For those unfamiliar with them, Jung’s cognitive functions (used in the MBTI) are: thinking, feeling, intuition and sensing. Each of them can be either extroverted or introverted. Let’s try to associate each one of them with the characters.
Anger is motivated by order, and gets irritated when something isn’t as it should or doesn’t turn out the way it should, which makes it pretty similar to the thinking cognitive functions. Extroverted thinking would be triggered by external disorder while introverted thinking by internal disorder.
Fear is constantly imagining what could go wrong and how, kinda similar to the functions of extroverted and introverted intuition, albeit he leans way more towards negative possibilities.
Disgust reacts instinctively and spontaneously to people and stuff, somewhat similar to the feeling functions.
Joy is motivated by pleasure and by the satisfaction that comes from sensory stimuli, very much like the extroverted sensing. Introverted feeling probably would result in a Joy oriented to memories rather than the outside world.
The extraversion-introversion dimension could very well be the emotions’ tendency to either turn attention to the screen or to the islands of personality and memories.
There is no cognitive function left for Sadness. But I think she can take on the role of a personality trait called neuroticism, which can be thought of as the emotional susceptibility of an individual to external influences.
Although neuroticism is not included in the usual MBTI, it is one of the Big Five’s traits, a psychological model widely accepted by the scientific community. And in addition to that, these traits share a lot of similarities with Jungian cognitive functions. To the point that the 16personalities online test uses criteria typical of the big five to determine the personality.
The reason 16Personalities test often makes mistakes is in my opinion due to the fact that the Big five’s traits are measured on a continuous scale while the MBTI is more “binary” (S / N, T / F etc.) therefore some information is lost during the transition from one system to another, and that leads to errors. And the fifth letter that the 16personalities test adds is also just a measure of neuroticism (A / T).