What is the phenomenon called, when things start resembling what you are thinking about?

like when Tom is hungry he sees jerry as a hot dog. When you are searching for something every other thing appears that it is the very thing you are searching for.

EDIT:

So as suggested in the comment here is what I want exactly:

I want to give title to this event which happened: On 31st December as I looked into an old message which my friend had sent me, I got surprised as to when he sent me a Happy New Year message, when suddenly I realized that it was written "Happy to Hear"

Solution 1:

I'm not a psychologist or a psychiatrist, but this sounds like it fits the term perceptual distortion, particularly the variant termed self-fulfilling prophesy on slide 21 in the link.

From montofacto.com:

Perceptual distortion: Lack of correspondence between the way a stimulus is commonly perceived and the way an individual perceives it under given conditions.

Solution 2:

This is called a mirage. merriam-webster

an optical effect that is sometimes seen at sea, in the desert, or over a hot pavement, that may have the appearance of a pool of water or a mirror in which distant objects are seen inverted