It’s a common misconception that types who have an “F” in their four-letter Myers-Briggs® type only use Feeling, but in reality they also have a Thinking side. Myers-Briggs® theory contains what we call function stacks, which describe how our minds work and give a clearer picture of the depth and nuances of each personality type than you get just by looking at the four dichotomies.

Each type has two Perceiving functions (Sensing and Intuition) and two Judging functions (Feeling and Thinking). The Judging functions are the ones we usually use to make decisions. Your four-letter type tells you which of these functions you use most comfortably, and whether or not each function is Introverted or Extroverted.

The Feeling types use Introverted or Extroverted Feeling as either their dominant or auxiliary process. The opposite of this process (Extroverted or Introverted Thinking) is their tertiary or inferior process. For example, an ISFJ has the following function stack:

• Dominant function: Introverted Sensing (Si)
• Auxiliary function: Extraverted Feeling (Fe)
• Tertiary function: Introverted Thinking (Ti)
• Inferior function: Extraverted Intuition (Ne)

And ENFJ is an example of a type with Thinking as their inferior function:

• Dominant function: Extraverted Feeling (Fe)
• Auxiliary function: Introverted Intuition (Ni)
• Tertiary function: Extroverted Sensing (Se)
• Inferior function: Introverted Thinking (Ti)

Thinking As A Tertiary Function

The tertiary function is the least talked about, and perhaps the most misunderstood, function. It goes by several names that hint at its role in our personalities. In their car model, Personality Hacker calls it the “10-year-old” to describe its maturity level. Psychologist John Beebe names it the “Eternal Child” after one of Carl Jung’s archetypes. It’s also called the “relief function.”

Most people develop their tertiary function sometime between their late teens and mid-life. It can show up earlier as well, though not as strongly. Typically, we’ll use the tertiary function when we’re feeling playful or creative. It’s a place we go to re-charge and relax. Since it’s not as well-developed as our dominant or auxiliary function, though, relying on it too much can leave us feeling off-balance.

Learn more about your Tertiary function here: How Each Myers-Briggs® Type Uses Their Tertiary Function

For INFJs and ISFJs

INFJs and ISFJs use Introverted Thinking (Ti) as their tertiary function. Their preferred decision-making function is their auxiliary Extroverted Feeling (Fe). When making decisions, they’re usually focused on creating and preserving harmony and making sure other people’s needs are met. Even so, these types can also become pretty comfortable using their Ti.

When necessary, INFJs and ISFJs can demonstrate very good critical and analytical skills, especially as they mature. Younger INFJs and ISFJs might struggle with things like objective conclusions and impersonal analysis, but it becomes easier as they get older (though they’ll still prioritize Fe when making decisions that involve people).

As INFJs and ISFJs get older, they’ll typically become more comfortable with using their Ti, especially in recreational activities. They might learn to enjoy problem-solving or strategy-based games. They often develop an interest in categorizing and sorting information and impersonally analyzing what they learn. They may hesitate to express a value or belief because they want to make sure it’s accurate, or “makes sense”. They are usually quick to root out inaccuracies and logical loopholes. Ti can offer them a comforting escape from their normal patterns of behavior and thought.

Since Ti is not one of an INFJ’s or ISFJ’s more mature functions, they need to make sure they balance it out with their dominant Introverted Intuition or Introverted Sensing and their auxiliary Extroverted Feeling. Otherwise, these types can become reclusive and/or rigid, ignoring or criticizing people who don’t agree with their conclusions.

For ENFPs and ESFPs

ENFPs and ESFPs use Extroverted Thinking (Te) as their tertiary function. Their preferred decision-making function is their auxiliary Introverted Feeling (Fi). They’re usually focused on preserving inner harmony, and aligning their decisions with their personal values. They are usually very open-minded and non-judgmental. Even so, these types can also become pretty comfortable using their Te.

Younger ENFPs and ESFPs often struggle with organization, follow-through, and objective logic. But as they mature and start to develop their Te side, they can learn to use their Thinking side to balance-out their preferred functions (though they’ll still prioritize Fi when making decisions).

ENFPs and ESFPs who develop their Te quickly notice when something seems inefficient or disorganized. They’ll start to use measurable facts and logic more readily, and have an easier time explaining themselves to others. Their Te can provide comfort by helping them manage their time and projects more effectively so they don’t feel so overwhelmed. Te can help them to break down long-term goals into bite-sized, sequential steps.

Since Te isn’t one of an ENFP’s or ESFP’s most mature functions, they do need to be careful to balance it out with their dominant Extroverted Intuition or Extroverted Feeling and their auxiliary Introverted Feeling. If they become too caught up in their Te side, they may start to seem blunt, tactless, and overly confident in their arguments.

Thinking As An Inferior Function

The inferior function is a weak spot for each personality type. In their car model, Personality Hacker calls it the “3-year-old” because it’s the least-mature of our four functions. It’s also sometimes called the “stress function” because it often shows up when we’re under stress.

Most people develop their inferior function later in life. Developing this function can help us to achieve balance. When it’s suppressed or never developed in a healthy way we run the risk of over-working our other functions and falling “into the grip” of our inferior function. Types “in the grip” do not act like themselves and often feel confused, irritable, and stressed.

Learn more about your inferior function here: The Biggest Weakness of Every Myers-Briggs® Personality Type and What Does Each Myers-Briggs® Type Look Like When They Get Stressed-Out?

For ENFJs and ESFJs

ENFJs and ESFJs use Introverted Thinking (Ti) as their inferior function. Their preferred decision-making function is their dominant Extroverted Feeling (Fe). They’re usually focused on creating and preserving harmony and making sure other people’s needs are met. They are good at strategically organizing systems (using their inferior Ti and their dominant Fe) to ensure that goals for people are achieved. They often have a hard time accessing their Ti side and may struggle with using it in a healthy way.

Inferior functions can often show up in favorite hobbies. ENFJs and ESFJs might use it when studying a non-fiction subject they’re interested in or playing a logic-based game. When under stress, inferior Ti can make ENFJs and ESFJs critical of self and others. They might also withdraw from people and feel unhappy with themselves. They can get stuck in convoluted thinking patterns and start to seem rigid, paranoid, and negative because they’re trying to solve problems using a function that’s not well-developed for them.

Because Ti is the least-developed function for ENFJs and ESFJs, they often struggle with trying to make decisions based only on impersonal, factual data. They would much rather focus on the human factor. That isn’t a problem in and of itself, but developing Ti can provide balance that helps them be more objective and reasonable when need-be.

Developing inferior functions should be done during times of low-stress. Here are a few suggestions for developing Introverted Thinking:

• Come up with a new way to organize something in your home
• Learn a strategy game
• Use precise language to write a fact-based report on something that interests you

For INFPs and ISFPs

INFPs and ISFPs use Extroverted Thinking (Te) as their inferior function. Their preferred decision-making function is their dominant Introverted Feeling (Fi). They’re usually focused on preserving inner harmony, and aligning their decisions with their personal values. They tend to be very open-minded and non-judgmental. They can have a hard time accessing their Te side because they naturally give Fi priority. As such, they may struggle with using it in a healthy way.

Inferior functions can often show up in favorite hobbies. INFPs and ISFPs might see their Te show up as a fixation with to-do lists or a love of organization. They enjoy finding effective ways to create plans that coincide with their values and beliefs. When INFPs and ISFPs are stressed, inferior Te might cause them to become uncharacteristically harsh or judgmental. They may become obsessive about trying to fix problems or even create problems where none existed before. They might try to control and organize everything around them, struggling to bring order to their lives using a side of their personality that they’re not really comfortable with.

Since Te is their least-developed function, INFPs and ISFPs often struggle to remain objective or find efficient ways of translating their dreams into action. They’re much more comfortable making decisions based on personal values, morals, and emotions. When these types develop Te, it can help them balance-out their other functions and become more efficient in their decisions and in achieving goals.

Developing inferior functions should be done during times of low-stress. Here are a few suggestions for developing Extroverted Thinking:

• Set a goal and break it into actionable steps
• Plan a logical debate with someone you trust about an issue that isn’t deeply personal for you
• Find a way to make one of your everyday tasks more efficient

Conclusion

Understanding how Thinking plays a role in the personalities of INFJs, ISFJs, ENFPs, ESFPs, ENFJs, ESFJs, INFPs, and ISFPs gives a more well-rounded perspective on the Feeling types. There’s no such thing as someone who purely uses Feeling without Thinking (or vice versa). Rather, we each have one decision-making function that we prefer and one that we can develop to help balance-out out personalities.

Marissa Baker is the author of The INFJ Handbook (available in the Amazon Kindle Store). You can find her online at LikeAnAnchor.com where she blogs about personal growth and development from a Christian perspective.