Erection Research

Lit Review
Related Article

Return Home


Even though limited to a small, self-selected sample, the present research using questionnaires linked with photo documentation yielded erection data that appear intuitively correct and support many of the basic findings of  the large self-reported data base of the Kinsey Institute.  The Kinsey data on erections were found to be an authoritative source of information for counseling—with several emendations suggested by the new, more directly verified data.  Specifically, the photo research implied these tentative changes to the findings of the Kinsey census sample:  (1) more n-curve erections, about 15%—rather than 5%—of the total, (2) more erection angles in the lower ranges, with at least one fourth—rather than 7%—below horizontal, and (3) a greater proportion of shorter erections, with about 40%—rather than 30%—of lengths in the 4.5 to 5.75 in. range.  Other findings of the Kinsey census sample were reinforced and affirmed by the photo sample.

We believe these suggested changes are in the correct direction, but because volunteer subjects were used, we cannot be sure how the magnitude or source of the observed differences are related to the general population of men in the USA.  As stated at the outset, the source of our findings could be derived from sexual orientation, nudism, secular trend, improved and verified measurement in the photo subjects, or self-reporting bias in the Kinsey subjects.

It seems plausible that one of the main sources of the present findings might be deep respondent biases away from the self-reporting of erections that are under 6 inches, below horizontal, or n-curved.  Photo verification procedures appear to mitigate the effects of these reporting tendencies (since on these factors, and these only, the relative frequencies were greater in the photo sample than in the Kinsey census sample).  Verification procedures cannot, however, solve the problems associated with subject self-selection.  It is quite possible that subjects who do not volunteer are motivated in their non-participation by the same biases that are expressed in self-reported data.  The photo sample could have produced its greater proportions of n-curve, shorter, and lower erections through accuracy of measurement, and nevertheless still may have been underrepresented in these areas—because these very characteristics may be a source of bias against volunteering.

If there is to be a completely satisfactory descriptive study of erections, an adequate method of recruiting a representative sample must be devised.  Still, by successfully obtaining photo-verified data on 81 volunteer subjects, a first step has been taken.  These new data have provided a basis for both substantiating and tentatively adjusting findings of the Kinsey self-reported data.  Primarily, the questionnaire/photo data call for increased percentages in some of the least-represented ranges of the erection spectrum.  On the other hand, some of the most highly-represented points in the Kinsey census sample distributions (e.g., 6 in. length = 21.9%, and 85-95º horizontal angle = 24.1%) are hardly credible, if, as logic would suggest, length and angle are continuous variables.  These numbers were likely artifacts of self-report in which the presumptive "average" or the most easily recognized position were chosen inordinately—a self-fulfilling prophesy.  If these dubiously high figures were corrected, they would provide one source of "room" in the length and angle distributions for the adjustments suggested by the photo research.

Haeberle, in a popular reference, asserts:  "The average length of a grown man's penis is...between 5 and 7 inches when erect."8  This gives a commendably broad definition of the average.  While the statement is undoubtedly true, and is duly followed by several comments emphasizing variability from one individual to the next, it still poses a problem for men who fall outside this "average" range, especially those whose erections are shorter than 5 inches.  For them and many others, a continuum is more helpful and informative than an average—because it enables every man to identify a place that is his own.  No erection is isolated.  Each individual can understand that his place on the continuum also implies other erections that vary from his, in both directions, by no more than millimeters in shape, angle, or size.  This is the same comforting understanding we have regarding our height, weight, hair color, and many other continuously variable human traits.

The documentation of an emphatically wide and smoothly continuous range in angle and length is perhaps the most useful and important contribution of the questionnaire/photo research.  The broadly inclusive description presented here can be a resource to therapists who find themselves needing to introduce factual and cognitive elements into therapy dealing with the anxiety-laden self perceptions of some clients.

Therapists Wanderer and Radell quote Masters, pioneering researcher on sexual dysfunction, as saying, "When we published Human Sexual Response, we purposely did not include information about the average size of penises.  To some degree, we hoped that by not doing so, we would neutralize the concept that penis size is crucial to sexual response."6  The opposite view has been taken by Wanderer and Radell themselves who say they have found "...that when sexual norms remain unknown, anxiety generally results.  This is because the unknown is frightening; for it is worse not to know than to know the worst."9