How Mixed Emotions Are Represented in the Brain

Countless parents around the country have recently taken their children to university for the first time.

The change can unleash a swirl of emotions: pain at saying goodbye, sadness that family life has altered forever, and uncertainty about what comes next – alongside pride in watching a child take steps towards independence.

Many would call the farewell bittersweet, or say they are experiencing mixed emotions.

In this situation, how would you respond if asked to score your feelings from 1-9, where 1 is the most negative and 9 is the most positive? The question may appear absurd in these circumstances – how can a combination of good and bad feelings be rated?

Nevertheless, psychology researchers frequently use precisely this scale to assess emotions in scientific studies, classifying feelings as positive or negative, but not both at once.

As a neuroscientist researching how the brain represents mixed emotions, I ask whether people genuinely experience positive and negative feelings simultaneously. Or are they simply moving rapidly between the two?

What emotions do for you

Scientists sometimes describe emotions as brain-and-body states that drive you either towards things or away from them. Generally, people experience these states as positive or negative.

Imagine you are walking through woodland and spot a bear. Your heart rate rises and your breathing speeds up, creating an urge to run – which may help you choose an action that keeps you alive. Many scientists would identify this response as the emotion of "fear."

Likewise, affectionate feelings towards people you love encourage you to remain close to them and care for those relationships, strengthening your social network and support system.

This model of emotions as approach and avoidance helps account for why they evolved and how they shape decision-making. It has also served as a central principle for scientists investigating the biology of emotion.

Mixed emotions, however, sit uneasily within this model. If opposing biological systems suppress one another, and emotions are biological, then opposites cannot be experienced in the same instant.

Following this logic, holding two opposing emotions at once would be impossible; instead, you would have to switch between them. Since scientists first developed theories about the biological basis of emotion, this has been their way of understanding mixed emotions.

Untangling the biology of mixed emotions

The standard ways of measuring feelings still place positive and negative emotions at opposing ends of one spectrum. Yet participants in research studies routinely say they experience mixed emotions.

For example, people from different cultures describe certain feelings, including nostalgia and awe, as both positive and negative at the same time.

One research team found that volunteers’ physiological reactions – including heart rate and skin conductance – followed distinctive patterns when an experience was simultaneously disgusting and funny, compared with either experience on its own.

This suggests that disgust and amusement are truly happening together to produce something new.

In an apparently conflicting result, research using functional magnetic resonance imaging, or fMRI, to examine brain responses to disgusting humour did not identify a brain-activity pattern distinct from ordinary disgust.

The brain states of people who said they felt disgusted and amused appeared to show disgust alone – rather than a separate pattern for a novel mixed emotion.

However, fMRI research usually depends on averaging brain activity across both time and participants. The key issue – whether people are genuinely experiencing mixed emotions or fluctuating between positive and negative states – is about what the brain does through time.

By averaging activity over time, scientists may produce a pattern that closely resembles a single emotion – disgust, in this example – while overlooking crucial details about whether activity shifts or remains stable from second to second.

Mixed emotions in the brain

To investigate this possibility, I conducted a study examining whether mixed emotions were linked to a distinctive brain state that remained stable over time.

Inside an MRI scanner, participants watched a bittersweet animated short film about a young girl’s lifelong ambition to become an astronaut, supported by her father.

Spoiler alert: Her father dies. Once the scanning was complete, the same participants watched the video again and marked the precise moments when they had felt positive, negative and mixed emotions.

My colleagues and I found that mixed emotions did not produce distinct, stable patterns in deeper brain regions such as the amygdala, which is central to rapid responses to emotionally significant things.

Notably, the insular cortex – a brain area connecting deeper regions with the cortex – showed stable, distinctive patterns for positive and negative emotions alike, but not for mixed emotions.

We interpreted this result as meaning that regions including the amygdala and insular cortex process positive and negative emotions as mutually exclusive.

Yet we did observe distinctive, stable patterns in cortical areas including the anterior cingulate, which is important for processing conflict and uncertainty, and the ventromedial prefrontal cortex, which matters for self-regulation and complex thought.

These cortical brain regions, which perform more sophisticated functions, seem able to represent far more complex states, enabling a person to genuinely experience a mixed emotion.

Areas such as the anterior cingulate and ventromedial prefrontal cortex combine many information sources – a capability essential to forming a mixed emotion.

Our results also align with scientific knowledge of emotional and brain development. Notably, children only start to recognise or report mixed emotions later in childhood.

That timing corresponds with researchers’ understanding that the development of these brain regions brings more advanced emotional understanding and regulation.

What happens next

This study uncovered something new about the brain’s formation of complex feelings, although much remains to be discovered.

Mixed emotions are especially intriguing because they may play a part in significant life events. At times, they help people manage major changes and become treasured memories.

For instance, you might feel both positive and negative emotions when friends hold a large leaving party before you relocate to another city for your dream job.

At other times, mixed emotions become a continuing source of distress. Knowing that you ought to end a relationship with a romantic partner does not mean your positive feelings for them disappear automatically, nor does it mean that separation will not hurt.

What creates this difference in outcomes? Could it be connected to how the brain represents these mixed emotional states over time?

A stronger understanding of mixed emotions could help people ensure that powerful feelings become cherished memories that support personal growth, rather than a painful farewell they cannot move beyond.

Anthony Gianni Vaccaro, Postdoctoral Research Associate in Psychology, USC Dornsife College of Letters, Arts and Sciences

This article is republished from The Conversation under a Creative Commons licence. Read the original article.