Correction:
“A 2011 article in Pediatrics magazine found that children who had been asked to taste a “new” cereal reported liking the same cereal more if there WAS a popular character depicted on the box.”
Now, come on, today’s writers can’t be expected to understand subject/verb agreement, can they?
In this case, the writer is suggesting that IF there WERE a character on a box of cereal, children would be more likely to like it.
I don't say "If I was President, I would..." The proper form is "If I were President, I would..."
-PJ