Scientists estimate that about 4% of the population experience some form of synesthesia (e.g., different senses blend in a variety of ways). These individuals are known as synesthetes. The phenomenon of synesthesia probably stems from normal cognitive development during gestation and early childhood. Large numbers of neural connections are formed as the brain grows. Many of these connections are later pruned away. Synesthesia may arise from an incomplete shedding of some of these connections. There are different types of synesthesia. When mirror-touch synesthesia was identified (e.g., people feel a sensation on their own body when they observe someone else being touched) some synesthetes were surprised to realize that experiencing this type of disembodied contact is considered unusual. A study at University College London found that mirror-touch synesthetes showed higher capacities for emotional empathy than others did.