The first function of the ISTJ is Introverted Sensing. The ISTJ uses Introverted Sensing to recall and remember facts, processes, and how things are typically done. The ISTJ is very attached to tradition and pastimes. Introverted Sensing tends to form strong memories, and can use them to understand how the future will be. Introverted Sensing is also good at remembering rules, ways of doing things, and how they should be done. This makes them very good in fields like accounting, finance, law, and other fields with strict rules and regulations.
The second function of the ISTJ is Extraverted Thinking. The ISTJ uses these functions to organize thoughts, ideas, and people. They are very good at understanding the sequential steps needed to complete an idea. They can readily organize the information that is presented to them and use it to help come to a conclusion or decision. The ISTJ likes to come to conclusions about things and tends to get annoyed with or discard ambiguous information that doesn’t help lead them to a decision.
The third function of the ISTJ is Introverted Feeling. The ISTJ develops this function a bit later in life. The ISTJ uses this function to develop more of their own internal feelings and morals about things. The ISTJ can form strong attachments to their friends and family. They remain loyal and will want to do whatever they can to help them. Though sometimes they may not be as tactful with their words as some might desire, their intentions are usually good.
The fourth function of the ISTJ is Extraverted Intuition. This function never really becomes a strength of the ISTJ and can sometimes get in the way of their dominant function Introverted Sensing. The ISTJ typically sticks to rules and traditions. This function deals more with possibilities and what could be. This function can cause a typically sure minded ISTJ to question themselves and their thoughts. This can be good if the ISTJs traditional ways aren’t working and they need something new to help stimulate them. However, the ISTJ prefers to return to their routine and more comfortable and predictable state.