Freud and his theory will be discussed in more detail in the unit on personality. It is sufficient for our present purposes to note that theories of child development which are used by clinicians in the treatment of personality disorders take the concept of critical or sensitive periods very seriously. Dogs that do not associate with humans between 3 and 13 weeks of age cannot be made pets. Dogs salivate in anticipation of food. Dogs can be trained to sit, lie down, beg and heel if training is consistent and firm.
Dogs can become effective sentries, although some breeds are better sentries than others.
The behavior of humans is quite different from the behavior of lower animals. Man's ability to communicate through language both verbally and in written form enables him to be much more flexible than lower animals. Imprinting is a process in which an inborn behavior pattern becomes strongly associated with a releasing stimulus. Schein found that when no humans were present, all six courted other turkeys. When no other turkeys were present, they all courted humans.