Very little human behavior can be classified as purely instinctive. This is because we are capable of responding on much higher level, involving learning. The question then is the extent to which primitive instincts provide basic drives which motivate behavior on higher levels. Some psychologists maintain that instincts are not present in human beings. Others acknowledge that they are present but that responses on higher levels over shadow them.
However, it is difficult to deny that some basic urge in all of us seeks self-preservation. Instincts are most evident in the infant, who has not yet developed behavior patterns on higher levels. For example all babies are born with a sucking instinct, except in some cases of premature birth. This is not a learned response, and is universal among babies.. Similarly, sudden noises cause crying and movement of the arms and legs. Very early in life however, higher level responses, based on learning in some degree, overshadow more primitive instincts. Just where instinctive behavior ends and learning, in some degree, begins is difficult to determine.