One of the most amazing things that living beings can do is find their way. If you think about it, that’s far from trivial. Minimally, you need a representation of the physical space around you and a representation of yourself in that space – more or less like the blue circle in Google Maps that tells you where you are relative to your surroundings. Essentially, you need a kind of Google Maps inside your head.
That may sound like science fiction, but it’s not. In 2015, neuroscientists O’Keefe, Moser, and Moser (yes, a couple) shared a Nobel Prize for figuring out how and where in the brain spatial navigation takes place. It turns out that this involves a combination of “grid cells” in the cortex and “place cells” in the hippocampus that together code your location and that of your surroundings. If you were to check out how that works (https://bit.ly/2Izn07N), you’d find that it’s not so different from Google Maps: parts of the brain basically start bleeping when you are in a particular location coded in its internal map. At least that’s how it works in rats, so assuming you’re not too different from a rodent, your internal Google Maps exists and should be located more or less in the center of your head.
It’s not too surprising we have dedicated neural representations for things like distance, time, and speed. Faithful representation of one’s position and movement would appear an evolutionary necessity for many animal species. I once saw a Dragonfly catch a Bumblebee in free flight, and the incredible spatial precision of such predators shows that miniature brain of insects must already have a pretty advanced spatial representation system. Anything phylogenetically upwards from the insects can be expected to have something like that as well.
But what about psychological dimensions like intelligence, extraversion, or agreeableness? For social species, like ours, these are almost as vital as physical dimensions of time and space. A miscalculation in areas like dominance and aggression can be pretty expensive, evolutionarily speaking. Thus, keeping track of other people’s behaviors, and especially the tendency to display these behaviors consistently, is extremely important. I think it’s likely that our brain has standard ways of doing that too.
How could that work? Judging from how we talk about these things in ordinary life, we actually seem to use a very similar system of dimensions and positions. We say that Jane is more intelligent than John, that Peter is more dominant than Mary, etc. In each of these cases, we localize people on an abstract dimension: a kind of “line”. The major current system of personality (the so-called Big Five) uses precisely such dimensions (extraversion, neuroticism, agreeableness, conscientiousness, openness) and the psychometric representation of people in these dimensions is in fact mathematically equivalent to the physical representation of objects in space.
Is that a coincidence? Maybe. But maybe not. Evolution is known for redeploying existing mechanisms for new purposes. Perhaps our assessments of intelligence and personality piggyback on representational mechanisms that were originally used for spatial localization. If so, our representations of intelligence and personality may have inherited the representational structure of location in space. That would mean that current psychometric models are actually extensions of evolutionarily ancient representational systems redeployed for psychological purposes. Mental telescopes, really.