Two Types of Vision (IMAGE) University of Exeter Caption A nightjar as seen by a trichromat (left) and a dichromat (right). Credit University of Exeter Usage Restrictions Only for use with reports of this research 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.