Psychomotor development refers to the origination of movement through conscious mental activity. There are three stages of psychomotor development: cognitive, associative, and autonomous. Children progress through average milestones of motor and cognitive development like head control, sitting, walking, and language skills between 6 months and 30 months. Factors like genetics, environment, and maternal psychological health can influence a child's development. Screening tests are used to check that development is appropriate.