Cognitive functions are core concepts in MBTI theory that describe how people receive information and make judgments. Jung divided psychological activities into two categories: Perceiving functions (Intuition N and Sensing S) for gathering information, and Judging functions (Thinking T and Feeling F) for making decisions. Each function is further divided into “extraverted” and “introverted” depending on whether attention is directed outward or inward, resulting in eight functions: Ne, Ni, Se, Si, Te, Ti, Fe, Fi. Importantly, each MBTI type does not use these eight functions equally; there are dominant, auxiliary, tertiary, and inferior functions in a hierarchy. This ordering is the function stack, and it is key to distinguishing the thinking styles of the sixteen personality types. Understanding this framework is the first step in MBTI cognitive function analysis.

Among the judging functions, Feeling (F) makes decisions based on “values,” and Fi and Fe show two distinct directions. Fi (introverted Feeling) focuses on personal inner values and authentic feelings. People who use Fi tend to ask themselves, “Is this true to me? Does it align with my beliefs?”—often giving an impression of being true to themselves and valuing personal principles. In love and relationships, they prioritize deep, genuine connections. Fe (extraverted Feeling), on the other hand, focuses on group emotions and harmony. It excels at sensing others’ feelings, creating a harmonious atmosphere, and being willing to adjust to maintain relationships. This doesn’t mean Fe lacks principles or Fi doesn’t care about others; rather, they prioritize different aspects when processing emotional information. Understanding the difference between Fi and Fe helps us appreciate the diverse ways people express care.

The Thinking (T) function judges based on “logical consistency,” and Ti and Te again show internal vs. external differences. Ti (introverted Thinking) seeks a self-consistent internal logical framework. People who use Ti like to dissect problems, clarify definitions, and ensure every inference holds up within their own system—often appearing analytical and precise. Te (extraverted Thinking) focuses on how to efficiently organize the external world, emphasizing practical results, processes, and measurable outcomes. It tends to use objective data and established norms to get things done, excelling in execution and management. Simply put, Ti asks “Does this make sense logically?” while Te asks “Is this practical and efficient?” By comparing Fi, Fe, Ti, and Te, we can see the core logic behind different personality types’ decision-making.