Most people appreciate a good optical illusion, but they can be frustrating at times as well. That is especially true if you are trying to look beyond the illusion and see what is really in front of you. There are certain aspects about your vision and your brain that will often keep you from really seeing the reality of the situation because of your perspective or other factors.
These types of phenomena are rather interesting to study. It is always a lot of fun to look at the optical illusion itself and see how they can trick the eyes, but understanding what is behind it is also quite enjoyable. Some research has suggested that what we see is compiled in the brain from sensory input that comes from the eyes. Depending upon what input is given, it may use a different part of the brain, and that is why some of these optical illusions can fool you.
In other cases, it may have to do with you and your life experiences. For example, the optical illusion in this video in which you are either seeing a duck or a man may be answered differently, depending upon who you are and even when you see it.