Indian scientists have discovered that uncertainty about near-future events is a key driver of human emotions, bolstering evidence that challenges longstanding notions that confined the human emotional spectrum to six basic types.
Their study provides novel insights into the brain mechanisms of emotions and may explain everyday phenomena such as why the wait for exam results can be an ordeal, or why spoilers that eliminate surprise or suspense in a book or movie plot can be so frustrating.
Scientists at the National Brain Research Centre (NBRC) in Manesar, Haryana, probed emotions using the so-called functional magnetic resonance imaging (fMRI) brain scans data from 110 volunteers as they watched segments from Bang! You’re Dead, a 1961 TV episode of Alfred Hitchcock Presents directed by Alfred Hitchcock (not the 1954 British movie by the same name.)
The segments featured several situations marked by high uncertainty, each of which left the viewers wondering for a few seconds whether a seven-year-old boy might unknowingly pull the trigger of a partially loaded gun, pointed at a different person each time.
“The greater the uncertainty, the more intense the emotion,” said Dipanjan Roy, a scientist at the NBRC, who led the study.
Neuro scientists had for decades assumed that human emotions could be described through six basic emotional states — happiness, sadness, anger, surprise, fear and disgust — and their different levels of intensity, from high to low.But since 2016, studies have hinted that these six states are not sufficient to describe the spectrum of emotions humans can display.
A 2021 study by US and Chinese scientists, for instance, found that brain activity patterns of fear generated in the lab were different from those arising out of fear from real threats.The NBRC study is the first to show that the brain region called the lateral orbitofrontal cortex (LOFC), located above the eyes — and earlier linked to decision-making and reward tasks — is also a key brain region for processing emotions related to uncertainty.In the study, peaks in the LOFC activity coincided with moments in the movie when viewers were uncertain whether the boy would pull the trigger.
As the uncertainty vanished and the viewers learnt the outcome, the LOFC activity fell.The scientists say their findings may help explain the emotional toll extracted by uncertainty in some everyday situations, as well as the peaking of emotions during the climax or a twist in a book or a movie.
The findings were published last week in the journal Cerebral Cortex.Gargi Majumdar, a research scholar at the NBRC and a study team member, said: “The wait for an exam result or a medical test result can be emotionally draining because of the high uncertainty about the possible outcomes.”Majumdar said the uncertainty-emotions link also explains the distaste for spoilers. “The climax or the twist holds the maximum uncertainty. If I already know what’s going to happen, I’ll be bored instead of being excited by what is to come,” Majumdar said.The NBRC researchers set out to analyse brain activity as emotions changed with time, relying on the fMRI data — generated earlier by the Cambridge Centre for Ageing and Neuroscience in the UK — of viewers watching the movie segment.They found that the LOFC was at the top of a hierarchy of areas — in the brain region called the prefrontal cortex — that were activated the most during moments of the greatest uncertainty in the movie.“As people experienced emotional ups and downs while watching the segments, the LOFC tracked the changes continuously in a consistent manner, modulating its activity upward and downward,” said Fahd Yazin, a study team member now at the University of Edinburgh.
“The analysis has suggested that the LOFC activity patterns also reflect people’s default or baseline anxiety levels.”The scientists say their results could lead to an enhanced understanding of the mechanisms underlying certain mental health disorders, including obsessive-compulsive disorder, anxiety disorder and post-traumatic stress disorder.“Such conditions have been hard to characterise because of the broad spectrum of behaviours,” Roy, an associate professor with the Centre for Brain Science at the Indian Institute of Technology, Jodhpur, said.
“But our findings suggest that such disorders could be studied through the angle of mis-estimation of uncertainty. And the LOFC activity could be used to predict anxiety scores.”Scientists not associated with the NBRC study said it had generated fresh evidence for the idea that human emotions are far more complex than assumed earlier through the six basic states and the high-low intensity ascribed to each.“This study is consistent with others that suggested close relationships between decision-making and emotional processes, and the encoding of emotional information in the LOFC, which is also involved in decision-making,” said Pragathi Balasubramani, an assistant professor at the cognitive science centre at IIT Kanpur.Another neuro scientist, Arjun Ramakrishnan, an assistant professor of biological sciences and bio engineering at IIT Kanpur, said the NBRC study had uncovered the effects of uncertainty on emotions and disentangled the LOFC’s role in this process.
