|SUMMARY: Non-Mormons cannot distinguish Mormons from non-Mormons much better than through random guessing.|
On the other hand, there could be some truth to it (truth related to perception, not religious truth; ALF doesn't exist either). Mormons have been reported to be healthier than other demographic groups, which may manifest itself in terms of facial appearance (thereby religious perception), and many people are particularly well-attuned to facial features.
Nicholas Rule (University of Toronto, Canada) and coworkers carried out a study to test the hypothesis that facial features enable non-Mormons to distinguish Mormons from non-Mormons. Respectfully, I contend that they hype the minimal positive evidence they did find, although it still remains to be seen whether Mormons can identify other Mormons.
The scientists carried out five sets of studies, all using the following general stimuli (procedural modifications are noted where applicable). None of the participants were Mormon.
Facial images of explicitly Mormon and explicitly non-Mormon men and women, 18-30 years old, without facial adornments (e.g. glasses), were obtained on the Internet. Selection bias was avoided by using researchers who were blind to the purpose of the study to gather the images.
From this set of images, 160 Caucasians were randomly selected (80 Mormon men and women, 80 non-Mormon men and women). All of the images were cropped to exclude necks, clothes, and image backgrounds, and converted to grayscale.
Research assistants, again blind to the experiment, rated both groups (Mormon and non-Mormon) as equally expressive on a 7-point scale (neutral to very happy). None of the faces fell outside the neutral-to-happy range, e.g. none of the faces were angry or sad.
In the first study, 23 undergraduate students (4 males) categorized each face as Mormon or non-Mormon, and rated their perceived overall accuracy. In the second study, specific facial features were selected (e.g. eyes, nose, etc), and the same experiment was carried out with 146 undergraduate students (54 males).
In the third study, 54 undergraduate students (17 males) rated the faces on a 7-point scale of spirituality and health. In the fourth study, eighty individuals (36 males) rated the faces on a 7-point scale of skin texture, facial symmetry, and attractiveness.
In the fifth study, 55 undergraduate students (gender breakdown not reported) rated the health of generic Mormons and Protestants on a 7-point scale of health. What were the scientists' findings?
Minimal evidence, yet grand claims, for identification.
With the full photos, participants were only able to distinguish Mormons from non-Mormons by a few percentage points greater than chance, dropping even lower when partial facial features were evaluated. Even though the results were statistically significant, this doesn't demonstrate much predictive power.
The participants rated themselves as 28±17% accurate. While they greatly underestimated their accuracy, remember that the accuracy wasn't much better than chance.
Mormon faces were rated (on a statistically significant level) as being more spiritual and healthier than non-Mormon faces. No significant differences were found for either skin texture, facial symmetry, or attractiveness.
What all of this says to me is that although Mormons may be perceived to be facially different from others, these perceptions don't pan out very well in a standard test.
The scientists conclude their study by claiming to have found evidence that Mormons can be accurately perceived as such. On the contrary, they found that although Mormons are thought to be different, non-Mormons can't distinguish Mormons from non-Mormons much better than chance.
None of this answers the question as to whether Mormons can distinguish other Mormons from non-Mormons. Based on this study, I'll remain highly skeptical unless someone convincingly proves otherwise.
NOTE: The scientists' research was funded by the National Science Foundation and the Canada Research Chairs program.
Rule, N. O., Garrett, J. V., & Ambady, N. (2010). On the Perception of Religious Group Membership from Faces PLoS ONE, 5 (12) : 10.1371/ journal.pone.0014241