ISTJ Functions and Characteristics

Every human being has a different personality, which explains differences in characteristics, attitudes and behaviors. This is referred to as a “personality type,” which is a psychological classification of different types of individuals. These personality typologies were developed to better understand each person. These also allow effective prediction of clinically relevant information about people in order to formulate treatment strategies.

Carl Jung was one of the prominent psychiatrists who have the most significant theoretical work from which these influential ideas have originated from. His profound interest in typology was derived from his earnest desire to reconcile Sigmund Freud’s and Alfred Adler’s theories. He also wanted to determine and understand how different his and their perspectives differ. Jung later on concluded that Adler’s theory was introverted and Freud’s was extraverted. He was convinced that the difference between the Freudian and Adlerian theories were due to the unrecognized existence of various fundamental psychological attitudes.

Jung categorized people in his book into primary types of psychological function. He suggested there are two dichotomous pairs of cognitive functions: ration (judging) and irrational (perceiving). He also proposed that these functions are manifested in either extraverted or introverted manner.

One of the personality types used in the Myers-Briggs Type Indicator, which was developed from Jung’s work, is ISTJ or (Introversion, Sensing, Thinking, Judgment). People with this personality type are driven to create, responsible and are orderly. Today, there are around 10 to 14 percent of the population who have this personality type.

But what exactly distinguishes an ISTJ personality from other types? Let us take a look at the unique characteristics and functions of this personality type.

ISTJ Characteristics

1. ISTJs know their place in life.
Despite being introverted, people with this personality type are seldom isolated. Their aim in life is to know how they can participate in established systems as they are particular in maintaining ode and making sure that things comply with standards.

2. ISTJs are often reserved and serious.
They are always dependable and thorough, making them successful in everything they do. They have the rare ability to shut out anything that distract them, ensuring that they take a logical and practical approach to whatever they are doing.

3. ISTJs are able to make difficult decisions that other personality types often avoid.
They are able to weigh out all options to ensure that they will make informed decisions.

4. ISTJs can always be seen as working hard.
They are often striving towards the fulfillment of their goals. They are also detail-oriented. They do not stop until the job is completed.

5. ISTJs learn easily.
What is really great about people with ISTJ personality is that they immediately apply the subjects that are practical to them. But they need teachers, directions and materials to ensure that they understand and trust the information they have.

6. People with ISTJ personality also like learning activities that allow them to think and reflect.
They tend to be skeptical with materials that may be too easy or too fun. ISTJs also delineate between play and work because of their practical outlook. This means that they prefer a learning environment that is task-oriented, has a clear assignment and has a clear schedule.

7. ISTJs are honest and straightforward.
At the heart of ISTJ is integrity. This is why they can’t be accused with mind games, lies and emotional manipulation. They prefer to manage situations with plain and simple honesty.

8. ISTJs support facts.
Through their sensing function, people with ISTJ personality have store huge amounts of data within themselves. They could have difficulty believing an idea or theory that might be different from their own. But if someone they respect and care about explains the data to them, they will treat the idea as a fact, which will be internalized and supported.

9. ISTJs are hard working.
They are known for working long hours and devoting their energy to things that are crucial to fulfilling a goal, except for when things don’t make sense to them. Although they prefer to work alone, they could function in a team, as well.

10. ISTJs are stubborn, insensitive and judgmental.
They seem to not be open to criticism as they cannot accept that they were wrong about something. Sometimes, they also don’t like people disagreeing with them, especially those who don’t know the facts.

ISTJ Functions

Dominant: Introverted sensing (Si)

This function gathers data in the present moment and makes a comparison with the past. This is what ignites feelings associated with memory, making the person feel as if he is reliving the moment. To protect what is familiar, Si form goals and expectations from history. Using this function, ISTJs often have deep analysis of what is around them.

Auxiliary: Extraverted thinking (Te)
ISTJs schedules and organizes ideas to ensure efficient and productive objectives. This function also makes people seek logical explanation for events, conclusions and actions. They also find fault in reasoning and lapses. This is especially helpful in actively processing and evaluating perceptions.

Tertiary: Introverted feeling (Fi)
With this function, ISTJs are able to filter information according to interpretation of worth, as they make judgments based intangible criteria. The Fi function also balances internal values such as authenticity and harmony. This also allows individuals with ISTJ to determine what is true and what is false in a situation. Furthermore, this enables them to understand how they feel and what causes it.

Inferior: Extraverted intuition (Ne)
Using “what if” questions, this function searches and interprets hidden means to find other options, ensuring that there are multiple possibilities. To form a new whole, this function weaves insights and experiences together from various sources. As a result, this can result to action. ISTJs are quick to process information and numbers, but they have a hard time with abstract concepts with no concrete applications.


The ISTJ personality makes people dominant and excel in their fields. This is why many of those who have this personality type are prominent personalities. However, they can also be stubborn, judgmental and insensitive to others.