Very few people can solve the nine-dot puzzle on first attempt. The simple-sounding task is to draw four straight lines connecting all nine dots, see the illustration right, without removing pen from paper or retracing.
When researchers from Sydney recently asked 22 people to try, not surprisingly none of them succeeded. But when a mild electric current was applied for 10 minutes to the brains of 11 of the volunteers, five of them worked it out. The 11 in the control group, who received a sham dose of current, were left in the dark.
The study, published last month in Neuroscience Letters by scientists at the University of Sydney's Centre for the Mind, is part of an international bid to understand how to enhance our thinking - to improve learning, memory, attention, alertness and insight.
Known as transcranial direct current stimulation, this electrical technique is in its infancy. But it has captured the interest of the armed forces, with a recent study in the US showing it could double the performance of
people trained to identify hidden targets using a virtual reality environment.
Along with other brain imaging techniques, ''it may prove to be the much sought-after tool to enhance learning in a military context'', a report on neuroscience by the Royal Society in Britain concluded in February.
From amphetamines that kept soldiers alert during the Vietnam War to today's use of a newer drug to help pilots combat fatigue, the military has long embraced mind-altering drugs as a weapon of war.
But soldiers are no longer a special case. Some academics, university students, doctors and shift workers report buying prescription drugs such as methylphenidate (Ritalin) and modafinil (Provigil) in a bid to get higher grades and boost performance.
A survey of Australian university students showed most regard taking drugs like Ritalin to cram for exams as cheating and unethical. But the development and use of techniques to boost brain power has the support of some bioethicists who argue society must respond to a growing demand for brain power aids.
''Cognitive enhancement has much to offer individuals and society,'' Professor Henry Greely, of Stanford Law School, says.
He and his colleagues argue that drugs, brain stimulation and brain chips should be regarded as similar to education, getting a good night's sleep or the internet - ''ways that our uniquely innovative species tries to improve itself''.
Everyone's memory deteriorates after the age of 40, so ''enhancement is an issue of vital concern to all of us'', says Australian ethicist, Professor Julian Savulescu, of Oxford University. In a new book he has co-edited, Enhancing Human Capacities, he argues that improvements in memory, attention and mood - through pharmaceutical, genetic or other high-tech means - could bring significant social and economic benefits for individuals.
They should be supported if they increase a person's chance of leading a good life. ''As technology advances, parents will have a duty to enhance their children,'' Professor Savulescu predicts.
Chris Gyngell, a PhD student at the Australian National University, says this argument that cognitive enhancement would let people lead better, happier lives is persuasive. But he says the impact on society, not just the individual, also needs to be taken into account. For example, parents may want to give their children a drug that makes them attentive in class so they can learn better but this may inadvertently reduce creativity, which is needed for an innovative society, he says.
Many people simply dismiss the issue because they think all drugs are bad. But it is likely that some that can safely boost mental capacities in healthy people will eventually become available, and society needs to consider the implications now, says Dr Olivia Carter, of the University of Melbourne. ''If these drugs are shown to be helpful there is going to be a market,'' she said.
Carter cautions that such drugs ''may affect the very essence of who we are as people''. As well, there will inevitably be problems with equal access to any smart pills and possible coercion to use them.
Researchers at the University of Queensland Centre for Clinical Research are keen to ''deflate the neuroenhancement bubble'', claiming the debate is flawed by hype and a lack of historical perspective.
A team member, Associate Professor Jayne Lucke, says claims of widespread off-label use of these drugs by university students and others are exaggerations and evidence for any real benefits in healthy people is much weaker than enthusiasts suggest. Bioethicists who want to relax regulations for drugs now available have also underestimated the difficulties in assessing their safety and efficacy in healthy people, she says.
Surveys of US college students suggest about 7 per cent have popped stimulant drugs such as Ritalin to help them study, although fewer - only about 2 per cent - reported use in the previous month.
Lucke says a survey of German students last year showed less than 1 per cent had used drugs for cognitive enhancement, and ''there is limited data available from other countries, including Australia''.
To gauge attitudes here, the University of Queensland team interviewed 19 university students, aged from 18 to 31. Most said cognitive enhancement amounted to cheating. They didn't want it banned nor promoted at university, but said there should be education about the risks and monitoring of patterns of use.
Carter says the drugs already available raise many important ethical issues beyond the health concerns because of a lack of research.
For example, studies have shown that propranolol can erase people's fearful memories of spiders, which suggests it may be able to treat post-traumatic stress disorder. ''But might we be fundamentally changing our identities or sense of self if we tamper with the emotional content of our memories?'' she asked.
Being able to reduce the fearful memories of victims of a crime could also reduce their right for compensation, or reduce the incentive to punish perpetrators, she says.
And if a drug like modafinil is available to keep people alert during long shifts, will everyone be expected to take it so they can work more hours?
A drug to boost concentration and memory may sound like a good thing but how would it feel if a competitor at work was taking it? And might parents see it as no different, ethically, to employing a tutor for their child?
Gyngell says the trust-inducing drug oxytocin could have negative consequences for society if lots of people want to be ''loved up'' on it, and let down their guard.
Greely and his colleagues sparked the enhancement debate with an influential paper in the journal Nature three years ago, promoting cognitive enhancement for mentally competent adults as long as there is ''appropriate research and evolving regulation''.
Taking drugs requires little effort, is invasive and not everyone can afford it. ''But none of these provides reasonable grounds for prohibition,'' they said.
Lucke and her colleagues, including Stephanie Bell, and Professor Wayne Hall, however, argue bioethicists in favour of enhancement should not unwittingly encourage the use of drugs such as Ritalin in the absence of good evidence of their safety and benefits.
Present enthusiasm is reminiscent of similar claims made for cocaine in the later 19th and early 20th centuries and for amphetamines in the mid 20th century, they point out in recent scientific articles in journals including AJOB Neuroscience.
''They were seen as safe and effective wonder drugs that increased alertness and mental capabilities,'' Lucke says.
An initial steep rise in medical prescriptions was followed by an increase in recreational use, fuelled by uncritical enthusiasm for the drugs' benefits. Then unwanted side effects such as addiction became apparent and they were eventually banned.
''It is important that we avoid repeating this experience,'' she says.