<qa>  What is the purpose of the study?Blind and sighted people 18 years of age and older are eligible for this study. Healthy, sighted individuals may participate in Part 1 of the study, which is designed to find appropriate words to use in tests for Part 2 of the study. Part 2 will include sighted people and blind people. It will examine whether the visual brain in blind people is processing mnemonic information in a way that helps with day-to-day memory functions. Blind participants in this study must have lost their sight by age 4. Candidates will be screened with a medical interview and examination and a brief test of short-term and long-term verbal memory. Sighted patients will also be tested for visual memory and for handedness. 