Frequently asked questions

Informal, plain-language answers to the most common questions about this study's method and results.

Why weren't the photos shown side by side?

Because when the human brain judges an object, it first stores an image as a comparison reference. Showing photos side by side lets that reference drift toward an average of the faces on screen, undermining the reliability of the answer — how can you choose consistently if your own point of comparison keeps shifting? Instead, each photo replaces the previous one on screen, preserving a more intuitive comparison and reducing 'mean-induction' bias.

Why exactly eleven images?

Our ability to choose consistently is limited to a fairly small number of alternatives. Beyond a certain point, many people choose without a real criterion and, asked again, couldn't even reproduce their own earlier choice. Eleven alternatives proved to preserve response consistency.

Why does the questionnaire ask for so little information?

Studies of on-line survey participation show that for every question beyond seven, roughly one in three respondents abandons the form before finishing. The questionnaire was deliberately kept short.

Why isn't the sponsoring institution named in the questionnaire?

To avoid biasing the results: people with an affinity for the institution might try to 'help' the responses along, and people with the opposite reaction might try to invalidate them. Keeping the invitation neutral protects the quality of the sample.

Did the model consent to the use of her photos?

Yes, through a signed informed-consent form (reproduced in the dissertation). The original photographs were used only as a base for digitizing the facial features; the eleven final images are digital combinations of different facial components — none corresponds exactly to the person photographed.

Is this spam?

Spam is unsolicited commercial e-mail. This is a nonprofit, public-interest scientific research invitation. In the original collection, only 4 of 4,860 invited participants asked not to be contacted again — a high acceptance rate, suggesting the invitation was well received.

Couldn't the same person vote repeatedly to skew the results?

Technical safeguards against duplicate votes are in place (originally: IP address, network MAC address, and control cookies; in this reactivation, an anonymous per-browser identifier). Even if someone bypassed those safeguards, in samples of this size, isolated attempts wash out statistically — the result rests on the majority trend, not on outliers.

I didn't participate — how can my preference be 'represented'?

In large samples, Logistic Regression estimates trends for entire demographic profiles (region, age group, sex, occupation, etc.), not only for actual respondents. If your preference follows your group's pattern, it is already statistically represented. This doesn't invalidate preferences outside the norm — it simply describes the predominant behavior of the groups studied, with equal scientific legitimacy.

Is it valid to base esthetic conclusions on 'majority preference'?

Esthetic preference isn't fixed — it shifts with prior experience, occupation, sex, age, and even cultural mood. Still, measuring the central tendency of large groups is a legitimate and widely used scientific tool, provided variability (not just the mean) is also reported — as this study does when comparing groups against each other.

Is there a curious biological analogy for this kind of preference?

Yes — an interesting parallel comes from animal behavior research. In several species (reptiles, birds), female preference for certain male traits (such as tail length) shifts with environmental conditions: in times of plenty, more exuberant traits; in scarcity, more economical ones. A similar logic has been proposed for human facial esthetics: a baseline preference for the average (a 'normal,' symmetric, balanced face) combined with an extra premium for one trait that's slightly outside the norm — which may help explain why 'almost-average faces with one distinctive feature' are often judged especially attractive.

Does this topic extend beyond Dentistry?

Yes — the study draws on the Psychology of Perception, Evolutionary Biology, Statistics, and On-line Research Methodology, among other fields. The dissertation's Literature Review covers this territory with more than 150 references, from Da Vinci and Dürer to contemporary studies on the psychology of attractiveness.