For many years, it was thought that this type of reaction to their social environment indicated that autistic individuals did not like or were fearful of people. Another theory, which is based on interviews with autistic adults, suggests that the problem may be due to hypersensitivity to certain sensory stimuli. For example, some state that a parent's voice hurt their ears; some describe the smell of their parents' perfume or cologne as offensive, and others describe pain when being touched or held.