Another variable that might influence IV and DV is the amount of interaction a baby has with strangers. A baby might have a very secure base, but if he does not get a lot of opportunities to practice interacting with strangers, his comfort level levels with strangers might not be as high as a baby who has had more interactions with strangers. Likewise, a baby who doesn't have a high level of attachment but who interacts with many strangers might indeed have higher well being later in life.
I actually really like this idea. I know that this seems to be the case for many Chinese boys growing up in China. They seem to be far more shy compared to boys of other nationalities simply because they don't get exposure to people and the world around them.
