

Text used with permission of CPP, Inc.

Some psychologists and many test-takers believe these types say a lot about how people think and interact. Since the ‘70s, researchers have published their findings on MBTI in a peer-reviewed Journal of Psychological Type.

However, others consider the test to be worthless.

University of Pennsylvania professor of psychology Adam Grant says it doesn’t stand up to scientific scrutiny. “In social science, we use four standards: Are the categories reliable, valid, independent, and comprehensive?” Grant posted on LinkedIn. “For the MBTI, the evidence says not very, no, no, and not really.”

Grant points out that the test ignores important personality features, such as the ability to stay calm under stress. Moreover, people often get different results when they retake it. Research shows “that as many as three-quarters of test takers achieve a different personality type when tested again,” Annie Murphy Paul writes in The Cult of Personality Testing.

Additionally, the test relies on all-or-none categories, even when spectrums might be more accurate. For instance, no one is completely introverted or completely extroverted. (Some versions of the test do include what percentage you score for each category though.)

Given all this controversy, you might think people would treat the test as just a curiosity, or at least take it with a grain of salt. Instead, many people use types as a schema for understanding the world. There are blogs that sort Disney characters into MBTI types and YouTube sketch videos that compare types. According to CPP, a company that administrates the MBTI, college and universities worldwide use the test, as do 89 of the Fortune 100 companies.

While there's plenty to criticize about the MBTI, it's easy to imagine that, if you put a group of people with the same personality type in a room together, you'll see a lot of similarities. Thanks to the popularity of online community-building sites like Meetup.com, MBTI personality groups, such as the one in the shopping mall, have actually materialized, allowing test-takers to meet up with other members of their type. Because the best kinds of friends are the ones who are just like you. Or, as Jerry Seinfeld put it in an episode of Seinfeld, “Now I know what I've been looking for all these years...myself! I've been waiting for me to come along, and now I've swept myself off my feet!”

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The young adults in the shopping mall are all the INFJ type—introverted (I), intuitive (N), feeling (F), and judging (J). According to David Keirsey’s Please Understand Me, a book about the Myers-Briggs types, INFJs are quiet, private people who like discussions and care intensely about helping others. The fact that I know this might be coloring my perception, but these traits all seem to come out at the meetup. One person speaks at a time, and comfortable silences break up the conversation. No one seems interested in small talk. Instead, they consider philosophy and personal issues.