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Giving people unlimited time can make the activity more relaxed and enjoyable. Instead of racing against a timer, viewers can experiment with different strategies. They can move closer or farther away, reduce the image size, rotate it or temporarily cover the deer. Each technique provides another way to investigate how the visual organization changes.
For parents or teachers using similar puzzles recreationally, the discussion after solving them can be more interesting than simply asking who finished first. Participants can explain what distracted them, which clue finally helped and how the scene looked after recognition. This encourages observation and conversation without pretending that the puzzle provides a formal measure of cognitive ability.
The experience can also demonstrate why people sometimes disagree about what is obvious. Once one person has recognized the face, they may genuinely find it difficult to understand how someone else cannot see it. Their perception has already reorganized the relevant shapes into a meaningful object. The second viewer is still seeing those same elements primarily as pieces of the forest.
Giving a direct answer immediately can therefore produce an almost comical reaction. The viewer may go from seeing nothing unusual to wondering how the face was ever difficult to notice. This sudden sense of obviousness is a consequence of recognition. Knowing what to look for changes which parts of the image receive attention and how they are grouped.
The effect can remain even hours or days later. If the same viewer encounters the picture again, the hidden face may appear almost instantly. Memory now provides a powerful guide to attention. The puzzle that originally required several minutes can become effortless because the viewer no longer needs to discover the alternative interpretation.