What is the term for "What has been seen cannot be unseen" in cognitive sciences? During a discussion with my officemate I told him that I read somewhere that the gas pillar in Carina nebula looks like a cat punching the dog; ever since then, every time my wallpaper slideshow switches to this wallpaper, "cat vs dog" is the first thing that comes to my mind. We were curious whether there is some dedicated terminology for this. 

I learned via Google that this is a meme called "What has been seen cannot be unseen", I wonder what is the term for this phenomenon in cognitive science? Like a memory bias during the perception of something? Or it is that people tend to visualize some new concept/picture/term as something they are more familiar with subconsciously?
The most relevant term would be Ironic Processing.


  Ironic processing is the psychological process whereby an individual's deliberate attempts to suppress or avoid certain thoughts (thought suppression) render those thoughts more persistent.


This is a result of a failure of Thought Suppression or more generally Motivated Forgetting. It appears Thought Suppression doesn't work well and generally the attempt to not think about X results in a sudden increase of thoughts about X. 

Since you have a sudden increase of thoughts about the "suppressed" thought, you're strengthening retrieval of it, and you might even be conditioning that thought with the reason you don't want to remember it.