When red lights look yellow.

  title={When red lights look yellow.},
  author={Joanne M. Wood and David A. Atchison and Alex Chaparro},
  journal={Investigative ophthalmology & visual science},
  volume={46 11},
PURPOSE Red signals are typically used to signify danger. This study was conducted to investigate a situation identified by train drivers in which red signals appear yellow when viewed at long distances (approximately 900 m) through progressive-addition lenses. METHODS A laboratory study was conducted to investigate the effects of defocus, target size, ambient illumination, and surround characteristics on the extent of the color misperception of train signals by nine visually normal… CONTINUE READING