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Articles > The ISTJ Personality Type

The ISTJ Personality Type

Serious, principled, and systematic, the ISTJ gets right to the point.

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This series of short articles touches on several aspects of the ISTJ personality type.

You can jump straight to any section by clicking the links below, or keep reading to learn about the definition of the ISTJ personality type.

What does ISTJ stand for?

ISTJ stands for Introverted, Sensing, Thinking, and Judging.

In the popular Myers-Briggs or 16-personalities tradition, all personalities belong to one of 16 types. Each type is defined by preferences across these four dimensions:

  • Introverted vs. Extraverted
  • Sensing vs. Intuitive
  • Thinking vs. Feeling
  • Perceiving vs. Judging

Here’s how to understand the ISTJ’s place on all four dimensions:

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ISTJs have an introverted attitude or orientation.

ISTJs tend to focus more on the inner, subjective world of concepts and ideas, while an extraverted attitude leads to a greater focus on the external world of objects and people.


ISTJs prefer to use the cognitive function of sensing over intuition when taking in information about the world.

This dimension, sensing vs. intuition, is known as the perceiving function in MBTI theory.

Sensing refers to perceiving and gathering information directly through the sensory system. People who prefer sensing trust their five senses to directly observe the world, and they can be more skeptical of more intuitive, theoretical approaches to learning and understanding.


ISTJs prefer using their thinking function when judging information and assessing values and needs among people.

This dimension, thinking vs. feeling, is known as the judging function in MBTI theory.

By prefering thinking over feeling as their judging function, ISTJs lean heavily on logic, consistency, and correctness when making decisions, rather than focusing on others’ emotions, desires, and perceptions.


As a judging type, ISTJs tend to present their judging function of thinking to the external world.

Because they present their thinking function externally, other people see ISTJs as logical, rational, and highly analytical.

ISTJ cognitive functions

The four-letter types from MBTI theory encode each type’s attitudes and preferred cognitive functions.

  1. The first letter indicates an introverted vs. extraverted attitude
  2. The second letter indicates the preferred sensing function
  3. The third letter indicates the preferred judging function
  4. The fourth letter indicates a judging vs. perceiving attitude

For the ISTJ,

  • I: This type has an introverted attitude
  • S: This type prefers perceiving through sensing over intuition
  • T: This type prefers judging through thinking over feeling
  • J: This type has a judging attitude or orientation and will present their favored judging function (thinking) to the outer world

From this, we can determine how the ISTJ prefers the four cognitive functions of intuition, sensing, thinking, and feeling:

  • ISTJs’ primary function is sensing (S)
  • ISTJs’ secondary (auxiliary) function is thinking (T)
  • ISTJs’ tertiary function is feeling (F)
  • ISTJs’ inferior function is intuition (N)

Why? ISTJs have an introverted attitude (I) and a judging attitude (J), so they present their judging function (T) to the external world.

However, as an introverted type, ISTJs prefer an orientation to the inner world, so their primary cognitive function is not what they show to the external world. Instead, their primary cognitive function is their perceiving function: sensing or sensory perception (S).

ISTJs’ secondary function is the one they show to their external world: thinking. This counterbalances their introverted primary function.

In MBTI theory, the tertiary function is the opposite of the auxiliary function, which for ISTJs is feeling.

Lastly, the inferior function is the opposite of the primary function, which for ISTJs is intuition. The inferior function in all personality types is the least developed function.

How rare is the ISTJ personality type?

According to the MBTI, somewhere between 5% and 30% of all people will be classified as an ISTJ. The rarity of the ISTJ varies based on the version of the MBTI assessment and the demographic makeup of the sample.

ISTJ compatibility with other types

For comparisons between ISTJs and other types from the 16 Personality typology, visit any of the type pairings below:

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