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Male-to-female transmission was observed in 7 couples. All infections transmitted from male to female partners originated in the penis with or without additional involvement of the scrotum. In particular, the penis shaft was a predominant source of infection either alone or with other genital sites. The cervix and anus were the most frequent targets of transmission from the men. Transmission of oncogenic HPV 16 comprised 1 of the 5 genital-to-cervix events. Male genital to female hand transmission was observed in 3 couples (D, E, and G).
The Sims 3 Penis 31
Male self-inoculation was observed in 11 men, including 3 for whom no heterosexual transmission was observed during the entire period of follow-up. Sixteen events involved transmission between different genital sites, 2 involved anal-to-genital transmission, and 3 involved genital-to-hand transmission. Most genital-to-genital events involved transmission between penis subsites. In 3 instances, male self-inoculation immediately preceded transmission of HPV to female partners (couples A and B).
Heterosexual transmission of the same HPV genotype to >1 anatomic site (excluding penis subsites) was observed on 13 occasions. Eight of these cases involved transmission from the cervix/urine to the penis and scrotum.
Heterosexual transmission of multiple genotypes to the same anatomic site during the same period was observed in 5 instances (couples A, B, D, F, and G); the scrotum was the target site on 3 of these occasions. In 1 case, different genotypes in the cervix and urine were each transmitted to both the penis glans and shaft (couple K).
The anus of women was both a major source and target of heterosexual transmission. We observed consistency between penis-to-female anus transmission and reported anal intercourse during the corresponding period. We previously demonstrated high genotypic concordance between concurrent cervical-anal infections in women, which indicates possible common sources of infection (20).
When Roberts returned to work, she encountered a torrent of abuse. Staff reportedly sketched a penis on the bathroom door, covered its door knob in engine grease and glued its light switch in the off position.
The context of the sexual relationship could influence penis size preferences. For example, the goal of the sexual interaction with a one-night partner tends to be pleasure . Women recognize that infection risks are higher from a one-night partner . While women adjust their behaviors for this risk, being less likely to engage in anal sex  and more likely to use condoms  with one-night partners, such risky behaviors themselves are often experienced as pleasurable . On the other hand, vaginal intercourse always causes tears in the vaginal mucosa  especially in the sensitive posterior fourchette , so women might prefer a smaller penis less likely to stress their physiology for regular, long-term mates. Thus, women might shift their preferences for penis size depending on the type and duration of sexual relationship.
Based on previous studies (see above) about the distributions of penis length and circumference, the average American erect penis length was estimated as 6 inches (15.2 cm) and circumference as 5 inches (12.7 cm). Models were created to range +/- 3.0 S.D. across each dimension (see Fig 1). This resulted in length ranging 4.0 inches to 8.5 inches (10.2 cm to 21.6 cm), and circumference (circumference) ranging from 2.5 inches to 7.0 inches (6.4 cm to 17.7 cm), using 0.5-inch (1.3 cm) increments (see Fig 1). This yielded a 10 X 10 matrix of 100 possible sizes. However, such a large choice set could overwhelm participants. We chose to sample 1/3 of this space, yielding 33 models across the range of space.
The penis model shape was a cylinder, representing the shaft, topped by a dome, representing the penis head (see Fig 2). Of course, the human penis shaft is comprised of three corpora that could be better represented by a rounded triangle and a more complex glans. Also, no veins, testicles, or other details of the penis were portrayed. These details were not represented for three reasons. First, there are no mathematical descriptions available to accurately represent normal proportions of more complex penile structure. Second, women generally rate male nudes as less attractive than heterosexual men rate female nudes , so making the penis model more realistic might have provoked negative responses. Third, the study was focused on overall penis size, not penis shape or surface details. While one motivation behind the current study was to improve the ecological validity of the stimuli, these concerns suggested starting with a more simplistic, erect penis model.
Next, the participant answered questionnaires (described below) presented on a computer in a private room, using a secure connection, on private laboratory server space scripted by the first author in php5. This took about 50 minutes and included the penis size preference tasks and questionnaires (see below). Computer presentation of questionnaires has been shown to increase the reporting of socially less desirable behaviors . After the questionnaires, she completed a 10-minute computer task (data to be reported elsewhere) assessing attention to sexual images. Afterwards, the participants was debriefed, offered the opportunity to ask questions, and given $20 cash. The study protocol, including Informed Consent protocol, was approved by the University of California, Institutional Review Board.
The self-report questionnaires included demographic information (e.g., age, ethnicity, sexual orientation), sexual history (e.g., number of sexual partners, sexual coercion, whether penis size played a role in relationship dissolution(s), etc.), and current sexual functioning (e.g. orgasm rates, ease of lubrication, relationship monogamy status, pain during intercourse). These were used to characterize the sample. Other personality questionnaires were included, such as the Sexual Desire Inventory  and the Sociosexual Orientation Scale  to characterize the sample.
Most (N = 48) women selected the exactly correct model (in both length and circumference) at immediate recall (see Fig 5). About half (N = 31) of women selected exactly the correct model at delayed recall. There was a main effect of dimension predicting model selection error (F(1,73) = 11.6, p
These data are generally consistent with Mautz et al. (2013), which asked women to rate the attractiveness of life-sized, projected, rotating drawings of male figures with flaccid penises of various sizes. Their participants preferred phalluses 2SD above their estimated population-average penis size, whereas our participants preferred penises that were only a little above average. This difference may be due to their images depicting flaccid penises, whereas our models depicted erect penises.
A larger penis could contribute to infection risks, such that a larger penis on more risky one-time partners elevates risk. A larger penis has been associated with higher infection rates amongst men who have sex with men . Also, an increase in friction during intercourse from a condom is associated with the introduction of more bacteria into the vagina [74, 75] and more vulvar erythema . Finally, women report that condoms increase their experience of pain during intercourse [76, 77]. Anything that increases friction during intercourse may promote genital injury, indirectly increasing infection risk. A larger phallus would increase friction relative to a smaller phallus. These potential complications of a larger penis suggest why the human penis has not evolved to be larger.
Generating haptic stimuli was relatively cost-effective and simple. Free software was available for generating print files. Also, the print files are shared online to allow exact future replications. Undergraduate research assistants were able to create and monitor the work flow. The 3D printer used is now widely, cheaply commercially available. Expanding this model into preferences pertaining to other domains, or even for other penis shape preferences, appears desirable.
As a first study using life-sized 3D models of erect penises to investigate preferences, some limitations exist. Models were not perfectly ecologically valid. They were blue to minimize racial skin-color cues. They were made with rigid, odorless plastic. They were a simplified dome-on-cylinder form rather than realistically shaped and textured. The male body was neither described nor portrayed. There were also limitations of self-report approaches. Men and women appear to have actually become less approving of one-time sexual partners since 2001 , which may affect the preferences that they are willing to report regarding such partners. Also, a significant minority (15 of 75) of women chose not to report a preference for penis size in short and long term partners, but did answer both of the recall questions. Perhaps these women did not have a clear preference, consistent with weak penis size preferences reported in some previous studies [54, 65]. This could be viewed as a strength, insofar as women did not feel compelled to answer in cases where they did not feel they had a strong enough basis to generate an answer.
Another limitation is sexual inexperience among some participants. Fifteen women in our sample indicated that they had never experienced sexual intercourse. This inexperience could underlie some of the size preferences observed. For example, women generally anticipate more pain with their first intercourse than they actually experience , so they may show risk-averse penis size preferences (for shorter length and thinner circumference than they may prefer with experience). Less experienced women may also be less accurate in their size estimates. However, a follow-up analysis showed that having had sexual intercourse (yes or no) did not predict penis size preferences, arguing against this possibility. A related limitation is that the experimental protocol necessarily limited the sample size, and these women were recruited largely near a college campus. There may be other biases in the sample related to the recruitment method and sample size that were not identified.