okapi says

Michael Ashley, the media specialist for the BACH team from 1998, wrote his PhD dissertation at UC Berkeley on archaeology and vision (completed in 2003), focusing on visual perception in the past and present at Çatalhöyük. In 2002, Michael carried out a series of tests on the ability of archaeologists to see contrasts in soil colors in different excavation contexts. Using a special sheet designed to test contrast vision, he tested a large number of Çatalhöyük team members in a variety of places. Here he has set up his chart prior to testing the archaeologists working at the highest point of the East Mound, where the team from Poznan, Poland, was excavating without benefit of shelter or shade.