Washington: Man and his best friend dog have something in common -- both behave aggressively when they run out of self-control, scientists say.
Researchers at the University of Lille Nord de France found that dogs that have "run out" of self-control make more impulsive decisions that put them in danger.
The study, published in the journal Psychonomic Bulletin & Review, reinforces the biological nature of self-control, said lead study researcher Holly Miller.
"When humans are depleted, they are less helpful, more aggressive, gamble more, etc.," Miller told LiveScience.
"Well apparently these consequences also have biological roots. When dogs are depleted, they too are more likely to behave rashly and impulsively."
Miller and her colleagues had previously found that dogs give up sooner on a puzzle-solving task after they've had to hold a sit-stay position than if they didn't have to exhibit
any self-control. In the same way, humans give up more quickly on puzzle tasks when they're mentally fatigued by having to resist temptations beforehand.
In the study, the researchers carried out experiments on 10 family-owned dogs in the lab. In one session, the dog was told to sit and stay on a mat while a distracting toy hamster
roamed around the floor. In another trial, the dog was caged for 10 minutes so that it didn't have to exert self-control.
After the sit-stay session, the dog was brought into a room that held a cage with an 11-year-old female bull terrier that snarled and barked when it saw the second dog.
It was found that dogs spent 58.9 per cent of their time in the portion of the room closest to the angry dog's cage after the sit-stay session, compared with only 41.8 per cent of time they spent after relaxing in a cage for 10 minutes.
According to Miller, the results are important for humans and dogs alike. People should realise that their tendency to make dumb decisions when tired is not a sign of personal failure and that it can be overcome with willpower, she said.
"We tend to believe we should have some superhuman power to avoid these things. We don't. What we do have the ability to do is to plan ahead. To recognise our weaknesses, and to prevent ourselves from having the opportunity to behave in ways that are not optimal for our lives," Miller said.
For example, in both dogs and humans, a sugary drink seems to provide the brain with the fuel it needs to harness our silliest impulses. A dieter, then, might take care not to
avoid food too assiduously, given that a small snack could boost the willpower needed to avoid a big food splurge.
Dog owners should take note, too, Miller said.
A family dog that has to restrain its urge to snap at yelling, screaming kids all day may eventually reach a willpower limit and bite, possibly explaining a large proportion of the 4.5 million dog bites in America each year.
It's up to people to recognise that dogs need breaks and rest as much as we do, she said.
First Published: Thursday, April 05, 2012, 12:33