75-year-old Muriel Exson and her 71-year-old sister Pauline Davis are helping researchers piece together a complex puzzle. "I haven't found a piece yet," said Muriel. A puzzle that will reveal what normal memory test results are for African Americans. "So when we get another person who comes in the office with a memory problem and we test them we can compare them to a like group of people," said Dr. Floyd Willis. Keeping in mind that African Americans come from different groups and backgrounds. Memory tests are based on answers from hundreds of elderly people, many of whom do not share the same life experiences as older Africans. Our backgrounds shape our perceptions, even the words we use to describe things. For example, you might call an object a hammock. But there's a group of folks who grew up calling it a hassock. For tests to truly reflect memory, they must consider these types of differences. "We've got to know exactly or as early as possible when the memory is beginning to fade," said Willis. Solving the puzzle early and accurately is critical.