My 11 year old son is pretty smart-- he's on the honor roll at school-- but until recently he thought cats could understand English. He was very concerned that when I called one our cats a "reprehensible quadruped" it would hurt her feelings.
A childhood belief about cats and dogs

others believed things like this
- When I was little, I used to think that cats and dogs thought in English???— Isabella
- I alwaysused to think white cats were girls, and black cats were male ...— Smiley Face
- I used to believe that the cats eyes in the road...reflectors...were the eyeballs from real cats.— Liza P.
- My sister and I thought cats and dogs were the same animal, the dogs were male and the cats were female.— Paul
- Looking back at it, the belief that dogs eat cats is a pretty funny idea. I used to believe it myself.Anon
- I used to believe all dogs were male and all cats were female. I still call dogs "boy" and cats "girl." — Kelly F.