New research suggests that these two types of people, have different ways of addressing the tasks to be performed: The worker thinks more efficient in the final award, while the lazy focuses more attention on the effort.

However, research that was conducted in rats, also reveals an unexpected factor: The stimulants such as amphetamines appear to switch roles. "Workers choose efficient and easier tests chosen toughest vague", according to researcher Jay Hosking, a graduate student at the University of British Columbia.

Caffeine makes lazy workers in rats, but, unlike amphetamines, does not transform the productive lazy superstars. Study results were published on 28 March in the journal Neuropsychopharmacology.

Hosking and his colleagues trained and assessed the motivation of 20 rats. Put them in boxes with two levers and five holes. During task, one of the holes is lighted. By entering your nose in the hole, the rat received a gift in the form of sugar pellets. Using the lever, the rats could choose between a difficult task, in which the hole is illuminated a fifth of a second - what it takes to blink - and an easier, in which the hole is lit for a full second.

"Even in the world of rats and pigeon peas are workers," says Hosking. "As in humans, there are different levels of activity."

If completed successfully the difficult task, requiring more effort, they received double the sugar granules when they made the task easy. These tasks, according to Hosking, the equivalent would do the bare minimum at work or go beyond the hope of a promotion.

As in humans, rats frequently chose the simplest tasks and others, however, chose the hardest task where the reward was greater.

When given stimulants, caffeine or amphetamines, became more impulsive, acted faster but still accurate when sniffing the hole illuminated. However, the two personalities of the rat had opposite reactions when choosing between jobs.

With either drug, the rats became lazy workers, preferring the easy tasks. Meanwhile, the rats "loungers" to which was given amphetamines, behaved as an efficient worker. Interestingly, caffeine did not produce the same effect.

"The good news is that caffeine does not do worse than rats lazy, but it certainly reduces the willingness of good people for hard work," said Hosking.

Why is there this difference between the two stimulants? "Both are stimulating and exciting, but have different specific effects on the brain"

The results could explain why amphetamine-type stimulants like Adderall help calm who has attention deficit hyperactivity disorder (ADHD). Perhaps the drug helps people make in workers concentrated distracted.