This dissertation consists of three independent studies.

• In the first part of the dissertation, considering the multitude of factors affecting the professional judgment of independent auditors, the lack of clarity in the concept of major auditing issues, and the ambiguities in the judgment and decision-making process in this field, considering that no comprehensive research has been done in this field so far The main goal of the current research is to provide a model for judging and making decisions regarding the notification of major auditing issues, considering the environmental characteristics and conditions governing the auditing profession in Iran.

• In the second part of the thesis, according to the primary evidence of the implementation of this standard in the companies listed in the Tehran Stock Exchange, the auditors' decision-making process in order to implement this standard in practice, the consequences of this notification are examined.

• In the third part of the thesis, in response to the concerns and questions of the standard-setting bodies regarding the impact of informing the major audit issues on the decision-making process of the users, using the eye tracking approach, the role of directing the attention of the major audit issues has been evaluated and to examine how this affects Informing about the process of obtaining information by users.