Cognitive dissonance refers to a mental state resulting from conflicts and inconsistent behaviors. When individuals are confronted with information that is inconsistent with their thought system, they unconsciously resort to perceptual distortion, justification, or denial to reduce internal tension. This defense mechanism, which often leads to cognitive biases, can affect professional decision-making, especially in sensitive areas such as auditing, where objectivity and impartiality are essential. Recognizing this phenomenon is necessary to strengthen objective judgments and reduce systematic errors. Therefore, the present study presents the dimensions of auditors' heterogeneity: with a thematic analysis approach and identifies the most effective dimension with the interpretive structural modeling method. This study is considered exploratory in terms of methodology and mixed in terms of analysis. Because of the lack of a coherent framework regarding the dimensions of auditors' cognitive heterogeneity, the study attempts to identify these dimensions through thematic analysis using the thematic analysis method based on the analysis of previous research and interviews with several experts. Then, using a simple two-stage Delphi method, the reliability of the identified dimensions was analyzed, and finally, based on interpretive structural modeling, the most influential dimensions of auditors' cognitive heterogeneity were determined based on the opinions of the research experts. The statistical sample of the study includes 14 academic experts and auditing professors who are experts and have professional experience in the field of auditing, as well as members of the Auditing Standards Development Committee, who were selected based on the purposeful sampling method with a snowball approach in 2024. The results of the present study indicate 3 dimensions (overarching themes) for auditors' cognitive heterogeneity, which include conflict in cognitive values, heterogeneity in structural mechanisms, and inhibitory individual mechanisms, as well as the organizing theme of the aforementioned dimensions (cognitive-environmental conflicts, negative cognitive processing, cognitive mental tensions, heterogeneity after decision-making, heterogeneity in career goals, setting unrealistic standards, and impaired autonomy and performance), and 31 basic themes were identified. Also, the findings of interpretive structural modeling show that auditors' cognitive-environmental conflicts are the most influential dimension of auditors' cognitive heterogeneity. The results of this study can help policymakers, standard developers, and legislators to better understand the dimensions and positive and negative consequences of auditor cognitive heterogeneity, concerning strengthening ethical functions; Social and cultural auditors should take action to interact more dynamically with stakeholders and social contexts, and based on that, adopt the necessary incentive policies to encourage audit firms to increase audit quality and thus limit inefficient behaviors in auditing.