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David L. Kendall's avatar

Hollis, spurred on by your excellent essay, I prompted my Ai with this:

I found the MBTI interesting and useful for certain purposes. Couldn't the MBTI be constructed in vector space instead of having just four categories and 16 summary boxes, thereby rendering it more interesting for psychological personality research?

The Ai response:

Yes, and in fact that move eliminates one of the strongest objections to MBTI. Once you stop forcing people into 16 boxes, the underlying four MBTI scales can be treated as continuous coordinates.

Imagine a person represented not as INTP, but as a vector:

p=(E/I,  S/N,  T/F,  J/P)\mathbf{p}=(E/I,\;S/N,\;T/F,\;J/P)

with each coordinate ranging, say, from −1 to +1. Someone might therefore be

p=(−.82,  +.15,  −.61,  +.07)\mathbf{p}=(-.82,\;+.15,\;-.61,\;+.07)

That says considerably more than a four-letter label. The person is strongly toward one pole on dimensions 1 and 3 but essentially near the middle on dimensions 2 and 4. The familiar MBTI "type" would simply identify the orthant of four-dimensional space containing that point. The 16 types are just the 24=162^4=16 regions produced by cutting four continuous dimensions at zero.

And now something interesting happens: the notorious MBTI boundary problem largely disappears. Two people scoring −.01 and +.01 on a dimension are recognized as virtually identical rather than being declared different "types."

But would this make MBTI scientifically preferable to the Big Five?

Not automatically. It would make it much more defensible, but we'd still have to ask whether those four axes are the best dimensions along which to describe personality.

The Big Five is already doing essentially what you're proposing. A person's Big Five scores constitute a vector in five-dimensional personality space:

B=(O,C,E,A,N)\mathbf{B}=(O,C,E,A,N)

The scientific question therefore becomes not 4 dimensions versus 16 boxes, but:

Which coordinate system best captures psychologically meaningful variation among people?

That's an empirical question.

And MBTI actually fares better under that interpretation than its reputation sometimes suggests. Several MBTI dimensions map substantially onto Big Five dimensions. E–I corresponds strongly to Extraversion, while S–N relates substantially to Openness. Some aspects of T–F overlap with Agreeableness, and J–P has relationships with Conscientiousness. The mapping isn't perfect, however.

There is also something about MBTI that I suspect explains why you found it useful: its axes are intuitively interpretable as cognitive or behavioral contrasts. "Do I tend to rely on concrete information or abstractions?" and "Do I tend to make decisions through impersonal analysis or interpersonal considerations?" can sometimes be more interesting questions than simply learning that someone scores 73 on Agreeableness.

Where your idea gets especially interesting

You don't have to stop at four dimensions—or five.

Suppose we retained dozens or hundreds of psychologically meaningful dimensions and represented an individual as

x=(x1,x2,x3,…,xn).\mathbf{x}=(x_1,x_2,x_3,\ldots,x_n).

Now personality becomes a point in a high-dimensional semantic space. We can calculate distances between individuals, identify clusters, examine trajectories through time, and ask whether particular regions predict behavior.

That gets remarkably close to Robbins's argument in the essay you just sent me. Modern computational methods—and especially language models—remove much of the historical necessity for reducing personality to four or five numbers.

I

nstead of asking:

"Which of 16 kinds of person is Jack?"

or even:

"Where is Jack on five traits?"

we could ask:

"Where does this individual lie in a 200-dimensional behavioral/linguistic space, and which dimensions actually predict behavior?"

That strikes me as a much richer research program.

There's also a wonderful irony here. MBTI's biggest conceptual mistake may not have been its four dimensions at all. It may simply have been throwing away most of the information in those dimensions by converting continuous scores into letters.

And that is an economist's complaint if I've ever heard one: why take continuous data and voluntarily turn it into a dummy variable?

M Ivonne Wallace Fuentes's avatar

Thank you for this fascinating history of the Big Five and the contingencies of how that came to be canonized as *the* tool we have to understand and codify human personality and how 1940s era statistical tools erased relational traits, giving us a framework that can only provide a stunted and incomplete understanding of what human personality actually is. I read this right after the “What a Time to be an Agent” piece and found the argument really thought provoking, although I’m not versed enough in linguistics to squeeze all the juice out of this lemon — my own field is history. As I read your work, it proposes that the tools and philosophies of literature inform (and perhaps offer the only way forward) to creating stable personalities in LLMs because of how it can actually deal with the human relational connections that undergrid personality that current ML training practices will inherently average away in the training corpus. It’s such an ambitious project, creating and designing something like a stable personality that persists through time and through the challenge of constant interaction with users. In my own usage of these tools (Cowork, not Code, lol) I’ve found that constraining the tool through iterative and evolving global instructions to map out a preferred relational texture is giving me a model with a stable-enough personality for the kind of professional collaboration I want it to do. Of course, it’s user directed — which for me is a feature, not a bug— and certainly not a “caring personality” ready to deal with our elders, or anything like that. I just posted about this relational constraint today: [https://mivonnewf.substack.com/p/the-dialogic-mirror-cognitive-fitness?r=3p2zgl]. Thanks for so much to think about.

Also, the Borges load in the corpus must be a real thing — it pops up a lot in my own convos with Claude, although since I am a Latin Americanist, I attributed it in part to Claude refracting my own interests and influences back to me, marginalia style.

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