When Roger throws stones at Henry, what keeps him from hitting Henry? How are Roger and Henry affected by civilization?

In Chapter 4, Henry is playing on the beach, and Roger begins to throw stones in his proximity. However, Roger is careful not to aim directly at Henry and hit him. Golding describes the six-yard diameter surrounding Henry that protects him and mentions that inside of the invisible circle was a "taboo of the old life." Roger's insistence on not hitting Henry with the stones demonstrates how he has been conditioned by society not to harm others. Roger has not been on the island long enough to distance himself from the rules of society and still believes that it is wrong to hit others with stones. While Roger is throwing stones at Henry, Henry continues to play on the beach and does not worry about being hit. Even Henry has been conditioned by society and takes it for granted that Roger will not aim directly at him. Henry finds it funny that Roger is throwing stones close to him and is not afraid of being hit by them. Both boys demonstrate how society's rules and regulations have affected their behavior.