US researchers point out exact areas in the brain responsible for emotional spillover

An electroencephalography (EEG) cap which measures brain activity. Image: Reuters/Michaela Rehle

As part of efforts to understand the emotional side of the brain, researchers in the US have for the first time pinpointed areas directly responsible for emotional spillover.

When we let emotions from one event carry on to the next, such spillover can colour our impressions and behaviour in those new situations – sometimes for the worse.

Using Transcranial Magnetic Stimulation (TMS), a technique that can temporarily “knock out” or inhibit activity in specific parts of the brain, the team discovered that when the lateral prefrontal area of the brain (a region known for executive function) was inhibited by the stimulation, participants showed more emotional spillover.

For the experiment, the team from the Center for Healthy Minds at the University of Wisconsin-Madison collected people’s ratings and first impressions of neutral faces they saw immediately after faces that were smiling, prompting positive emotions, or fearful, prompting negative emotions.

“It was interesting because participants saw the emotional faces very briefly and when asked afterward, they didn’t think that they had been influenced by it in their ratings,” said Regina Lapate who led the work.

“Emotional spillover can happen without us being aware of it,” Lapate added in the study published in the journal of the Association for Psychological Science.

“If your first impression of someone is formed when you’re experiencing emotional spillover from a previous context, that negative impression may stick,” Lapate said.

Next on Lapate’s agenda is to test whether the reverse works, i.e. can TMS stimulation that increases neural firing in the prefrontal cortex lead to a decrease in negative emotional spillover.