**2. Literature Review**

#### *2.1. Research on TMT Characteristics Based on the Upper Echelon Theory*

Based on the cognitive basis and values of decision makers, Hambrick and Mason (1984) [9] explored the theoretical framework of enterprise strategic decision making and creatively put forward the upper echelon theory. Hambrick and Mason (1984) [9] argued that the behavior of senior managers is a response to their cognitive, value, and experience characteristics. By influencing team cognition, TMT characteristics enable them to make different judgments on alternative plans, future events, and corresponding results, thus affecting strategic decisions and ultimate outcomes. This theory aims to optimize the characteristics of TMTs to improve the team's operation level and subsequent enterprise performance [12,13]. The characteristics of TMTs proved to be an important factor affecting management and even corporate behavior [21].

Scholars have made many achievements in exploring the relationship between TMT characteristics and organizational performance. These scholars mainly focus on two aspects of TMT characteristics: the team's demographic characteristics and heterogeneity. In the face of the complex external strategic environment, executives will bring personal psychological factors (cognitive type, values, personality, etc.) and observable factors (age, gender, education, etc.) into the strategic decision-making process [19]. The advantage of using demographic characteristics for academic research is that it is simple and objective, easy to understand, easy to measure, and has a good predictive effect [22]. TMT heterogeneity refers to the differences in demographic background characteristics and important cognitive concepts and values among senior management members [23]. Theoretically, such differences can cover countless dimensions, including easily identifiable differences such as age, gender, race, educational background, functional experience, and industry experience (as well as differences such as personality and values that are difficult to measure specifically) [7,24]. In fact, considering the availability of data, most of the existing studies focus on the heterogeneity of easily identifiable and stable characteristics. Many organizations and strategically minded researchers apply the upper echelon theory to study the relationship between TMT heterogeneity and organizational performance [24,25]. With the increasingly complex decision-making environment and the increasing difficulty of decision making, heterogeneity has attracted more and more attention [18,26–28]. However, the research on TMT experience heterogeneity is still insufficient.
