What do you see in the above picture? A rabbit? A duck?
This image shows a phenomenon first described by an American psychologist, Joseph Jastrow, in 1899 and tells us a few things about the brain’s way of processing visual information.
Firstly, this picture is neither a duck nor a rabbit. However, our brain tries to match it to what it has seen in the past, and in that process (for example) it decides it must be a rabbit. Then when the same picture is presented, it decides it must be a duck, because the picture appears to match both figures and the brain randomly decides it can only be one of them.
This experiment proves that the human brain does not simply record visual information on to film (memory), but instead processes it first then records it. This is the reason we see UFOs in clouds, the face of the Virgin Mary on burnt toast or a rabbit on the moon. This phenomenon is called pareidolia, when the brain gives a meaning to what is actually a random visual stimuli. Due to this, we cannot totally trust what we see.
Also, this picture teaches us a valuable lesson regarding our perception. From one point of view it is a rabbit, but from another it is a duck. This kind of scenario is seen countless times in life, such as a song you hated that suddenly sounds great, or a guy you once thought was a tool appearing wonderful all of a sudden, or a girl you never even considered becoming attractive one day.
Like this, perception can not only be affected by optimism and pessimism, but even small things like emotions or random events.