Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Photograph of stimuli under experimental presentation. The two compartments each contain a pair of objects that are illuminated independently by light sources that differ in intensity by a factor of four. All four objects have the same reflectance contrast, but one differs in mean reflectance.
