After Nate was born 4 years ago, a coworker of mine came to visit when he was around a month or so old. I must have told him something like "he slept n hours last night and during the day we had done XY and Z with him so we're doing XY and Z with him today so that he'll sleep n hours again!" And he laughed and told me about Skinner's "superstitious pigeons." The pigeons were fed at regular intervals regardless of their behavior. Nevertheless, they associated whatever they did right before the food came as having caused the food to arrive, thus becoming "superstitious" and repeating that behavior frequently in hopes that food would come. He joked that parents are the same way.
This time around I am trying not to be a superstitious parent. But sometimes I can't avoid it. It's tough when you want a certain behavior to repeat. I have seen over the past week that it doesn't really matter what Jack does during the day, he's still going to sleep 6-8 hours for his first stretch. This is a good thing.
Of course, there are certainly some things that will affect the baby. :) When you smile and make funny faces, he will smile back. We've also discovered that when I drink caffeine, he spits up a ton. When I don't, he barely spits up at all. Nate was a big spit-upper so we assumed Jack was another "happy spitter." That means that the spit up is not due to reflux or colic, and they aren't in any discomfort when they spit up. But Jack was spitting up so much that he'd actually wake himself up because he'd be soaked around his neck and his head would be in a puddle. I was doing all the things "they" suggest -- holding him upright for 20-30 minutes after feedings, raising one end of his crib a little (this also helped with congestion when he had a cold) -- but he was still spitting up immense amounts. I was getting ready to try cutting dairy thinking maybe he was sensitive to it (though he didn't really have any of the symptoms of a dairy allergy besides the lots of spitting up). Nothing I read online suggests that caffeine is a cause of spitting. Someone on a moms' list I read made a comment about having cut out caffeine and I decided to give it a try. It was easier than cutting out dairy. And it seems to have worked. No superstitious parent behavior here. Just a happy baby who isn't spitting up constantly.