Freud, in his theory of sexuality, divided the human growth process in phases called psycho-sexual. Everybody would go through his growth-process following a pre-established order, whereupon would the impulses be concentrating on erogenous zones.

In his theory, since early childhood, someone has already masturbated. It’s clear that masturbation, as it’s commonly known, will only, spring into action in adolescence. At which point people come into a certain sexual maturity and become able to derive pleasure out of genital touching.

The human psycho-sexual development phases stand for, - the oral phase, which covers from birth to the age of 2, so distinguished by pleasure surrounding the mouth and the lips. The child, in suckling a rubber teat, feeding-bottle or the mother’s breast, would derive a profoundly delightful sensation of tenderness, warm, care, which for her is highly pleasurable. Hence, she pleases herself and her minders as well.

Thereafter, the anal phase gears up, which spawns from the age of two at around four as the child begins to gain control over her biological urges- sphincters. At which point, pleasure itself lies within the act of retaining and releasing her sphincters, and so the way peers perceive it. For the child, the sensation from creation of something that is hers is highly blissful, and its excretion yields a rather delightful sensation in her anus and urethra. If the grownups happen to foster her discoveries, she would feel gratified and would easily go through this phase with no further concerns. The child has no concept of genitality up until now, only knows that its sensation feels good.

The following phase is the phallic-one-from four to six, through which the child by the first time finds out the difference between boys and girls. She gets to know that boys have penises and girls have vaginas. In this phase the Oedipus complex takes place- which is the child’s love by the genitor of the opposite sex- herein not intended to explain it, though.

When the child discovers her sex organs, begins to touch herself, which in turn copiously generates pleasure.  In this phallic phase there is no turn on, only the nice sensation of touching herself. Most relatives and childcares repel this attitude of the child, punishing her most of the time. It’s the fear of punishment that determines the so-called Oedipus complex resolution.

Thereof, boys and girls enter into the phase by Freud called latency, which lasts from about two to twelve years old. In latency, there is not any erogenous zone. It’s the phase that the child detaches oneself from sexuality entirely, and there is none, technically, masturbation wise.

Along with puberty, someone rediscovers his erogenous zones, which goes back to sexual organs. The difference of the phallic phase to this one is that, along with the physical development, the hormonal increase, boys and girls feel real pleasure in touching themselves, by most people known as masturbation.

Thus adolescence is the epitome of masturbation. Both sexes get their first sex flings, by masturbating themselves. It’s the moment of unveiling your body and to get set for grownup sexuality, which according to Freud was regarded as having sex with the partner. Only lately in adolescence would orgasm being reached. Up until then, there was no climax in masturbation, just the pleasant sensation of touching. Therein sips the understanding that infantile masturbation is different from what takes place in adulthood. 

In the first, its function is to indulge an impulse with no sexual means, in the second, pleasure is essentially sexual.