Affiliations : Institute of Cognitive Neuroscience, UCL, London, UK
Journal reference: https://doi.org/10.1016/j.scog.2020.100181
Summary: Picture yourself noticing someone with an angry facial expression. The way you interpret this will depend on if that person is looking at you or away from you. This study investigates whether gaze direction and negative facial expressions are processed differently in individuals with psychosis.
Imagine yourself in a crowd. You notice a person displaying an angry emotional expression. Whether you worry about that person will depend on another important facial signal: is that person looking at you or away from you? Only an angry person looking towards you (but not away from you) may signal a threatening situation. Previous research in healthy participants has shown that observers are better at recognizing faces signalling threat, such as an angry face looking towards an observer or a fearful face looking away from an observer. Indeed, a person expressing fear signals threat to an observer if looking away rather than toward the observer. This is because a fearful face looking away may signal a danger in the close vicinity of the observer, such as a fire.
Gaze direction plays a crucial role in the interpretation of negative emotional expressions. Correctly interpreting the combination of gaze direction and facial expressions is therefore essential for survival. In the current study, the authors wanted to understand whether the processing of gaze direction and negative emotional expressions is intact in people with schizophrenia as compared to healthy controls. People with schizophrenia over-attribute threatening intentions to others. The current study aimed to assess whether this over-attribution of threat may stem from the early recognition of facial signals in others. To do so, the authors conducted a study in a group of healthy participants (21 participants) and a group of patients with schizophrenia (15 participants). Participants had to decide over several rounds whether different facial identities that rapidly appeared on the screen expressed anger or fear. These angry, fearful or neutral faces could either directly look at the participant or gaze away from the participant.
It has previously been established that people better recognize threatening facial expressions: an angry face with a direct gaze and a fearful face with an averted gaze. The results of the study here showed that this improved recognition of threatening facial expressions is intact in people with schizophrenia. Interestingly however, differences emerged between healthy participants and participants with schizophrenia concerning what explains this improved recognition of threatening emotions.
Let us unfold what is meant by this: thanks to computational modelling and decision theory, we can characterize the mechanisms underlying a better recognition of threatening facial expressions. Gaze direction can influence how an emotional expression is perceived in two possible ways. Let’s take the example of anger recognition: The first possibility is that direct gaze can enhance how well a person perceives an angry expression. In other words, direct gaze can increase the perceptual processing of a face signalling threat. This is found in healthy participants: they are able to better perceive anger in a face looking directly at them, i.e. they need less perceptual features of anger to judge a face as angry if it is looking at them as compared to if it is looking away from them. The second possibility is that direct gaze biases emotion recognition toward anger: this means that if a person has a completely neutral expression, an observer is biased toward interpreting the neutral face as angry if the face is looking toward the observer. The results in the study show that contrary to healthy participants, this second mechanism is what underlies the improved recognition of threatening facial emotions in patients with schizophrenia.
To conclude, the study shows that while in healthy controls, there is an increase in how well a threatening emotional expression is perceived, in patients with schizophrenia there is a bias in the interpretation of threatening emotions. This highlights that the over-attribution of threat to others in people with schizophrenia, which can lead to paranoid delusions, may stem from a maladaptive bias towards the judgement of self-directed threat.