Golding's clever characterization of the boys through dialogue constantly reminds the reader that the characters are young children. At the beginning of the novel, the boys act more like children, because their actions on the island are much more childlike and innocent. For example, when Ralph finds out that there are no grown ups on the island, he stands on his head to convey his excitement. However, as the novel progresses and the tension on the island builds, the reader gets caught up in the action, and it becomes easier to forget that the main characters are children.
Golding cleverly uses the boys' dialogue to reinforce the fact that these are only children. In one of the more tense scenes in the novel, Jack breaks away from Ralph's tribe after a bitter argument, claiming:
"I'm not going to play any longer. Not with you" (117).
This quote from Jack immediately emphasizes his childishness and immaturity. It's a classic kids' retort of 'I'm taking my toys and going home!' This darkly humorous moment completely brings readers back down to reality, advising them that despite all the tension, political machinations, and very real danger, that Jack and Ralph are only boys after all.
At the end of the book Ralph bursts into tears in front of the Naval officer. This reminds use that they are actually only young boys and there is a a sudden realisation of how sad the story really is.
This is also the only moment that Ralph cries in the whole book.
Another indication is that Jack doesn't argue with who is leader because he realises he is going to get in trouble and almost doesn't want to go back and suffer the consequences a very childish thing to do.