New research suggests that confidence, what some people assume is an innate character trait that fluctuates depending on the gravity of a given situation, may actually exist as a "measurable quantity," reports the Cold Spring Harbor Laboratory. That's the case with rats anyway - and probably with humans too, notes the research team.

Scientists arrived at their findings using rats and identifying the brain regions that figure in their decision making. The rats were offered an odor that they were trained to associate with one of two doors - the so-called "correct door" that has an edible reward. For part two of the test, the researchers confused the rats by presenting them with a mix of the two scents, making sure the "correct" scent was just slightly more detectable than the incorrect scent. The rats were then tasked with taking their best guess. Was the treat behind door number one or door number two? The research team was able to measure rodent confidence levels by observing how long each rat was willing to wait before it made its decision in search of a reward. Sometimes the rats would wait as long as 15 seconds, an unusually long length of time for rodents, but one that indicated that a thinking process had taken place before the rat darted in through his selection.  

"We found that rats are willing to 'gamble' with their time," CSHL Associate Professor Adam Kepecs said. "The time rats are willing to wait predicts the likelihood of correct decisions and provides an objective measure to track the feeling of confidence."

The team hypothesized that a distinct part of the brain might control confidence - possibly the orbitofrontal cortex (OFC), which is involved in making predictions. And true to form, after researchers specifically shut off neurons in the OFC of test rats, they found that the normally confident rodents were significantly less so when it came to being confronted with a test involving decision making.

"With an inactive OFC, the rats retained the ability to make decisions – their accuracy did not change," Kepecs said. "And they spent the same amount of time waiting for a reward on average. The only difference is that animals' willingness to wait for a reward was no longer guided by confidence. They would often wait a long time even when they were wrong."

The findings could help researchers gain insight in the levels of confidence humans possess as well as how such levels impact decision making.  

 "We now know that the OFC is critical for making on-the-fly predictions in rats. The human OFC is just a more sophisticated version of the rodent counterpart," Kepecs said.

The study's findings were published Sept. 18 edition of the journal Neuron.