The main, or central, idea of the passage is Prosopagnosia is a sometimes severe disorder that causes people to have difficulty recognizing faces. How does the detail in bold develop the main idea?
While everyone has occasional difficulty recognizing others, people with prosopagnosia experience this problem to a much greater extent. Prosopagnosia, a term derived from the Greek words for "face" and "lack of knowledge," refers to a neurological disorder that impairs a person's ability to recognize faces. People with severe cases of the disorder may even have difficulty recognizing their own family members. The current understanding of prosopagnosia is quite limited, although the condition is thought to be related to a problem in a fold of the brain called the right fusiform gyrus. By conducting research on people with face blindness, neuroscientists hope to learn more about its causes and develop possible treatments. For now, people who are face blind must rely on alternative techniques to identify others. They may recognize people by their voices, clothing, or hairstyles, or they may infer someone's identity because they routinely encounter the individual in a particular setting.