Yes. Reminds me of a test I got once at a doctor's office. I was supposed to tell her all the numbers I could see on the page and the page had very faint pastel colors with numbers hidden on them. At the end of the test she was able to tell me that I was a bit dehydrated and that is why I could not see some of them - which was the case because I had been without a drink of water all day waiting in her lobby!