Adolescent Males' Willingness to Report Masturbation.

Information about adolescent sexual behavior is derived almost entirely from self-report. In general, the reliability and validity of self-report data appear to be good, although more methodological work is needed (Sonenstein, Ku, & Pleck, 1997). The misreporting of sexual activity that does occur usually is not random, having been linked to demographic characteristics of respondents such as age or sex (Brener, Collins, Kann, Warren, & Williams, 1995; Newcomer & Udry, 1988; Siegel, Aten, & Roghmann, 1998). Problematic reporting may also vary by type of sexual behavior, depending on its salience or sensitivity (Catania et al., 1996; Petersen & Catania, 1997).

Masturbation is one of the most prevalent sexual behaviors and is a highly salient feature of sexuality for adolescent males (Gagnon & Simon, 1973; Laumann, Gagnon, Michael, & Michaels, 1994). However, because masturbation is also one of the most sensitive behaviors for survey assessment (Bradburn, Sudman, Blair, & Stocking, 1978; Cantania, Gibson, Chitwood, & Coates, 1990; Catania, McDermott, & Pollack, 1986; Clark & Tifft, 1966; Johnson & DeLamater, 1976), it is rarely studied. In a national sample of adults assessing the relative "question threat" of items tapping drinking, gambling, drug use, and sexual activity, more than half of respondents rated questions about masturbation as making most people very uneasy (Bradburn et al., 1978). This finding represented the greatest consensus regarding "threat" among all items examined. Earlier work had confirmed the sensitivity of questions about masturbation through a comparison of confidential survey self-reports and later answers from the same male respondents given in the context of polygraph analysis. Out of a list of 35 deviance and sexual behavior items, only six behaviors, none of them sexual, were reported less accurately than masturbation (Clark & Tifft, 1966). Masturbation was consistently underreported; in tact, respondents were more willing to report rape and homosexual experiences than masturbation activity.

Lower levels of sexual experience and knowledge have been associated with higher perceptions of threat from questions about sexuality (Catania et al., 1986). The sensitivity or threat issues surrounding masturbation reports may therefore be especially pertinent during early adolescence, when individuals have less partnered sexual experience. Rather than being perceived as a normal sexual outlet, masturbation may be seen as a tacit admission of not having "real" sex (Coles & Stokes, 1985). Masturbation is also associated with feelings of guilt and anxiety among teens (Coles & Stokes, 1985). Even among male college students, almost two thirds report feeling some guilt about masturbating (Gagnon, Simon, & Berger, 1970).

Evaluations of inconsistencies over time in adolescents' behavioral reports also suggest the sensitivity of the topic. In an analysis of the rescission of previously reported sexual behaviors in a 2-year longitudinal study of adolescents, Rodgers, Billy, and Udry (1982) found that White males were almost twice as likely to rescind reports about masturbation as about intercourse, while Black males were almost four times as likely. The authors concluded that these elevated percentages of inconsistent responses reflected the sensitivity of survey questions about masturbation.

Kinsey, Pomeroy, and Martin (1948) reported that about 88% of adult males indicated in retrospective reports that they had masturbated by age 16. Approximately 93% of males reported that they had masturbated by age 25, making masturbation experience almost universal among males by early adulthood. Relatively few studies have assessed adolescent masturbation behavior since Kinsey's work, and, of those available, study designs (e.g., face-to-face interviews versus confidential self-report) and sample sizes vary markedly. In studies published in the early 1970s, reports of ever having masturbated from high school- and college-aged males ranged from 70% to 89% (Elias & Elias, 1975; Gagnon et al., 1970; Sorensen, 1973). More recent cross-sectional and longitudinal work based on middle school- and high school-aged males has yielded lower prevalence figures, with about a third to less than half of males reporting ever having masturbated (Halpern, Udry, Campbell, & Suchindran, 1993; Udry, 1988). In some cases the percentages of males reporting masturbation behavior are lower than the percentages reporting coitus.

In contrast to the low levels of masturbation experience reflected in contemporaneous reports from 13- to 16-year-old adolescents, Leitenberg, Detzer, and Srebnik (1993), using retrospective data from a college student sample of 18- to 20-year-olds, found that 67% of males reported they had masturbated by age 15. This figure is substantially lower than that reported by Kinsey based on his retrospective data, but higher than recent reports from 15-year-old adolescents. The extent to which the differences across studies may be attributable to historical changes in behavior, sampling, or other design differences is unclear. However, given the discrepancies between reports of ever having masturbated and the ages reported for age at first masturbation experience in cross-sectional samples, some authors have suggested that a willingness to report masturbation may increase across the teen years (Coles & Stokes, 1985). In early adulthood, individuals may retrospectively reveal adolescent masturbation activity that they would have been unwilling to reports as teens.

We examined this issue directly by comparing contemporaneous and retrospective self-reports about adolescent sexual behavior. Although our primary interest centered on masturbation, we included two other sexual behaviors, wet dreams and coitus, in our analyses in order to tap involuntary and partnered behavior, respectively. Wet dream experience is sometimes used as an indicator of pubertal maturation for males when clinical examinations are not possible. Coital initiation is commonly measured in surveys of adolescents. In fact, initiation and frequency of coitus are often the only aspects of sexual behavior that are measured.

For comparison, we also examined contemporaneous and retrospective reports of nonsexual problem behaviors. These included smoking cigarettes, getting drunk, smoking marijuana, stealing property, and vandalizing property. Retrospective reports of deviance behaviors and age of onset are often used when researchers wish to know when offenders committed their first crime or initiated status offenses (Henry, Moffitt, Caspi, Langley, & Silva, 1994). Early onset of delinquency has been identified as a key variable in crime career trajectories (Farrington, Loeber, & van Kammen, 1990), and has important implications for theoretical models of delinquency such as Moffitt's (1993) life-course persistent versus adolescence-limited distinction. Previous assessments of agreement between contemporaneous and retrospective measures of delinquency have concluded that agreement is moderately good, especially for highly salient experiences such as court appearances (Henry et al., 1994). For stigmatized or sensitive behavior, the number of respondents who deny a behavior they have actually experienced is expected to be larger than the number who falsely report behavior they have not experienced. Based on earlier work examining question sensitivity and threat (Bradburn et al., 1978; Clark & Tifft, 1966) and the net negative bias expected in surveys for sensitive behavior (Turner, Miller, & Rogers, 1997), we expected that the behaviors examined here were likely to be subject to underreporting during adolescence.

METHOD

Participants

As part of a study of physiological reactivity to novelty, we attempted to locate and reinterview 99 White males who had participated for 2 years in a study examining biosocial determinants of adolescent social development and sexual behavior. Participants in the original adolescent project had been randomly selected from among five middle schools in a county in a southeastern state. Mean age at study entry for the sample was 13.2 years, and ranged from 12.7 years to 13.9 years. The sample was primarily middle and upper middle class (see Halpern et al., 1993, for full sample description). Measures of physical growth, pubertal development, hormone changes, behaviors, and attitudes were measured at semiannual intervals during the original study period, which extended from 1986 to 1989. One year later a final adolescent assessment was conducted.

Of the 99 adolescents from the original project, 15% of respondents could not be located or contacted for follow-up, and 25% refused adult participation either through active refusal (25% of the refusals) or failure to return questionnaires/show up for study appointments. Sixty percent (59) of adolescents from the original project completed follow-up questionnaires in early adulthood. Data from adult questionnaires, along with earlier questionnaires from the adolescent project, were used in the present analyses. At the time of adult follow-up, the mean age was 21.5 years (S.D. = .5).

Sample Selectivity

Using data collected in the original adolescent study, we conducted regression analyses comparing respondents who did and did not participate in the adult follow-up. A range of demographic and behavioral variables was examined. Follow-up participants did not differ (p [is greater than] .05) from non-participants on age, mother's education, pubertal development, average salivary testosterone values for the first 6 months of study participation, scores on the Peabody Picture Vocabulary Test (PPVT) (Dunn & Dunn, 1981), and scores on the Block Design subtest of the Wechsler Intelligence Scale for Children (WISC-R) (Wechsler, 1974). They were also no different on adolescent reports about a number of the behaviors analyzed here including masturbation, wet dreams, stealing property, or being picked up by police. However, as adolescents, participants in the adult follow-up made higher grades (p = .008) than nonparticipants, were less likely to have had sex (p = .001), were less likely to have used substances (smoke cigarettes, p = .02; get drunk, p = .003; smoke marijuana, p = .01), and were less likely to have vandalized property (p = .02).

Behavioral Measures

The sexual behaviors we examined were wet dreams, masturbation, and sexual intercourse. Nonsexual behaviors examined were smoking cigarettes, getting drank, smoking marijuana, stealing property, and vandalizing property. Reports about each of these behaviors were collected semi-annually during adolescence and once at the adult follow-up.

At each semiannual assessment in adolescence, respondents were asked if they had ever done the sexual behaviors (no/yes). For nonsexual problem behaviors, respondents were asked how often they had done the behavior in the previous 6 months (answer categories ranged from never to more than 10 times). Using interview and birth dates, we calculated respondents' ages at the time of the first reports of each behavior. In early adulthood, respondents were asked if they had ever done the behavior and, if so, they were asked to report how old they were the first time they performed the behavior. Item wording varied slightly between adolescence and adulthood, and is described in the appendix. At both the adolescent and adult assessments, behavioral measures were reported in confidential, self-administered questionnaires. Interviewers did not have access to respondents' answers.

RESULTS

To examine behavioral prevalence based on contemporaneous versus retrospective behavioral reports, we compared the proportions of respondents who reported adolescent experience of a behavior during adolescence (i.e., at some time during their adolescent study participation, regardless of rescission) with the proportions of respondents who reported adolescent experience of a behavior as an adult (i.e., reported an age at first experience that preceded or fell within their time of adolescent study participation). Figure 1 displays these percentages for each behavior. Based on McNemar's (1947) Chi Square test of proportions for paired data, only three behaviors yielded significant (p [is less than] .05) differences between the proportion of respondents reporting adolescent experience as an adolescent versus as an adult; these were masturbation ([X.sub.(1)] = 4.77, p = .029), vandalizing property ([X.sub.(1)] = 10.89, p = .001), and getting drunk ([X.sub.(1)] = 4.46, p = .035). Of all the behaviors examined, masturbation was unique in that it was the only behavior for which adult reports about adolescent experience exceeded adolescent reports. For all other behaviors, respondents were either more likely to report adolescent experience as an adolescent than as an adult (e.g., vandalize property, get drunk) or reports from the two age periods were similar or identical (e.g., coitus, smoking cigarettes).

[Figure 1 ILLUSTRATION OMITTED]

For the sexual behaviors, we were also able to compare reports in early adulthood with a behavioral report about "ever done" at a single assessment at the end of adolescent study participation. Comparison with an adolescent report at a single point in time is more comparable to data that are likely to be available for most studies of adolescent sexuality (compared to the repeated measurements over time that were used in the previous analysis). Figure 2 displays parallel percentages for the single assessment comparison. Again, of the three sexual behaviors only masturbation yielded a significant difference between proportions of adult and adolescent reports of adolescent experience. This is consistent with our earlier analysis, but the reporting differences for

masturbation are even more striking. Differences for wet dreams and coitus were small and not statistically significant, but as in the previous analysis showed slightly higher reporting during adolescence.

[Figure 2 ILLUSTRATION OMITTED]

We compared adolescent and adult reports about adolescent experiences through an alternative strategy of reviewing the proportions of respondents whose adolescent and adult reports are inconsistent. Figure 3 plots the percentages of respondents who reported adolescent experience as an adult but not as an adolescent, and the percentages who reported adolescent experience as an adolescent, but not as an adult. Figure 3 contains the same information presented in Figure 1, but this alternative presentation highlights the patterns of inconsistencies in reporting. As noted in the previous analyses, masturbation was unique; it was the only behavior for which more respondents were likely to report adolescent experience only as an adult. For all other behaviors, the inconsistency pattern was either reversed or there were no differences.

[Figure 3 ILLUSTRATION OMITTED]

Finally, we explored possible correlates of inconsistency in masturbation reports. Because of the small sample size, all reporting patterns could not be examined individually. We therefore compared respondents who did not report adolescent masturbation experience in adolescence but did report it in adulthood to all other respondents. We examined two possible adolescent correlates suggested by earlier literature, age and partnered sexual experience, as well as three other variables: relative pubertal status, socioeconomic status, and attitude about masturbation. The specific measures were age, cumulative light petting experience (e.g., kiss and hug for a long time, touch breasts over clothes), cumulative heavy petting experience (e.g., touch sex organs under clothes or with no clothes on), cumulative coital experience, a pubertal factor score indicating the respondent's relative development on secondary sex characteristics, mother's education, and the respondent's degree of agreement (5) or disagreement (1) with the statement "Masturbation is a harmless way to get sexual pleasure." Behavior, pubertal status, and attitude were measured semiannually. Each of the potential correlates, except masturbation attitude, is described in detail in Halpern et al. (1993).

Of these variables, only pubertal status ([X.sub.(1)] = 8.68, p = .003) and masturbation attitude ([X.sub.(1)] = 5.40, p = .02) were associated with the selected reporting pattern. Boys who were relatively more pubertally developed or who agreed that masturbation is harmless were significantly less likely to report adolescent masturbation experience in adulthood but not in adolescence.

DISCUSSION

Although we do not have objective criteria by which to determine the accuracy of adolescent and adult reports of sensitive behavior, our analyses clearly indicate that self-reports about masturbation are fundamentally different from reports about other types of sexual activity and from reports about illegal or problem behaviors. By age 16, a majority of the present sample had reported masturbation behavior at least once. However, only a third of respondents reported that they had ever masturbated at any given adolescent assessment, including the final assessment at age 16. Of the range of behavior examined here, masturbation is the only adolescent experience that is significantly more likely to be reported during adulthood than during the adolescent period itself. If we consider the higher adult report as accurate, we would underestimate masturbation experience by about 15% using adolescent reports, even multiple adolescent reports over a 3-year period. Reliance on a single adolescent report about masturbation, the circumstance that is most typical in studies of adolescent sexuality, may underestimate the percentages of experienced teens by as much as one third. These interpretations assume that adulthood is a condition that would reduce a negative reporting bias in sensitive behavior, and that higher rates of reporting may therefore be interpreted as more accurate. For the other sexual dimensions examined, coitus and wet dreams, retrospective adult reports and contemporaneous adolescent reports were not significantly different.

Masturbation appears to be a particularly sensitive dimension of sexual behavior, and even with the use of confidential reporting techniques it is likely to be significantly underreported during adolescence. Our findings also indicate that the willingness to report masturbation increases with age, a possibility that has been previously suggested but to our knowledge not directly tested. These conclusions are consistent with previous findings based on polygraph validation of self-reported sexual and deviant behavior (Clark & Tifft, 1966), and with direct ratings of the "threat" or discomfort that questions on a variety of sensitive topics are thought to elicit.

We expected that adolescents might be especially uncomfortable reporting masturbation behavior because, on average, they will be less sexually experienced than adults. It is the rare parent who openly discusses masturbation with their adolescent son and touts it as an appropriate and normal sexual outlet. For adolescent boys, partnered sexual experience may be seen as a marker of' achievement or adequacy, and of a transition to adult status, whereas masturbation may be viewed as a secret substitute for preferred partnered activity. However, our exploration of the correlates of apparent underreporting during adolescence did not yield significant relationships with partnered sexual experience. Of the variables examined, only relative pubertal status and attitude about masturbation were associated with underreporting. It is logical that boys who have a more positive attitude toward masturbation would be more likely to report it. However, given that partnered sexual experience was unrelated to reporting inconsistency, the reasons underlying masturbation underreporting among boys who are relatively less pubertally developed are unclear.

Of the six nonsexual problem behaviors examined, only two--vandalizing property and getting drunk--showed significant differences between adult and adolescent reports. However, these adolescent experiences were more likely to be reported during adolescence, and not in adulthood. If we consider the higher percentage to be more "accurate," relying on adult retrospective reports would mean underestimating the percentage of adolescents who got drunk or vandalized property by 12% and 24%, respectively. These findings, like those from earlier studies, suggest that retrospective reports of more salient delinquency experiences (e.g., being picked up by police), while slightly lower, may be reasonable approximations of contemporaneous reports. For some problem behaviors, like vandalizing property and drinking, retrospective reports may provide significant underestimates of experience. Interestingly, the start or exploration of cigarette smoking, like the onset of coital activity, appears to be well remembered.

The generalizability of the present findings may be limited by issues of sample selectivity and sensitization. The 59 males comprising the current sample did not differ from our original sample in age, pubertal development, testosterone levels, masturbation reports, or wet dream reports. However, respondents who participated in the adult follow-up made better grades in school during adolescence and were less likely to have had sex by the time of entry to the adolescent study. These latter factors may be associated with higher data quality. Earlier work has demonstrated that race and gender may be associated with honesty and consistency in reporting sexual behavior (Rodgers et al., 1982; Siegel et al., 1998). Unfortunately, we were not able to explore those factors in the present analyses since our sample was limited to White males.

The results of our analyses suggest that even in the context of confidential reporting techniques and a longitudinal research design in which the confidentiality of reports of sexual activity, and even illegal activities, has been repeatedly demonstrated to respondents, masturbation experience is underreported during adolescence. These findings have implications beyond estimates of behavioral prevalence. For example, use Of wet dream reports as a marker for pubertal maturity may be a reasonable strategy, at least in terms of the issue of reporting candor. However, use of adolescent reports about masturbation as an indicator of sexual interest, which we have done in our own research, may be problematic and perhaps even misleading. Given the distinctive assessment issues related to masturbation, it is unclear whether contemporaneous adolescent reports are superior to those collected retrospectively in adulthood.

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Manuscript accepted March 30, 2000

APPENDIX

Adult wording:

Have you ever had a wet dream (ejaculated while you were dreaming)? (no/yes)

How old were you the first time this happened?

Have you ever masturbated? (no/yes)

How old were you the first time this happened?

Have you ever had sex (sexual intercourse) with a woman? (no/yes)

How old were you the first time you had sex with a woman?

Have you ever: smoked cigarettes, gotten drunk, smoked marijuana, stolen something worth $50 or less, damaged or destroyed property, been picked up or arrested by the police. (Presented as separate items, no/yes)

(If yes)--Age (in years) when first done

Adolescent wording:

Have you ever had a wet dream (had thick white liquid come out of your penis during a dream)? (no/yes)

Boys sometimes masturbate, or play with their penis until it gets hard, to have a good feeling. Have you ever done this?

(no/yes)

To have sex (sexual intercourse) is when a male places his penis into a female's vagina. This is sometimes called "making love," "screwing," "getting laid," or "going all the way." How often have you had sex with a girl, if ever (never, 1 time, 2-3 times, 4-10 times, more than 10 times--coded 0/1 for these analyses)

How many times did you do each of these things in the past 6 months:

Get drunk
Smoke cigarettes
Get picked up by the police
Smoke marijuana
Steal something worth $50 or less
Damage or destroy property

Answer categories are never, 1 time, 2-3 times, 4-10 times, more than 10 times; coded 0/1 for no/yes for this analysis.

Portions of this manuscript were presented at the Seventh Biennial Meeting of the Society for Research on Adolescence, San Diego, CA, February 26 - March 1, 1998.

This research was supported by a research grant (HD12806) to J. Richard Udry from the National Institute of Child Health and Human Development (NICHD), a center grant from NICHD to the Carolina Population Center (HD05798), and a Clinical Research Unit Grant (RR00046) from the National Institutes of Health.

Address correspondence to Carolyn Tucker Halpern, Carolina Population Center, CB #8120, Chapel Hill, NC 27516-3997; email: [e-mail].