This mistyping makes sense. ISFJs have Extroverted Feeling as their auxiliary function and Introverted Thinking as their tertiary function, the same as INFJs. ISFJs make up anywhere from 9-14 percent of the population, so INFJs who are focused on trying to fit in with the status quo or who grew up in sensory-focused environments may be more likely to mistype as ISFJ.
Since Ni is an introverted function, INFJs may appear at first introduction a lot like ISFJs — quiet, people-oriented, calm, and friendly. This is due to their shared first extroverted function, Fe. However, INFJs and ISFJs are different in several major ways — the biggest being dominant intuition vs. dominant sensing.
The dominant function for ISFJs is Introverted Sensing (Si). Si is all about the focus on past experience and holding onto tradition and values. It’s about recalling details from the past and using that knowledge to do things in the ways that they’ve been done before. Guess where Si falls on INFJs functional stack? Last. Because of this, INFJs can become extremely stressed out when having to remember exact sensory details.
For example — an ISFJ and an INFJ work together in a coffee shop. The ISFJ is taught the best way to make a specific drink, and so will make that drink that exact same way every single time. The INFJ, however, will instead remember the general idea of how the drink was made, but won’t be as concerned about measuring out the amount of this or that, and will likely even experiment with the ingredients occasionally. The exception would be if the INFJ felt a lot of pressure to make the drink exactly right, in which case they would focus even more so on doing things as they should be done, which would cause a high level of stress. ISFJs, like other Guardian types, tend to be more task and detail-oriented, whereas INFJs, like other Idealist types, tend to be more idea and big picture-focused.
The dominant function for INFJs is Introverted Intuition. While Si is focused heavily on the past, Ni is focused heavily on the future. Ni looks for symbolism, patterns, and deeper meanings behind ideas and concepts. INFJs are known to speak in metaphors and make connections between both sensory objects and abstract ideas. Ni is the last shadow function for ISFJs, who greatly prefer to focus on concrete past or present-oriented thoughts and ideas.
For example — an ISFJ and an INFJ are looking at the same image of a mother playing with her young daughter. The ISFJ will describe the image for exactly what it is and/or use past experience to describe how it relates to her life — “This is an image of a mom playing with her daughter. It reminds me of when my mother and I used to play together in the park when I was a kid.” The INFJ will instead describe the image in a more abstract way, focusing on what it represents and future implications — “This image represents love and the strong bond between a mother and daughter. No matter how old the daughter gets, she’ll always have these special moments with her mother to remember.”
Both INFJs and ISFJs auxiliary Fe make them types who enjoy helping others, yet they prefer to do so in different ways. ISFJs’ Si-Fe pairing make them excellent caregivers. They prefer to help others by taking care of them. ISFJs make excellent nurses, teachers, and are the quintessential mother type. INFJs’ Ni-Fe pairing make them great counselors. They prefer to help others by helping them understand themselves and offering advice.
Hopefully this article helped to differentiate between INFJs and ISFJs. In the next article in this series, I’ll examine the differences between INFJs and ENFJs.