affected by familiarity with similar puzzles, viewing conditions, image quality, screen size, attention and numerous other situational factors.
Experience can make a particularly noticeable difference. Someone who frequently solves optical illusions may already know to examine negative space, unusual shadows and larger patterns instead of concentrating only on obvious objects. A first-time viewer may understandably approach the image like an ordinary photograph and focus primarily on the deer. The experienced viewer is not necessarily seeing better in a general sense. They may simply have learned a search strategy particularly useful
