What does phrenology claim about bumps on the skull?

Phrenology asserts that the shape and bumps on an individual's skull can provide insights into their mental abilities and character traits. This theory, developed in the early 19th century by Franz Joseph Gall, posits that different parts of the brain are responsible for different faculties or traits, and that the overdevelopment or underdevelopment of these areas manifests as physical bumps on the skull. This connection suggests that by examining these bumps, one could infer personality characteristics and cognitive capabilities.

While there are references to cognitive abilities and their potential influences, the primary claim of phrenology centers around the idea of revealing mental abilities or traits rather than just influencing them. The other options, such as linking bumps to behavioral disorders or impacting sensory processing, do not align with the fundamental tenet of phrenology, which is the relationship between cranial features and personality, rather than being solely focused on disorders or sensory functions.