Concept of time may predict impulsive behavior, research finds

"Our research suggests that individuals with greater self-control have a better understanding of delays, which means that they can wait for a longer period of time to earn a larger reward," said Kimberly Kirkpatrick, professor of psychological sciences. "For example, we know that preparing a meal at home is a healthier option than fast food. However, impulsive people are more likely to eat fast food instead of preparing a meal. It may not be because they don't understand the health benefits, but rather that they lack delay tolerance, leading to the impulsive decision of opting for fast food."

Kirkpatrick; Aaron Smith, department of psychology at the University of Kentucky; and Andrew Marshall, doctoral student in psychology at Kansas State University, published "Mechanisms of Impulsive Choice: I. Individual Differences in Interval Timing and Reward Processing" in the Journal of the Experimental Analysis of Behavior.

The researchers studied rats to determine if particular factors affect individual choices, particularly looking at how long rats can wait to earn a larger reward. Rats were given two different levers to push. One lever produced a small treat after a short time, the other lever produced a larger treat that required waiting longer -- a scenario Kirkpatrick said was common for humans.

"We don't often know the outcome of a situation until we have experienced it," she said. "For example, we find out what restaurants have faster service than others and we use that information to make our decision about where to eat in the future."

The researchers determined delay tolerance through progressive intervals. Researchers methodically increased the amount of time before distributing rewards. The rats that could endure longer time intervals before getting food had more self-control and also were better at timing the intervals. The impulsive rats showed poor timing abilities and were more intolerant of the delays.

"The impulsive rats didn't have the ability to wait for a reward because they didn't understand time," Kirkpatrick said. "We consider decision-making a malleable trait and believe it can be improved through intensive training. Improving the concept of time could help those vulnerable to impulsive behaviors."

The researchers' findings about why certain individuals are more impulsive than others could lead to behavioral interventions instead of the use of medication for clinical disorders, said Kirkpatrick. She hopes to develop alternative treatment methods for impulsive behaviors through behavioral interventions designed to improve the individual's understanding of time.