I have distinct memories of seeing ghosts when I was a very young child (2-4yo). Once I realized no one else could see them, I tended to keep sight of them to myself but would secretly wave or acknowledge them. Usually, they were glad to be seen and were kind in return. Sometimes they just wandered away.
There was an instance when my mother was pushing the stroller I was in through the mall. She stopped to talk to a friend and I noticed a teen-aged girl ghost. She seemed very confused. When she saw me, though, she smiled and waved. I waved back. She made funny faces. I laughed. I made funny faces back. She smiled. Just then, my mother's friends exclaimed, "you have such a happy baby!" and stuck her head in the stroller. I recoiled at the shock.. after seeing the ghost girl (so full of life), this tired woman seemed to be more dead, a zombie. I shut my eyes and when I dared to look again, the girl was gone and the lady seemed, well, at least alive.
I couldn't appreciate the irony then, of course.
So few of the ghosts were happy; they seemed weary but couldn't or wouldn't move on. In particular, the Old Man. But that's a story for another post.