Freud's psychoanalytic theories
The second stage is the anal stage, which lasts from eighteen months to three years of age. During this stage, the infant’s pleasure seeking centers are located in the bowels and bladder. Parents stress toilet training and bowel control during this time period.  Fixation in the anal stage can lead to anal-retention or anal-expulsion. Anal retentive characteristics include being overly neat, precise, and orderly, while being anal expulsive involves being disorganized, messy, and destructive.