Tiny writing ... is it a sign of deep concentration? A preference for using fine motor skills? A combo, or something else? Whatever. Let's see which types are most inclined to do it (as if this were actually scientific!)
Doesn't have to be writing this way all the time - now and then is good enough.
By "tiny," let's estimate the middle zone (e.g., the span of an "e") to be a maximum of ... ohh ... hmm, let's say 2mm high.