With personality quizzes and buzzfeed questionnaires becoming so popular on facebook, it's easy for people to lump the MBTI into the same category; another stupid personality test with no basis in reality. What Harry Potter character am I? What breed of dog are you? The list goes on and on. A lot of the arguments I've heard against personality testing and the psychology of personality type is that people are comparing the MBTI with these popular, but basically useless and inaccurate tests. What people fail to realize is that the MBTI is based on a compilation of over 70 years of intense psychological research and has been proven to be useful in numerous real-life applications. You can find out more about this here. When it comes to the MBTI, a lot of the online tests are constructed inaccurately and have poorly worded questions that are going to make it hard to get the correct type result.

Avoid the online tests if you can!

Most of the free online Myers-Briggs quizzes are using the letter dichotomies (telling you that you're an I or an E, an F or a T, an N or an S, etc,..) rather than employing the underlying theory of type psychology - the cognitive functions.

What are these cognitive functions? 

There are 8 cognitive functions, and each personality type uses all of these, either consciously or unconsciously. These functions determine how you process information and make decisions. Consciously, everyone has two judging and two perceiving functions. Your perceiving functions determine how you take in information, and your judging functions determine how you make decisions with that information. 

So, say you're an INTJ. If this is you, then your cognitive functions fall in this order:
Dominant: Introverted Intuition
Auxiliary: Extraverted thinking
Tertiary: Introverted feeling
Inferior: Extraverted sensing

Knowing this basically tells us that as an INTJ you take in information through introverted intuition. This is also your dominant function so it is highly perfected. Next, you make decisions using extraverted thinking; which is your second most advanced function.  As an INTJ you would also have a tertiary function of introverted feeling, and an inferior function of extraverted sensing. The tertiary and inferior functions will not be as polished or keen as your dominant and auxiliary functions, but you still will use them and rely on them.


Okay, this is getting really confusing...what do all these things mean?

There are four main functions, and each one can be either introverted or extraverted. Let's start with the perceiving functions, these are sensing and intuition.


The Perceiving Functions




Introverted Sensing (Si):

Introverted Sensing deals primarily with recalling facts and details of past events. People with introverted sensing are able to recall past experiences with great accuracy, and they believe that the past is the greatest teacher for the future. They are very tradition-oriented and love holidays and family gatherings that are commemorated year after year. They love consistency, hard work, and they see their role as their duty; performing with pride all the details their role entails. The introverted sensor likes a predictable system and job security; change and unpredictability is very unsettling and can make them feel lost. 


Physically speaking, introverted sensors are more aware of what is going on inside their body. They may be the first to notice they are feeling sick or are having a physical reaction to something. They tend to be highly aware of inner bodily sensations such as hunger, thirst, numbness, etc,..

Personality types with dominant introverted sensing: ISTJ and ISFJ
Personality types with auxiliary introverted sensing: ESTJ and ESFJ


Extraverted Sensing (Se):Extraverted Sensing deals primarily with experiencing and perceiving the outside world in the present moment. Extraverted Sensors see, feel, touch, smell, and listen to everything that is going on in the external world. They are always taking in new experiences and sizing up the situations of the world around them. They live in the present moment and thrive on new and exciting experiences. They tend to love engaging in sports and enjoy experiences that will delight their senses; fine food, extreme sports, exotic trips. 


Extraverted sensors tend to become bored with routines, but at the same time are very practical and down-to-earth. People with dominant or auxiliary extraverted sensing tend to move gracefully, and be more aware of their surroundings and their own physical presence. They have quick reflexes and don't tend to enjoy sitting still for too long, unless engaged in something that excites their senses; like a challenging video game or an action-packed movie.
Personality types with dominant extraverted sensing: ESTP and ESFP
Personality types with auxiliary extraverted sensing: ISTP and ISFP
Introverted Intuition (Ni):

Introverted intuition is the ability to foresee implications and likely effects without external data. People with introverted intuition can often foresee what will be, and are very good at seeing patterns and predicting transformations
. They have "gut feelings" that are usually very accurate. They enjoy tinkering with ideas, perspectives, theories, visions, stories, symbols, and metaphors. They want to know what things "mean" not what they "are". 
People with introverted intuition are concerned with the big picture. They are extremely aware of hidden meanings, subtle patterns, and what those things could mean for the future. They tend to live in their heads, but at the same time, are able to pick up on outside patterns, symbols, and have a knack for picking up on "hidden clues". They can go from being the most absent-minded professor to the most aware detective. They are strategists who can put the puzzle pieces of the past and present together to create a future prediction.
Personality types with dominant introverted intuition: INFJ and INTJ
Personality types with auxiliary introverted intuition: ENTJ and ENFJ
Extraverted Intuition (Ne):
Extraverted Intuition deals with experiencing the outer world, noticing possibilities, and what could be. It deals with seeing how all things in life are interrelated, and allows the user to see the world in multiple different perspectives.

People with extraverted intuition often wonder, "If I change this, what will happen?". They tend to be very creative, and often have an entrepreneurial mindset. They have a desire to make things happen and make an impact to the world. They can get very excited about these possibilities, making them naturally charismatic. They make inspiring leaders and are often catalysts for change in the world.
Personality types with dominant extraverted intuition: ENFP and ENTP
Personality types with auxiliary extraverted intuition: INFP and INTP
The Judging Functions

The judging functions are what people use to decide what they will do with the information they've perceived. For example, if you're an ISFJ you will take in information through introverted sensing, and make a decision regarding what to do with that information through extraverted feeling. Make sense? Okay, so let's explain what the judging functions are.
Introverted Thinking (Ti):
People with Introverted Thinking want the world to make sense logically. They form an internal framework of how the world works. It is constantly being modified and improved through life experience and experiments. They are able to see how everything in the physical world is related. For example, someone with introverted thinking can find out how a car and all its parts work by relating it to some other system, such as a computer.
Introverted Thinking is also great at troubleshooting. They are great at analytical thinking, and problem-solving, and can be quick to fix a problem. They like to do things effectively, and often find short-cuts that other people haven't thought of. Some people may see this as laziness, however, it’s a form of perfectionism most Ti users have.
Personality types with dominant introverted thinking: ISTPs and INTPs
Personality types with auxiliary introverted thinking: ESTPs and ENTPs
Extraverted Thinking (Te):
Extraverted Thinking deals primarily with understanding and organizing the external world. Extraverted Thinking wants everything to make logical sense, and has very little patience for unproductive activities or mulling over the options.
Extraverted thinkers have the desire to control their environment, and can feel lost when they are not able to shape their own external world. They see things in a logical, sequential order and don't like to waste time. They want things done, and they want them done now. They are decisive and make quick decisions. It is a very action-oriented function. They are usually logical, objective, and fair.
Personality types with dominant extraverted thinking: ESTJ and ENTJ
Personality types with auxiliary extraverted thinking: ISTJ and INTJ
Introverted Feeling (Fi):
Introverted Feeling (Fi) is a function that deals with a person’s own individual feelings and beliefs. Introverted feelers want to figure out who they are and what they want out of life. They want to be true to themselves; and filter things through a lens of "good/bad". An introverted feeler is very self aware of who they are and their place in the world.
Introverted Feeling also develops close attachment to people, things, and places. Introverted feelers take a considerable amount of time to form these bonds, but each day they grow stronger. 
Personality types with dominant introverted feeling: INFP and ISFP
Personality types with auxiliary introverted feeling: ESFP and ENFP
Extraverted Feeling (Fe):
Extraverted Feeling deals with understanding others emotions and feelings in the present moment. Extraverted Feeling is very attentive to others and can just sense what others are currently feeling. Extraverted feeling is like a sponge, soaking up other peoples feelings and emotions and trying to respond to bring harmony. It is able to quickly assess the mood of the environment. It is also very skilled at changing the mood, whether they want to make it more upbeat or more solemn.
Extraverted feelers tend to be supportive and nurturing. They have strong emotions for those they are close to, and will go out of their way to make them feel good. The Fe user is very close to friends and family members. Extraverted Feelers tend to want a clean house and to look presentable to the world. They may feel it is their duty to help others, and go out of their way to find a role to fulfill that desire.
Personality types with dominant extraverted feeling: ESFJ and ENFJ
Personality types with auxiliary extravered feeling: INFJ and ISFJ
In conclusion...
As you can see, the MBTI is more than just a four-letter code that puts people in one-dimensional boxes. Everyone is a feeler, a thinker, a sensor, and intuitive. You just are more of one than the other. Everyone has extraverted and introverted qualities. The more you dig deep into the real MBTI and its processes, the more you will see that there is a real logic behind it all and that it has practical hands-on benefits for you and the people in your life.