Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fast eye movements: A possible indicator of more impulsive decision-making

22.01.2014
Using a simple study of eye movements, Johns Hopkins scientists report evidence that people who are less patient tend to move their eyes with greater speed.

The findings, the researchers say, suggest that the weight people give to the passage of time may be a trait consistently used throughout their brains, affecting the speed with which they make movements, as well as the way they make certain decisions.

In a summary of the research to be published Jan. 21 in The Journal of Neuroscience, the investigators note that a better understanding of how the human brain evaluates time when making decisions might also shed light on why malfunctions in certain areas of the brain make decision-making harder for those with neurological disorders like schizophrenia, or for those who have experienced brain injuries.

Principal investigator Reza Shadmehr, Ph.D., professor of biomedical engineering and neuroscience at The Johns Hopkins University, and his team set out to understand why some people are willing to wait and others aren't. "When I go to the pharmacy and see a long line, how do I decide how long I'm willing to stand there?" he asks. "Are those who walk away and never enter the line also the ones who tend to talk fast and walk fast, perhaps because of the way they value time in relation to rewards?"

To address the question, the Shadmehr team used very simple eye movements, known as saccades, to stand in for other bodily movements. Saccades are the motions that our eyes make as we focus on one thing and then another. "They are probably the fastest movements of the body," says Shadmehr. "They occur in just milliseconds." Human saccades are fastest when we are teenagers and slow down as we age, he adds.

In earlier work, using a mathematical theory, Shadmehr and colleagues had shown that, in principle, the speed at which people move could be a reflection of the way the brain calculates the passage of time to reduce the value of a reward. In the current study, the team wanted to test the idea that differences in how subjects moved were a reflection of differences in how they evaluated time and reward.

For the study, the team first asked healthy volunteers to look at a screen upon which dots would appear one at a time ¬–– first on one side of the screen, then on the other, then back again. A camera recorded their saccades as they looked from one dot to the other. The researchers found a lot of variability in saccade speed among individuals but very little variation within individuals, even when tested at different times and on different days. Shadmehr and his team concluded that saccade speed appears to be an attribute that varies from person to person. "Some people simply make fast saccades," he says.

To determine whether saccade speed correlated with decision-making and impulsivity, the volunteers were told to watch the screen again. This time, they were given visual commands to look to the right or to the left. When they responded incorrectly, a buzzer sounded.

After becoming accustomed to that part of the test, they were forewarned that during the following round of testing, if they followed the command right away, they would be wrong 25 percent of the time. In those instances, after an undetermined amount of time, the first command would be replaced by a second command to look in the opposite direction.

To pinpoint exactly how long each volunteer was willing to wait to improve his or her accuracy on that phase of the test, the researchers modified the length of time between the two commands based on a volunteer's previous decision. For example, if a volunteer chose to wait until the second command, the researchers increased the time they had to wait each consecutive time until they determined the maximum time the volunteer was willing to wait — only 1.5 seconds for the most patient volunteer. If a volunteer chose to act immediately, the researchers decreased the wait time to find the minimum time the volunteer was willing to wait to improve his or her accuracy.

When the speed of the volunteers' saccades was compared to their impulsivity during the patience test, there was a strong correlation. "It seems that people who make quick movements, at least eye movements, tend to be less willing to wait," says Shadmehr. "Our hypothesis is that there may be a fundamental link between the way the nervous system evaluates time and reward in controlling movements and in making decisions. After all, the decision to move is motivated by a desire to improve one's situation, which is a strong motivating factor in more complex decision-making, too."

The other authors of the report are Jennie Choi and Pavan Vaswani of the Johns Hopkins University School of Medicine.

This work was supported by grants from the National Institute of Neurological Disorders and Stroke (NS078311) and the Human Frontier Science Program.

On the Web:

Link to article: http://dx.doi.org/10.1523/jneurosci.2798-13.2013

Shadmehr Lab: http://www.bme.jhu.edu/people/primary.php?id=396

Catherine Kolf | EurekAlert!
Further information:
http://www.jhmi.edu

More articles from Studies and Analyses:

nachricht The Great Unknown: Risk-Taking Behavior in Adolescents
19.01.2017 | Max-Planck-Institut für Bildungsforschung

nachricht A sudden drop in outdoor temperature increases the risk of respiratory infections
11.01.2017 | University of Gothenburg

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Scientists spin artificial silk from whey protein

X-ray study throws light on key process for production

A Swedish-German team of researchers has cleared up a key process for the artificial production of silk. With the help of the intense X-rays from DESY's...

Im Focus: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Breaking the optical bandwidth record of stable pulsed lasers

24.01.2017 | Physics and Astronomy

Choreographing the microRNA-target dance

24.01.2017 | Life Sciences

Spanish scientists create a 3-D bioprinter to print human skin

24.01.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>