Age (weeks) 3 - 14. Socialization Period. If socialized later than 14 weeks, (or between 12 - 14 weeks in some dogs) shyness or agressiveness may dominate behavior.
Age (weeks) 6 - 8. Optimum Socialization. If socialized earlier, shyness often develops, along with overdependence onowner, which maylead to overprotectiveness.
Age (weeks) 8 - 10. Fear Imprint. Traumatic, fear-producing experiences may be permanently impressed causing defensive reactions in some circumstances.
Age (weeks) 12 - 14. Puberty Onset. Meaningful sexual mounting often occurs. Males display erections.
Age (weeks) 18 - 40. Protective-Aggressive. Barking at strangers and other territorial and social group protective tendences may occur. Leglifting may begin in males.
Age (weeks) 35 - 56. Functional. Many dogs become more serious about protective-aggressive behavior. A general persistence in behavior problems is noted and corrections become more difficult.
Age (weeks)104 - 208.Achievement. Protective-aggressive behavior can become especially purposeful. Problem behavior appears to become self-rewarding, habitual. Corrections markedly more difficult.