Imprinting = bird species from birth, Goslings attach to the first moving object. Imprinting occurs within the first few hours post birth. Approximately 4-5 hours was there critical period which was permanent. Goslings that imprinted onto humans also had an effect on later mate preferences. Concluded that Goslings are programmed to imprint (innate), humans also have a critical period which is 2/2 1/2 half years.