The Myers-Briggs personality types (see, for example, Keirsey, D., & Bates, M. 1984. Please understand me. Del Mar, CA: Prometheus Nemesis..) attempt to categorize all personality types into four groups each of which has two sides by deciding which of two sides each personality leans towards from among the following groups.

• "Introvert" (I) or "Extrovert" (E)
• "Intuitive" (N) or "Sensing" (S)
• "Thinking" (T) or "Feeling" (F)
• "Judging" (J) or "Perceiving" (P)

Warning: Each term represents a specific set of characteristics and may or may not reflect the common English usage of the term.

When there are 2 choices for each of 4 categories, how many personality types are there in this model?

• 2 choices for the first category (I or E),
• 2 choices for the second category (N or S),
• 2 choices for the third category (T or F), and
• 2 choices for the fourth category (J or P).

So, there are 2*2*2*2 = 16 personality types in this model of human personality.

Here are the 16 types, with the binary numbers from 0 to 15 on the right for comparison.

• There are only 16 possible personality types in this model.
• You may not fit one of these 16. No problem.
• Insight: Not every one has your personality. Other people may see things, think, and/or approach problem solving differently than you do.

Is it reasonable for all personalities to be represented by just 16 personality types?

What is the most common personality type for programmers? Here are your choices.

• "Introvert" (I) or "Extrovert" (E)
• "Intuitive" (N) or "Sensing" (S)
• "Thinking" (T) or "Feeling" (F)
• "Judging" (J) or "Perceiving" (P)

The most common personality type for software developers is ISTJ (introversion, sensing, thinking, judging), a type that tends to be serious and quiet, practical, orderly, logical, and successful through concentration and thoroughness. McConnell, S. (1999). After the gold rush: creating a true profession of software engineering. Redmond, WA: Microsoft Press., p. 25.