You can make all kinds of claims about yourself but how can you ever know anything for sure about yourself or other people? There are a few methods you can try…

• Flow

This is a solution I devised to help make sure a persons read of themselves was clear. When a person is stressed or anxious, they are more likely to lie or put on a mask to hide their own personality from other people. If a person seems happy, balanced, stress-free and calm, their self-awareness is more likely to be accurate.

• Personality tests

Its one thing to say you are a certain person, but when asked various questions, does the person still receive the same or a similar result? Many people who type as say ENTJ may still come to answer more positively to questions that an INTJ would agree with more. This suggests the person they want to identify with is not the same as the person they actually.

• What do the experts think?

A lot of people rely on experts who have studied personality types for a long time for help. Experts can also have bias, so many experts look for reproducability, which is when a group of experts all do the same test to ensure the results are conclusive.

You also need to be able to reproduce the experts results, after being given the same information and reading through it and making sense of it, you should be able to review the conclusions and determine they are correct for you. Friends can also help, but you are better of asking them direct questions about your personality, such as “What do I appear to be the most confident about?” “When am I the most myself?” “What do you think I am interested in?”

Do NOT ask random people on the internet for help.

• Body language

Body language is a smart approach when used to back-up or double-check something. Some tips: Does the person appear calm and steady while they are being introverted? Does the person appear energetic and interested while they are using sensing? Does the person show passion or pride when using Feeling? Is the person stress-free and relaxed when using Perceiving? Then you may be dealing with an ISFP. 

• Body language patterns

The secondary approach is to look at other people who also type as ISFP and to check if there are similar patterns. Some keys I have noticed: Introverts hand gestures tend to start close to their body and then extend away from the body. Extroverts usually start with their hands further away from their body, with pulling or grabbing motions. iNtuitives tend to have more fluid wrist movements, and sensors tend to have more choppy motions.

Feelers tend to appear more relaxed in their finger movements, and thinkers more tense. Judgers tend to gesture with their palms facing the environment, perceivers tend to gesture with their palms facing themselves. Body language patterns do not prove anything and are more tendential, but they can help reinforce reads.

• Genetics and neuroscience
  

In the future, this may be possible as an additional verification: what correlations exist between which personality traits and which genes or neurochemicals?

• Critical thinking

Use critical thinking to verify a claim about a person or about a personality trait. These are the tricks I have devised over the years to evaluate personality psychology:

The Flow Test

I devised the flow test because it helped track a persons mood and energy depending on how they behave or deal with a certain situation. When a person was asked what situations made them feel more emotionally balanced, relaxed, energetic and passionate, they would be more likely to identify their right personality type.

The Jargon Check

A personality trait definition has to be simple enough for anyone to be able to understand and see in themselves and other people, but complex enough to not be a stereotype or oversimplification of someone’s behavior.

A stereotype tends to be too simple to be true: we know people cannot be divided based on if they are happy or sad, because most people are sad sometimes, and happy other times. We also know people can also not be divided based on if they are Raltsers or Pooshies because nobody knows what a Pooshy or Raltser is. 

The Forer Check

A personality statement can be too general or normal to have any meaning, for example, see the statement “You are sometimes happy, but you are also sometimes sad.” which would describe almost anyone. A personality statement can also be too specific or weird to apply to anyone: See “All INFJs have read “The Wheel Of Time”, and if they haven’t, they are not real INFJs.”

The generation test

The personality trait description you offer should be true about the person no matter their age, gender, or nationality. You should not use cultural or age-related descriptions to describe personality traits, or your definitions should track how a personality type grows from a young age to when older in life.

The Health Test

Two people of the same personality type should be stressed by similar activities, and feel relaxed in similar situations. If a judging type says they are stressed by thinking about goals, or a perceiving type says they are stressed by changes around them, that would suggest there is a contradiction. 

The Double Blind Test

If you train two people to use the same cognitive function definition or method to type a person, are they able to reach the same conclusion about a persons type or personality traits? If they cannot, it may be that their definitions or methods are too ambiguous. 

The Expert Check: The Two Broken Clocks Can Be Right At The Same Time (And Wrong Most Of The Time)

Just because there is an expert consensus on something does not mean it is correct. That is why experts need to be able to generalize and demonstrate their results have accuracy with the target group they study. This can be done by asking the test groups to rate their own results for their accuracy over time. Is the test group able to, over time, come to an agreement with the experts on the accuracy of their results? We need more quality standards and transparency to truly get data about the accuracy and meaningfulness of personality psychology. 

With these methods, perhaps we will be able to gain more understanding in the future. But right now, we have a long way to go.