Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Impulsive behavior may be relict of hunter-gatherer past

07.12.2004


Drawing on experiments with blue jays, a team of University of Minnesota researchers has found what may be the evolutionary basis for impulsive behavior. Such behavior may have evolved because in the wild, snatching up small rewards like food morsels rather than waiting for something bigger and better to come along can lead to getting more rewards in the long run. The work may help explain why many modern-day humans find it so hard to turn down an immediate reward--for example, food, money, sex or euphoria--rather than investing and waiting for a bigger reward later. The work will be published in the Dec. 7 issue of the Proceedings of the Royal Society (London).



In experiments with blue jays, David Stephens, a professor of ecology, evolution and behavior in the university’s College of Biological Sciences, found that birds presented with a choice of getting a small food reward immediately or waiting a short time for a bigger one could not be trained to wait, even after a thousand repetitions. Many researchers have explained such impulsiveness as the result of the bird "discounting" the value of a delayed reward--that is, instinctively realizing that a reward delayed may be a reward denied because conditions can change while the bird is waiting. But the birds’ impulsiveness was simply too strong to explain that way, Stephens said.

"I think we were asking them the wrong question," he explained. "In nature, they don’t often encounter a situation where they must give up a better, but delayed, food morsel when they grab a quick meal. So we designed an experiment that better modeled real life in the wild."


The new experiments were modeled on how animals encounter and exploit food clumps. The jays encountered one clump at a time and obtained some food from it. Then they had to decide whether to wait for a bit more from the same clump or leave and search for another clump. Not surprisingly, the birds still acted impulsively, preferring items they could get quickly. They considered only the size and wait time for their next reward--never a reward beyond that, even though it may have been bigger.

What did surprise Stephens was that the birds that went for the immediate reward were able to "earn" as much or more food in the long run as birds that were forced to wait for the larger reward or to follow a mixed strategy. The reason, he said, was that in the wild, animals aren’t faced with an either-or choice of "small reward now or big reward later." What happens is that when they find a small bit of food, they don’t wait; they just go back to foraging, and they may find lots of little rewards that add up to more than what they would get if they had to hang around waiting for bigger and better.

"Animals, I think, come with a hardwired rule that says, ’Don’t look too far in the future,’" Stephens said. "Being impulsive works really well because after grabbing the food, they can forget it and go back to their original foraging behavior. That behavior can achieve high long-term gains even if it’s impulsive."

The work may apply to humans, he said, because taking rewards without hesitation may have paid off for our foraging ancestors, as it does for blue jays and other foragers. Modern society forces us to make either-or decisions about delayed benefits such as education, investment and marriage; the impulsive rules that work well for foragers do more harm than good when applied in these situations.

"Impulsiveness is considered a big behavior problem for humans," said Stephens. "Some humans do better at binary decisions like ’a little now or a lot later’ than others. When psychologists study kids who are good at waiting for a reward, they find those kids generallly do better in life. It looks as though this is a key to success in the modern world, so why is it so hard for us to accept delays? The answer may be because we evolved as foragers who encountered no penalties for taking resources impulsively.

"Also," Stephens added, "the National Institute on Drug Abuse funds a lot of studies of impulsiveness. It seems to play a part in addiction. I think anything we can do to understand impulsivity is a plus."

Deane Morrison | EurekAlert!
Further information:
http://www.umn.edu

More articles from Ecology, The Environment and Conservation:

nachricht Safeguarding sustainability through forest certification mapping
27.06.2017 | International Institute for Applied Systems Analysis (IIASA)

nachricht Dune ecosystem modelling
26.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Physicists Design Ultrafocused Pulses

Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.

Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

Programming cells with computer-like logic

27.07.2017 | Life Sciences

Identified the component that allows a lethal bacteria to spread resistance to antibiotics

27.07.2017 | Life Sciences

Malaria Already Endemic in the Mediterranean by the Roman Period

27.07.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>