Feeling anxious is pretty stressful already, so not being able to read the emotions of other people around you, especially if they are trying to offer some kind of help or empathy, just makes everything harder.

A new study published in Royal Society Open Science has revealed that when people are in a state of anxiety, they find it harder to read the emotional expressions of people, more often than not identifying anger rather than happiness in people's faces when in this state.

The researchers set out to build on previous research that showed people with “trait anxiety”, a tendency towards anxiety, struggle with emotional face processing. However, they wanted to look specifically at “state anxiety”, the emotional response to the threat of danger, and how that affects their recognition of emotional expressions.

“We were specifically trying to answer the question: how does our current level of anxiety influence how we see the world, and in particular emotions in faces?” co-author Marcus Munafò of the University of Bristol told the Guardian.

Emotional face processing is a fundamental part of social interaction, allowing us to not only communicate non-verbally our thoughts, feelings, emotions, and intentions, but to understand these things about the people we are interacting with. It can dictate how we behave towards other people and even whether we avoid them completely.  

To study the impact of an anxiety-inducing situation on one's ability to interpret facial expressions, they gave 21 healthy participants a face mask that fed them either normal air or carbon dioxide-enriched air – known to raise the heart rate and blood pressure and induce stress.

They then showed the participants 15 images of a man’s face with various emotions – anger, disgust, fear, sadness, surprise, and happiness – and asked them to assign each image one of the emotions.

Next, they were shown 45 images showing 15 different people expressing an emotion somewhere between happiness and anger and asked to identify the emotion in each photo. Both experiments were repeated on the 21 original participants and a further 40 people.

Finally, an online questionnaire that involved 1,994 people repeated the first part of the study that assigned six emotions to the 15 photos of a man's face, while self-reporting on their current state of anxiety. 

They found that people were 8 percent worse at identifying facial expressions correctly when they had experienced the anxiety-inducing carbon dioxide air. They also found that the anxious group were more likely to associate facial expressions ranging between anger and happiness as angry, though they did find this association was less in the larger group.

The researchers concluded that a higher state of anxiety resulted in poorer emotional recognition, though further study to replicate the results is needed for more concrete proof.