Phrenology (from Greek: φρήν, phrēn, "mind"; and λόγος, logos, "knowledge") is a defunct field of study, once considered a science, by which the personality traits of a person were determined by "reading" bumps and fissures in the skull.
What phrenology did is to try to examine humans’ skull shapes and to try to make conclusions about what their personality were like. The argument was that there should be relationship between brain structures in different parts of the brain and different psychological attributes. Phrenologists believed that each bump or indentation in a patient's skull corresponded to his "brain map". An enlarged bump meant that the patient utilized that particular "organ" extensively.
The main problem with this theory was that there is no connections, what so ever, between bumps on a head and underling brain structure, unless of course you were involved in some kind of accident and you have your skull smashed and there was a connection. Beyond that there is no connection in normal people, what so ever.
This kind of theory in technical terms is known as “crappy”. There are many such theories in social sciences. There are certainly has been many in psychology and they are not only limited to the 19th century.
The question you may raise then is:
If the theory can take us that far; if the theory can be that wrong why would we simply do without theory at all? Why would we simply stick to the facts?
The reason that we don’t is that we can’t. We are cognitively or psychologically unable to see things or to understand things without imposing some kind of order on ourselves. We never see just facts out there. We are always somehow imposing an order on data that we see. This is true not only for scientific theory but it is also true for minor perceptual experience.
If you look at this picture, what does it looks like to you? For example, look at the middle parts of it of the picture. What do you see?
