After recording brain responses to the black and white objects, the scientists presented real colors to their subjects, in the shape of yellow, green, red and blue rings. This allowed them to record the activity of the brain as it responded to different, real colors.
It turned out that the mere sight of black-and-white photos automatically elicited brain activity patterns that specifically encoded colors. These activity patterns corresponded to those that were elicited when the observers viewed real color stimuli. These patterns encoded the typical color of the respective object seen, even though it was presented in black and white. The typical colors of the presented objects could therefore be determined from the brain's activity, even though they were shown without color.
Culture Magazine
When we look at black and white photographs, the brain interpolates color:
