The phenomenon of the ‘third effect’ intrigues me. Two images side by side generate meaning not turned out by either image alone, and the juxtaposition of image and text shares this generative potential. How do captions (particularly those which are partially interpretive) influence the viewer’s understanding of photographs, and what role do captions or descriptions play in shaping the meaning or message of photographs? Why does the bringing together of pictures and words side by side generate meanings not produced by either thing on its own, and in what way does this interplay question the usual relationship between vision and knowledge (natural, visual, cultural, verbally transmitted, ideological)?