Each of these fundamental forces interacts together to shape human development. Within biological, psychological, and sociocultural forces there are normative forces classified by age, normative forces classified by history, and non-normative forces. Normative forces classified by age and history in each area are experienced by almost everyone at a similar time in the life course, as well as across generations. Aspects of non-normative forces in each area are experienced by very few people. Biological force is the first of the four forces. This force represents genetic and health-related factors that influence development. Puberty is an example of age-related normative forces, the 1918 influenza pandemic is an example of age-classified forces, and some diseases are an example of non-normative forces. Secondly there is psychological strength which represents the perceptual, cognitive, emotional and personality factors that influence development. Language acquisition is an example of normative age classification. Technological literacy during the 1970s or today among Millennials is an example of normative forces classified by history. An example of non-normative forces is psychological disorders. We next move into sociocultural forces that represent the social, cultural, ethical/racial, and interpersonal factors that influence development. Going to kindergarten is an example of age-related normative forces. Normative forces related to history provide the example of network generation and SMS. A professional working woman who has children in her forties is an example of nonnormative forces. The last of the four forces are the life cycle forces which represent the effects that certain events have on people. They affect people differently depending on the particular person experiencing the event and the particular time at which the event occurs