I wonder how much this recognition effect varies by background. Where I grew up, two out of three houses had a dog. I've never met someone from my side of town who was scared of dogs in general. In other locations I've seen multiple households running back inside as a dog I knew was friendly was walked by.

The kids in the sample were probably all from the same area and economic class, and so would likely have similar backgrounds. Were the adults the usual 10 college students?