The Short Answer
The -A or -T after a type like INFJ-T or ESTP-A stands for Assertive or Turbulent. It describes how confident and even-keeled you tend to feel, especially under stress:
- Assertive (-A): more self-assured, less prone to worry, and quicker to bounce back from setbacks
- Turbulent (-T): more self-conscious and sensitive to stress, and more driven by a sense that things could be better
This fifth letter comes from the 16Personalities test. It’s not part of the official Myers-Briggs Type Indicator, which only has four letters.
Where the Fifth Letter Comes From
16Personalities is a free online test that uses the familiar four-letter MBTI-style codes. It calls the extra dimension “Identity” and adds it to every result, so an INTP becomes either INTP-A or INTP-T. The official MBTI, published by The Myers-Briggs Company, has no equivalent letter. Neither does Jung’s original theory, described in Carl Jung’s psychological types.
16Personalities also renames some MBTI terms. For example, Sensing becomes “Observant.” See intuitive vs observant for that change.
Assertive (-A): What It Describes
People who score as Assertive tend to:
- Feel reasonably confident in their abilities and decisions
- Stay relatively calm when things go wrong
- Move on from mistakes without dwelling on them for long
- Worry less about how others see them
The possible downside is that this ease can tip into overconfidence: preparing too little, missing warning signs, or dismissing useful criticism.
Turbulent (-T): What It Describes
People who score as Turbulent tend to:
- Be more self-critical and aware of what could go wrong
- Feel stress and pressure more keenly
- Care more about how they come across
- Keep pushing to improve, sometimes toward perfectionism
The upside is that this restlessness can drive careful preparation, attention to detail and steady self-improvement. The downside is a higher risk of feeling overwhelmed, second-guessing decisions, or burning out.
Assertive vs Turbulent at a Glance
| Assertive (-A) | Turbulent (-T) | |
|---|---|---|
| Typical self-view | Confident, settled | Self-questioning, striving |
| Response to stress | Steady, takes it in stride | Feels it strongly, may worry |
| After a setback | Moves on fairly quickly | Reflects on it, may ruminate |
| Feedback | May shrug off criticism | Takes it seriously, sometimes too seriously |
| Strength | Resilience, composure | Conscientious preparation, drive to improve |
| Risk | Overconfidence, complacency | Self-doubt, stress, perfectionism |
How It Relates to Neuroticism in the Big Five
The Big Five, the trait model most used in academic personality research, includes a dimension called neuroticism, sometimes framed by its opposite, emotional stability. It describes how readily a person experiences negative emotions such as worry, irritability and sadness.
The Assertive–Turbulent scale appears to overlap heavily with this trait. Assertive results broadly line up with lower neuroticism, and Turbulent results with higher neuroticism. This is one reason many people find the fifth letter genuinely informative. The four MBTI letters say little about emotional reactivity, so A/T adds something the classic letters leave out.
Is One Better Than the Other?
Neither result is better overall. Each is a mix of advantages and costs, and the mix depends on context. A calm, Assertive approach can be valuable in a crisis. A Turbulent eye for what might go wrong can be valuable when checking a plan or caring for details.
A few cautions are worth stating clearly:
- Turbulent isn’t a diagnosis. It describes a common personality tendency, not anxiety disorder, depression or any other condition.
- Assertive doesn’t mean healthy, and Turbulent doesn’t mean unhealthy. Wellbeing depends on many things besides personality.
- If you’re struggling, for example with persistent worry, low mood or stress that gets in the way of daily life, that’s worth raising with a doctor or a qualified mental health professional, whatever your test result says.
Can Your A/T Result Change?
It can, and it may change more than your four letters do. How confident and calm you feel is partly influenced by your current circumstances. Someone taking the test during a stressful job search or a difficult period may score more Turbulent than they would at a calmer time. Research on traits like neuroticism also suggests they tend to shift gradually across adulthood, with many people becoming somewhat more emotionally stable as they get older.
If your percentage was close to 50%, a flip between A and T on a retest wouldn’t be surprising. For more on why results change, see how to tell if you’ve been mistyped.
Making Use of Your Result
Treat the fifth letter as a prompt for reflection, not a fixed label:
- If you’re Assertive, consider whether you sometimes skip preparation or brush off feedback you should take seriously.
- If you’re Turbulent, consider which worries actually help you prepare and which just cost you energy. Techniques for managing stress and self-criticism can be worth learning.
- In either case, remember that the four core letters and the A/T letter measure different things. Two INFJs, one Assertive and one Turbulent, share the same core preferences but may handle pressure very differently.
For what the four main letters describe, read our overview of Myers-Briggs personality types.