Follow the instructions for the first image. Note: because your display might render these smaller/larger than mine, you will need to adjust how far your head is from the monitor. What I do is move my laptop/phone closer/further until the blindspot effect kicks in.
Now, try the following as well
- and elephant should disappear at some distance, depending on which eye you have closed.
- or X should disappear at some distance.
- should disappear, or, yellow circle should look red!
- and circle disappear