[1] Spanning the life period from birth to the age of 18 months, the oral stage is the first of the five Freudian psychosexual development stages: (i) the oral, (ii) the anal, (iii) the phallic, (iv) the latent, and (v) the genital.
Freud proposed that if the nursing child's appetite were thwarted during any libidinal development stage, the anxiety would persist into adulthood as a neurosis (functional mental disorder).
[3] The infant who is neglected (insufficiently fed) or who is over-protected (over-fed) in the course of being nursed, might become an orally-fixated person.
This fixation might have two effects: (i) the neglected child might become a psychologically dependent adult continually seeking the oral stimulation denied in infancy, thereby becoming a manipulative person in fulfilling their needs, rather than maturing to independence; (ii) the over-protected child might resist maturation and return to dependence upon others in fulfilling their needs.
Theoretically, oral-stage fixations are manifested as garrulousness (talkativeness), smoking, continual oral stimulus (eating, chewing objects), and alcoholism.