In The Call of the Wild, the most obvious technique London uses to manipulate readers is to anthropomorphize the dogs in the story. Ironically, he gives Buck a human-like personality and motivations as he sheds all traces of civilization to return to his natural state as an animal in the wild. Take, for example, the passage where Buck learns about the violent kill-or-be-killed ways of living in the wilderness:
[Buck] had learned well the law of club and fang, and he never forewent an advantage or drew back from a foe he had started on the way to Death. He had lessoned from Spitz, and from the chief fighting dogs of the police and mail, and knew there was no middle course. He must master or be mastered; while to show mercy was a weakness. Mercy did not exist in the primordial life. It was misunderstood for fear, and such misunderstandings made for death. Kill or be killed, eat or be eaten, was the law.
These are very human ways of expressing such ideas and a great example of how Buck is anthropomorphized.
London also uses vivid imagery to show the terror and majesty of the wilderness, reflecting Buck's changing feelings regarding it. At first, he is scared of what lies beyond civilization, but soon he feels its beauty and the freedom it promises enticing him. Check out the following passage describing Buck as he is in the wilderness at the end of the novel:
But he is not always alone. When the long winter nights come on and the wolves follow their meat into the lower valleys, he may be seen running at the head of the pack through the pale moonlight or glimmering borealis, leaping gigantic above his fellows, his great throat a-bellow as he sings a song of the younger world, which is the song of the pack.
London's language here is very lovely, showing Buck's fulfillment in the beauty of the wild. Because London has described things such as pale moonlight and the glimmering borealis, we get a sense of the wild as beautiful and, furthermore, a sense that it is good for Buck to be there and not pampered in a human household.