In Peter Pan by J. M. Barrie, Peter is a perennial child. He will never grow up, and he does not want to grow up. Thus, like most children, he is somewhat self-centered and has a relatively limited attention span. He is the center of his own universe, as are many children. Because Peter is preoccupied with himself and, to a lesser degree, with the Lost Boys, he does not notice as much of what is taking place around him or the actions or feelings of those around him as Wendy does.
Peter has a child’s view of life. He wants to play, be happy, and have Wendy tell him and the Lost Boys bedtime stories. For instance, Peter’s way of feeding the boys was
to pursue birds who had food in their mouths suitable for humans and snatch it from them… But Wendy noticed with gentle concern that Peter did not seem to know that this was rather an odd way of getting your bread and butter, nor even that there are other ways.
Peter does not notice, because he wants to have fun, just as any other child does.
Wendy and her brothers return home after being in Neverland with Peter and the Lost Boys, but she and Peter agree that he will come back for them. The author says,
Peter came for her at the end of the first year. She flew away with Peter in the frock she had woven from leaves and berries in the Neverland, and her one fear was that he might notice how short it had become; but he never noticed, he had so much to say about himself.
Thus, Peter “never noticed,” and the reason, according to the story, is because “he had so much to say about himself.” Like most children, Peter is eager to speak about himself and be the center of attention. That limits the amount of time or attention span that he can devote to noticing much about others.
At the end of the story, Peter comes for Wendy again years later. She is an adult, married and with a child of her own, but Peter does not notice that Wendy has grown up. Peter pays attention only to what interests him.
“Hullo, Wendy,” he said, not noticing any difference, for he was thinking chiefly of himself; and in the dim light her white dress might have been the nightgown in which he had seen her first.