Virtually all the males of our comparative groups had, at some time in their postpubertal lives, reached orgasm through self-masturbation: the percentages range from 92 to 100 per cent. Obviously such a universal phenomenon does not lend itself to comparative study on an “ever vs. never” basis.
The accumulative incidence, the percentage with masturbation experience by a given age, is likewise not a good comparative criterion because the range is so small. For example, 80 per cent or more of all groups had masturbated by age twelve. About all that can be said is that the aggressors and homosexual offenders vs. minors and adults tend to have, by any given age, more of their members experienced in masturbation than do other groups. This is particularly true of the homosexual offenders vs. adults who reach die ultimate 100 per cent mark by age twenty-one.
The age at which the first masturbation with ejaculation occurred (i.e., the age at first postpubertal masturbation to orgasm) closely parallels the age at puberty. In brief, males who reached puberty early had similarly early masturbation. For example, the median homosexual offender vs. adults reached puberty at 13.1 years of age, and ejaculated by masturbation at 13.3 years of age. This close correspondence is inevitable since the ability to ejaculate is a major criterion in establishing the age of puberty, and masturbation is the prime source of first ejaculation. However, the correspondence is less with increasing age at puberty: the median incest offender vs. adults, for example, reached puberty at 14.5 years and ejaculated in masturbation four months later at age 14.8. The differences in median age at first postpubertal masturbation are ordinarily small: a one-year span, from age 13.3 to 14.3, includes all gr6ups save two, the incest offenders vs. adults and the heterosexual offenders vs. minors whose medians are 14.8 and 14.5 respectively.
Age-specific incidence, the number with masturbation experience within a given five-year age-period, was calculated excluding all time spent in prisons or other closed institutions. Consequently, the presence or absence of masturbation as evidenced by our incidence figures is not influenced by involuntary isolation from society.
The general tendency among the single males is toward progressively lower age-specific incidence after the teens. From puberty to fifteen, when sociosexual activity is not well established, the incidences are high, all being above 70 per cent. In the next age-period, 16—20, the incidences remain high or even increase, owing to the addition of individuals who did not reach puberty until sixteen or later. From twenty on, however, the incidences decrease as sociosexual activity displaces masturbation and as the imperativeness of the sexual drive lessens. This is most dramatically seen in single; males of the prison group whose age-specific incidence falls from 88 per cent in age-period 16-20 to 67 per cent in age-period 21-25, then to 62 per cent, and finally to 46 per cent in age-period 31-35.
On the other hand, a few groups—chiefly the homosexual offenders and the peepers—resist this trend and maintain high incidence figures. Consequently, with some groups maintaining high incidences and other groups having decreasing incidences, the range among all groups widens: in age-period 16-20 it was from 76 to 98 per cent while in the following period it was 47 to 94, and still later 44 to 97 per cent. The resistance of the homosexual offenders to a reduction in incidence simply illustrates the important role that masturbation plays in the lives of the majority of homosexual males, a topic which is discussed in more detail in the section on homosexual offenders vs. adults. In the case of the peepers, it would seem reasonable to assume that masturbation was a concomitant of voyeurism.
Age-specific incidence among married males shows a similar decline, coupled with an expansion of range. For example, in the earliest age-period, 16-20, the range is 23 to 60 per cent; in age-period 31—35 it is 8 to 60 per cent.
Again some groups resist the decline, among them the exhibitionists, the incest offenders vs. children, and the homosexual offenders vs. adults. All three, one will recall, had either high or moderately high incidences of masturbation in premarital life up to age twenty.
The significance of these age-specific data is diminished by the gross-ness of our measurement: one act in a five-year period suffices to place a person in the positive incidence percentage. One-year rather than five-year calculations arc merited, and we hope sometime to do this.
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