Vision Test (IMAGE) University of Cincinnati Caption UC biologist John Layne explains how they use a looming stimulus to determine if fiddler crabs can detect subtle differences in color. A stripped-down LCD projects a video image of a looming ball that is depicted in color via adjustable light-emitting diodes. Credit Andrew Higley/UC Creative Services Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.