15) Brain parasite drives human culture

The thought of a microscopic creature controlling our actions isn’t a nice one, but it might be true. The brain parasite, Toxoplasma gondii, affects a huge proportion of the world’s population and could be a potent driving force of human culture.

16) Space flight turns Salmonella into super-bug

Some bad news for astronauts – a NASA study showed that bacteria react to the zero-gravity conditions of space by becoming extra-virulent super-bugs.

17) Human gut bacteria linked to obesity

Obesity may be down to food and exercise, but new research showed that the balance between two groups of bacteria in our digestive systems affects our risk of being fat.

18) Resistance to an extinct virus makes us more vulnerable to HIV

A fascinating study showed that modern infections of HIV may be the price we pay for immunity to an extinct virus. Millions of years ago, we evolved resistance to a virus called pTERV1 that plagued other primates but this adaptation makes us more vulnerable to HIV.

Environment and ecology

19) How biofuels could cut carbon emissions, produce energy and restore dead land

It’s been a big year for biofuels – hailed as a solution to climate change, they have recently been accused to worsening the problem. But amidst the debate, a small paper went unnoticed, which found that cultivating a diverse mix of woody plants, legumes and grasses could produce biofuels in a way that would curb carbon emissions, produce renewable energy, restore unusable agricultural land and improve biodiversity.

20) Is a virus responsible for the disappearing bees?

Since 2006, a mysterious condition known as Colony Collapse Disorder has been causing entire hives of bees across the US and the UK to vanish. This year, a group of scientists finally found the cause – a virus called IAPV.

21) Restoring predator numbers by culling their prey

It’s been a fascinating year for ecology, with several papers showing that changes to food webs can have very unexpected results. A Norwegian case study epitomised this concept by showing that the best way to help out a threatened predator may be to counter-intuitively cull its prey. Along similar lines, other studies found that shark-hunting harms animals at bottom of the food chain.

Genetics and molecular biology

22) An entire bacterial genome discovered inside that of a fruit fly

In one of the most remarkable examples of gene transfer, scientists discovered that a bacteria called Wolbachia has transferred its entire genome into that of a fruit fly. These extreme gene transfers have important consequences for genome-sequencing projects.

23) Molecule’s constant efforts keep our memories intact

One study this year revealed our memories to be more fragile than we thought. Rather than being permanently writ in our minds, they only remain intact thanks to the constant action of a protein called PKMzeta. Block the protein and erase the memories.

24) Discovery of ‘fat gene’ highlights stigma against obese people

Earlier this year, a gene called FTO was identified as an obesity-related gene. More pertinently, it also highlighted the massive societal stigmas faced by obese people and the incredibly poor public understanding of the how genes affect behaviour.

Psychology

25) Why music sounds right – the hidden tones in our own speech

All cultures around the world divide octaves into twelve semi-tones. Now, we know that this is because these musical intervals reflect the sounds of our own speech. They sound right because they match the frequency ratios hidden within the vowels of our languages.

26) Five-month-old babies prefer their own languages and shun foreign accents

It seems even five-month-old infants have strong prejudices – even though they can’t speak themselves, they prefer the sounds of their own languages and people who speak with native accents.

27) Subliminal flag shifts political views and voting choices

Subliminal messages can strongly affect behaviour, as a group of Israeli scientists found. They changed the attitudes of Israeli students to the Israeli-Palestine conflict, and their voting preferences, by showing them the national flag for just 16 milliseconds, not long enough to consciously register.

Neuroscience

28) Simple sponges provide clues to origin of nervous systems

This year, the possible origins of the nervous system were found in the simple sponge, an animal with no nervous system of its own. Sponges carry the genetic components of synapses, which may have been co-opted by evolution as a starting point for proper nerve cells

29) Monkeys (and their neurons) are calculating statisticians

Using a simple psychological test, scientists showed that monkeys can use simple statistical calculations to make decisions and even managed to catch individual neurons in the act of computing.

30) ‘Brainbow’ paints individual neurons with different colours

Monkeys weren’t the only ones to have their neurons watched. One group of scientists developed a technique that paints the neurons of mice with over 90 colours using a palette of fluorescent proteins. This ‘Brainbow’ provides an unprecedented view of the connections in our brains.

Geology

31) Megaflood in English Channel separated Britain from France

Just in time for the major summer floods in England, a group of scientists found that a megaflood broke through a land bridge that connected England to France, created the English Channel and separated Britain from the rest of Europe.

32) How India became the fastest continent

Continents may move slowly but among them, India is the champion sprinter. When it broke off from the supercontinent Gondwana, a plume of molten rock melted away India’s large rocky roots, turning it into a free-floating raft among strongly anchored peers.