Powells.com Interviews - Mary Roach:
Dave: In a footnote, you mention two separate occasions when you were moved to conduct experiments about the curiosity of cows. Specifically, you shouted at cows in a field and then lied down in the grass.

Roach: Yes!

Dave: Why?

Roach: When I was in college, I got into a late-night argument with somebody about whether cows are curious. He said to me, this guy Brian, that if you go out in a field and do this they'll come over. I didn't believe him, so the next chance I got I went out into a pasture and the cows were a couple football fields away; they were pretty far away. I shouted, and they looked. Then I lay down, and they literally galloped over to me and formed a ring around me.
I did it in Ireland and I've done it in California. Both times, the cows came over. Cows are curious.

Dave: Were you scared at all the first time when the galloping started?

Roach: A little nervous when they came thundering over, but I assumed they would stop. Supposedly, it's like if a buffalo herd comes charging at you, you're supposed to just put your hand out and they'll go around you. I don't really want to give that one a whirl, though.