If it does not, the photograph is unsuitable. His finger is on the shutter button and his energy will be used to push it, but the push itself is triggered at some particular point in his interaction with the subject. Even if his subject is a landscape, he interacts with it. When certain of the arrangements among photographer, subject, viewer and photograph are understood and specified, photography can be used to investigate the behavior of any of the three persons involved. And since we are interested in the relations along the three entities, we never need to make a priori assumptions about the photograph itself.
Human behavior is patterns of patterns of patterns, decreasing in scope beyond normal social seeing.
In the still photograph, we can find relations frozen that are, in life, too fleeting for our eyes. Others have attempted to avoid the problem by hiding the camera. Quite apart from ethical objections, hiding cameras rarely solves the contamination problem because there is usually someone who is privy to the hidden camera and who, because of his special knowledge, behaves in some small way that others cannot account for. Then this behavior contaminates the situation. In a similar fashion, an African might provide the anthropologist with a more precisely structured and accessible interpretation of his culture through the photographs he could take of it than through the words he may speak about it or, perhaps, even through the inferences the observer may make from his behavior.