Franz Gall popularized , which argued that criminality was marked by brain abnormalities that could be identified by feeling the skull.

Phrenology.

Explanation:

Franz Joseph Gall was a German physician whose work consists of anatomical comparison especially of brain matter between humans and animals. His works revolve around the science of the mind, the differences and similarities of brains among the various age groups, and also among animals and man.

The concept of phrenology is a pseudoscientific approach that requires the measuring of bumps in the brain to predict mental traits. This allows for the prediction of human personality traits based on the contours of the person's brain and skull. And according to Gall, he believes that criminality was marked by a person's brain abnormality, which is measured ad felt from a person's skull.