In a surprising new study, researchers have discovered that the activity of individual nerve cells in the brain reveals the amount of confidence we have as we make decisions. The experts found that the firing rate of certain brain cells increased when individuals felt the most confident in their choices.
The researchers monitored the activity of 830 different nerve cells located in the temporal lobe as volunteers chose between various foods. Study co-author Dr. Florian Mormann is a professor in the Department of Epileptology at the University of Bonn.
“We showed them photos of two different snacks, for example a chocolate bar and a bag of chips,” said Dr. Mormann. “They were then asked to use a slider to indicate which of these alternatives they would rather eat.”
The farther the slider was moved to the left or right from its center position, the more confident a volunteer was in his or her decision. Overall, the participants judged 190 different snack pairs.
“We discovered that the frequency of the electrical pulses in some neurons, in other words their ‘firing rate’, changed with increasing decision confidence,” explained study co-author Alexander Unruh-Pinheiro. “For instance, some fired more frequently, the more confident the respective test person was in their decision.”
The study is the first to identify a correlation between brain cell activity and decision confidence. The experts noted that these particular nerve cells are located in a region of the brain involved in memory processing.
“It is possible that we not only store what decision we made, but also how confident we were in it,” said Dr. Mormann. “Perhaps such a learning process saves us from future wrong decisions.”
The research was initially designed to investigate an entirely different brain process that takes place during decision-making: when we make a selection, we assign a subjective value to each of the rejected options.
“There is evidence that this subjective value is also reflected in the activity of individual neurons,” said Dr. Mormann. “The fact that we instead came across this connection between fire behavior and decision confidence surprised even us.”
The study is published in the journal Current Biology.