There are three sources of employee expectations:

First, communication with other members of the organization. For example, in the recruitment process, recruiters introduce the company to new employees; The direct supervisor of an organization member usually communicates with him formally or informally, and so on. However, these effects on employees' psychological contract are different. Turnley & Feldman's empirical research shows that organizational members attach importance to formal or casual commitments made by direct superiors or senior managers, and if they fail to fulfill them, they will easily violate the psychological contract, while recruiters or colleagues in human resources departments have relatively little influence on the psychological contract.

Second, employees' perception of organizational culture. Organizational culture can restrain, guide and motivate individuals, which not only implies the expectation of the organization to its members, but also implies the commitment to its members. Therefore, employees also regard their perception of organizational culture as part of the psychological contract.

Third, the usual behavior of the organization. It is also possible for employees to observe typical organizational practices, explain the historical laws of organizational practices, and get their own expectations, and take them as part of the unwritten agreement with the organization.

The specific factors that lead to the breakdown of psychological contract mainly focus on the following aspects: salary level, performance pay, welfare treatment, job security, training development, promotion opportunities and work itself. These factors have different values for different employees. For example, older employees pay more attention to job security, while young people tend to pay more attention to training and development, promotion opportunities and job challenges.

The characteristics of breach of contract itself mainly refer to the scope, time difference and nature of breach of contract.

First, the degree of dishonesty. Generally speaking, the greater the gap between the promised return and the actual return, the more likely employees are to experience psychological contract violations.

Second, the time difference between commitment and dishonesty. Generally speaking, the longer the interval between them, the less likely employees are to perceive violations.

Third, the nature of dishonesty. It is found that people generally divide the reasons for violating psychological contracts into three categories: one is inability to cash; Second, unwilling to perform; Third, the understanding is inconsistent. Obviously, if employees attribute the reason for breaking their promises to the unwillingness of the organization to fulfill them, they are more likely to experience violations; However, if employees think that the organization is honest and credible, and the differences may be caused by some misunderstandings or external forces beyond the control of the organization, it is unlikely to interpret the differences as violations.

(2) The moderating variable of psychological contract violation.

Breach of psychological contract will reduce employees' loyalty to employers, satisfaction with work and organization, and reduce employees' willingness to stay and sense of responsibility to the organization (Robinson &; Morrison,1995; Robinson & Rousseau, 1994). Moreover, violation of regulations has a negative impact on employees' behavior, leading to those valuable employees reducing their contribution to the organization or leaving their jobs. In addition, violations may lead to expensive legal proceedings and affect the reputation of the organization. However, not all psychological contract violations will lead to employees' negative behavior, and there are still a series of moderating variables between them. As shown in figure 1.

According to Turnley and Feldman, as far as the characteristics of individuals are concerned, those individuals with negative emotions, strong sense of fairness and integrity will often react negatively once they experience aggression. As far as the organization's practice is concerned, if the reason for the difference is procedural fairness, the organization informs employees in a respectful and polite way, or the organization takes a series of remedial or compensation measures, or employees maintain a high-quality working relationship with responsible colleagues, then employees are unlikely to make negative reactions. Judging from the external labor market, if the flow cost is high and the employee's replacement is high, there will be