Lamps Used in Study (IMAGE) Smithsonian National Zoological Park Caption The three lamps used in the study: from top to bottom a LED 3000k lamp with a yellow filter, with no filter, and with an amber filter. Credit Jessica Deichmann/Smithsonian 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.