Ryan made excellent points about a one-year old's comprehension and interpretation of circumcision (or of anything).
Studies have show that boys do not become aware of their penis as the central part of their manhood until they reach nearly age 5.
A psychologist wrote a book on the study of psychological impotence and one of its chief causes. A study of those victims found to have nothing physically wrong with their sexual anatomy but who were nonetheless quite impotent found one thing they all had in common. They had been circumcised when they were about age 5.
It seems that they had become aware of their penises and their manhoods, but were not old enough yet to recognize that the foreskin was not an essential functional part of the penis.