In the psychology of Freud, the anal stage is said to follow the oral stage of infant/early-childhood development. This is a time when an infant's attention moves from oral stimulation to anal stimulation (usually the bowels but occasionally the bladder), usually synchronous with learning to control their excretory functions, a time of toilet training. Freud theorized that children who experience conflicts during this period of time may develop "anal" personality traits, namely those associated with a child's efforts at excretory control: orderliness, stubbornness, a compulsion for control, as well as a generalized interest in collecting, possessing, and retaining objects. Those whose anal characteristics continue into later life are said to be "anal retentive", or conversely, those who reject anal characteristics are said to have "anal expulsive" personality types. Some believe this to be a mild expression of obsessive-compulsive disorder or obsessive-compulsive personality disorder.
Although Freud's theories on early childhood have been influential on the psychological community, research suggests that the overall pattern of parental attitudes has a much more concrete effect on how an infant will grow up. There is no conclusive research linking anal stage conflicts with anal personality types.