Phrenology is bumps on the head right? I think hook nose would be physiognomy. But yes, the idea was that your behavior was due to your brain and your brain was composed of many different parts that each controlled different propensities or abilities. Then it was just a matter of identifying where those propensities lived, in relation to the head and then you could feel for the differences from person to person across the surface of the head. From the naive viewpoint it is plausible, oh, you say the back right section of my head, above the ear is a bit larger so the self-control portion of my brain is well developed? I've always thought so!
Setting aside the marshmallow test, you can easily see how scientific theories about this sort of thing, both right and wrong, easily integrate.