Facial emotion recognition results
According to the results of this study, both the control group and the schizophrenia patient group had emotion recognition disorders. The two groups were similar in terms of identification rate and error patterns. Both groups had the highest accuracy rate of neutral expression recognition and the lowest recognition rate of fear. Furthermore, both groups tended to identify happiness as neutral and anger as happiness. This result may be due to the same sociological basis of emotional recognition in healthy people and patients, which is formed during the process of socialisation. The patients maintained their original social cognitive characteristics even after disease onset.
Our studies have found differences between the two groups in the identification of neutral emotion and anger. The correct identification rate for neutral emotion in the patient group was lower than that of the control group, with the patient group tending to identify neutral emotions as happiness. The control group tended to identify anger as happiness, and the patient group tended to identify anger as fear. The facial emotion recognition process is often influenced by an individual’s previous social experience. While the control group understood the real thinking behind the emotion, the patient group remained at the superficial level of the face and was affected by thinking disorders. The difference in the recognition process may be the psychological factor of this difference. Yao et al.  showed that patients with first-episode schizophrenia had facial emotion recognition disorders before medication, and the injury of the frontal white-matter fibre may be the basis of pathophysiology. Therefore, more research is needed to further understand this difference.
The results of the current study showed that the overall recognition rate of facial emotions was negatively associated with the age of onset and had no correlation with disease course, age or duration of education. Neutral emotions, happiness, anger and fear were not correlated with disease course, age, age of onset or duration of education. Chen et al.  showed that male patients with schizophrenia were stable during the course of emotion recognition disorder. A meta-analysis by Kohler et al.  revealed that the age of onset was moderately associated with emotion perception. The later the age of onset, the greater the injury. However, the age of onset was not significantly associated with the course of the disease, which is a similar result to that of our study.
However, there are also inconsistent findings. Hofer et al.’s  studies on outpatients found that emotion recognition was positively associated with education and negatively associated with increasing age. Zhu et al.  showed that the accuracy of overall facial emotion recognition and angry faces were negatively correlated with the disease course of patients. In the present study, the patients were older and had a long disease course, but the results showed that the patients’ facial emotion recognition impairments did not worsen further with a prolonged disease course, suggesting that facial emotion recognition impairments in patients with schizophrenia may be a functional impairment that is independent of the disease.
Facial emotion recognition impairments in schizophrenia occur from the first episode of the disease  and are also present in patients’ children and siblings [15, 16]. As the disease develops, facial emotion recognition disorders show stable features . Moreover, the scores of aphasia recognition tests and the recognition scores for sadness, panic, fear and anger in the eye area of emotion tests in patients with schizophrenia were lower than those in healthy controls . All these studies suggest that deficits in social cognitive function may be schizophrenia-specific impairments, indicating that they may be genetic endophenotypes of schizophrenia.
Facial emotional recognition and psychiatric symptoms
This study showed that the identification of happiness was correlated with psychiatric symptoms and negatively associated with negative symptoms, general pathology and total scale scores, while it had no correlation with neutral emotion, anger or fear. The total score for facial recognition showed a negative correlation with negative symptoms and no correlation with positive symptoms. This result is not consistent with those of previous studies [2, 12], and it may be related to the higher age, longer disease course and more prominent negative symptoms in this study. The patient still has positive residual symptoms, but the impact on the patient was weaker than their negative symptoms and general pathological symptoms. The more severe the psychiatric symptoms in the study, the lower the recognition rate for happiness.
Patients may be affected by their moods when recognising facial emotions. In this group, the patients had dull emotions, anhedonia and less happiness experience. The identification results also reflected the mood of the patients to some extent, which may be the reason that it significantly affected only the identification of happiness. The results differ regarding the correlation between facial emotion recognition and psychiatric symptoms. However, these results still suggest that when designing social skills training programmes, we need to increase certain elements to improve negative symptoms and initial motivation, apply cognitive and behavioural therapy techniques promptly, correct the core beliefs, reduce pathological thinking interference, improve social cognition levels and reduce the negative effects of psychiatric symptoms.
Facial emotion recognition and interpersonal communication
The results showed that the correlation between the IRIDS total score, each factor score and emotion recognition accuracy (except happiness and conversation) was not statistically significant. However, the correlation between the SSC total score, the score for each factor, and the happiness and anger recognition rates (except happiness and conflict resolution) was statistically significant. Happiness recognition was negatively associated with conversation factors, showing higher happiness recognition to be correlated with low conversation disturbance. They were good at using the appropriate form of language to exchange ideas, but conversation without trouble cannot cover up or offset issues with communication, interpersonal behaviour and heterosexual communication. In general, the correlation between the accuracy of facial emotion recognition and the subjects’ self-perception of interpersonal disturbance was not obvious, reflecting that the patients did not recognise interpersonal disturbances, indicating a defect in their interpersonal self-perceptions. Facial emotion recognition was significantly associated with social skills, and it affected social skills. The higher the accuracy of the identification, the less impaired the social skills. The results also showed that the identification results for happiness and anger affected interpersonal interactions more than neutral emotions and fear. In interpersonal communication, whether or not we can correctly identify happiness and anger has a great impact on social communication skills. In the process of social communication, emotional recognition is an important link. Only with the correct emotional interpretation can there be proper emotional expression, and language communication can occur smoothly within the correct emotional interaction. In interpersonal communication practice, the importance of emotional communication exceeds even that of language communication; this reminds us to consider facial emotion recognition and interpersonal self-perceptions when designing interpersonal communication training.
This study has the following limitations: The stimulus images used in the study were computer-synthesised Chinese facial expressions, without difficulty classification, an internal consistency test or a validity test. In addition, the test tool was in a static image format, but real expressions are dynamic, continuous and contain emotional interaction and communication. Whether or not there are differences in the recognition results of static images and dynamic expressions, we need to develop new testing tools for in-depth research. Previous studies have shown differences between different genders, with women with schizophrenia performing better than men in terms of facial emotion recognition [19, 20]. There are significant gender differences in the pattern of error rates in male and female patients , although our study subjects were of a single gender. The lack of female subjects, the small sample size of the patients and the lack of differential analysis of the images of the emotional faces of different genders are the shortcomings of this paper. All these problems need to be supplemented and improved in subsequent studies. The social cognition used in the study also includes the theory of psychology, and corresponding test tools have been developed  to assess the severity of cognitive impairment in the psychological theory of schizophrenia. In the future, prospective studies of standardised interventions can be designed based on the comprehensive assessment of social cognitive disorder in schizophrenia to accumulate evidence-based medical proof and provide further support for clinical practice.
In conclusion, veterans with chronic schizophrenia have impaired facial emotion recognition, the accuracy of which is negatively associated with the age of onset and is affected by negative symptoms.