The brain devotes more processing resources to social situations that signal threat than those that are benign and anxious people process those threats using regions of the brain responsible for action, says a study.
The study that may help explain the apparent "sixth sense" we have for danger found that "low anxious" people process the threats in sensory circuits, responsible for face recognition.
It was previously thought that anxiety could lead to oversensitivity to threat signals. However, the new study showed that the difference has a useful purpose.
Non-clinical anxiety shifts the neural 'coding' of threat to motor circuits, which produce action, from sensory circuits, which help us to recognise faces, the researchers explained.
Facial displays of emotion can be ambiguous but the researchers managed to identify what it is that makes a person particularly threatening.
They found that the direction a person is looking in is key to enhancing our sensitivity to their emotions.
More From This Section
Anger paired with a direct gaze produces a response in the brain in only 200 milliseconds, faster than if the angry person is looking elsewhere.
"In a crowd, you will be most sensitive to an angry face looking towards you, and will be less alert to an angry person looking somewhere else," said lead author Marwa El Zein from the French Institute of Health and Medical Research (INSERM).
Similarly, if a person displays fear and looks in a particular direction you will detect this more rapidly than positive emotions. Such quick reactions could have served an adaptive purpose for survival.
For the study, electrical signals measured in the brains of 24 volunteers were analysed while they were asked to decide whether digitally altered faces expressed anger or fear.
"In contrast to previous work, our findings demonstrate that the brain devotes more processing resources to negative emotions that signal threat, rather than to any display of negative emotion," El Zein noted.
The study appeared in the journal eLife.