Teen study finds that gullibility increases with age

Taylor Swift in "Tim McGraw," which she released at age sixteen but that refers back to a conversation that occurred when she was thirteen*:

You said the way my blue eyes shined
Put those Georgia stars to shame that night
I said, "That's a lie"

Taylor Swift in "Fifteen" (recorded when she was eighteen):

'Cause when you're fifteen
And somebody tells you they love you
You're gonna believe them

*EDIT: Turns out that she wrote "Tim McGraw" at fifteen and was projecting three years into the future about what it would be like to look back, so the convo took place when she was fifteen. And for all I know that interchange is fiction, though the song was inspired by a real relationship.