Toilet training

Overview
Toilet training (or potty training) is the process of weaning a young child off diapers (or "nappies" in the British Isles and many Commonwealth countries) and training the child to use the toilet for urination and defecation. Toilet training is usually started and completed between the ages of eighteen-months and four years, though recent studies in Japan show that an increasing number of children are wetting their beds or wearing diapers full time, even in elementary school.

Psychology
Many psychologists believe that toilet training is among the most formative events of the human psyche because it is the child's first introduction to the fact that social imperatives can take precedence over bodily desires. According to Sigmund Freud, a child can have problems later in life if the toilet training does not go well, or is too strict. For example, as an adult a person could strive for perfection or excessive cleanliness because they were too harshly trained. The current popular wisdom on this subject is that toilet training is a mutual task, requiring cooperation, agreement and understanding between both the child and the caregiver. It is strongly recommended that coercion and shame are not used as disciplinary instruction tools during this phase of development.

Indeed, the best potty training techniques emphasize consistency and positive reinforcement over punishment.

History
Formal toilet training is a relatively recent phenomenon. It is necessary because contemporary society requires privacy for the act of excretion. Before the widespread social adoption of the private bathroom, most children learned toilet skills simply by observing. Such is still the case in countries where few members of society have private bathrooms.