Given its historical interest in perception, cognition, and motor function, there is much that psychology can contribute to the study of ballot design. There are two main problems to consider when designing ballots. For one, ballots should be functional. People should be able to use them with ease. This issue is of particular relevance for elderly voters, who may suffer from cognitive, perceptual, or physical difficulties. In a 2007 study by Tiffany Jastrzembski and Neil Charness, elderly voters were shown electronic voting machines that differed in two ways. Votes were entered via touch screen or key pad, and races were presented either one at a time or all at once. This resulted in four different combinations of ballot design. Elderly voters performed best on the combination of touch screen ballots with races presented one at a time. Additionally, ballot design should not favor one candidate over the other. For example, in a 1998 study by Joanne Miller and John Krosnick, name order was found to significantly affect voter choice in forty-eight percent of 118 races in the 1992 Ohio state elections. On average, the candidate on the top of the list received 2.5 percent more votes than the candidates listed further down the ballot. While that may not seem like a large margin, it is enough to win an election.