No way to control for grooming, though. In a world with $400 face cream, grooming needs to be controlled for. I'd be curious how they did this.The photos were sourced from dating websites from major U.S. cities, and the researchers removed all identifying signs from the faces -- cropping them, standardizing them in height, and putting them into grayscale. All of the faces were also free of tattoos, piercings, or other markers.
Curious as to how the undergraduates were able to complete the task so successfully, Rule and Bjornsdottir next isolated specific facial features that might be cuing income status and conducted another test. Mouths were found to be the best wealth cues, although eyes were a strong indicator of income as well. What the authors eventually discovered, however, was that more significant than any specific part of the face was the apparent happiness of the face as a whole.
Damn, I started reading the actual study and their methodology was pretty exhaustive. https://www.researchgate.net/publication/317252320_The_Visibility_of_Social_Class_From_Facial_Cues I think your answer is in Studies 5 and 6, although I can't be sure. This was somewhat interesting to me:I'd be curious how they did this.
Perceptions of targets’ Positivity (a composite of positive affect, empathy, warmth, and reversed dominance ratings) and Attractiveness (a composite of attractiveness, health, and intelligence ratings) served as utilized cues in perceivers’ social class categorizations. That is, the participants in Study 1 were more likely to categorize as rich those targets that participants in Study 3 rated higher on Positivity and Attractiveness. This suggests that perceivers use class-related stereotypes (e.g., of the rich being happier and more attractive) when categorizing people as rich or poor. Only Attractiveness validly cued targets’ actual social class, however. Unsurprisingly, then, not all wealth-related stereotypes are correct.