A frame at a different depth than a photograph enhances the apparent depth in the photograph

Two experiments showed that a photo frame placed at a distance from the photo itself enhances the apparent depth of contents within the photo. In Experiment 1, 32 observers rated the apparent depth of 60 successively presented photos of scenes with pictorial depth cues. In a separate block of trials, the photos were presented either with a frame in front of each photo or without a frame. Observers also assessed apparent depth of the same 60 photos by choosing the photo that had greater apparent depth when a framed and a frameless photo of the same scene were presented side by side. We found that mean depth ratings were higher for framed than for frameless photos, and framed photos were chosen more often than frameless photos. In Experiment 2, 12 observers rated the apparent depth of 20 different photos that were successively presented with or without a frame. The frame was placed in front of, at the same distance as, or behind each photo. Mean ratings for front-framed and behind-framed photos were higher than those for equidistant-framed or frameless photos, and mean ratings increased with the distance between the photo and the frame. We hypothesize that having to process the relative depth between a photo and a frame reduces the effectiveness of flatness information provided by the photo.