Back to the topic, I've noticed the difference you mentioned; especially in young infants. I've stared at young orang in zoos, and once or twice you catch their eyes and get into a bit of a staring contest. I swear you can almost see them think. Of course you get a bit of that with chimps, but I noticed a difference in scale. It's small, but it's there.
Again, totally unscientific. I could well have imagined it all.