The series of "Missing Object"s exercises are provided to improve your visual memory. In the next couple of posts, you would be on this matter. Then, you should do this in your normal life; e.g. when doing a window shop you must remember more items at each store. To be more efficient on this, you may have a quick view on the stores windows, close your eyes for a second (something like a slow blink) and imagine the windows objects in your head; the clearer image in your head the better. Keep doing this practice until you could have a right memory to remember 40 items in a single glance; it seems too hard but you should believe that "Übung macht den Meister"; i.e., "practice makes the master".
OK, now, look at this picture for 15 seconds:
The following picture is a copy of the previous one; however, an object is missing. Can you remember which one?
If you cannot remember it then try this exercise again! It might be a little hard as you may not know a name or an index for each object! This is not a problem, but it is a good practice for your brain
to visually remember!