Abstract
Psychological attributions based on facial appearance are frequently associated with shapes and proportions which is currently studied using photographs. The method of photo acquisition might affect subject's shapes and proportions, e.g., focal length, as shorter focal lengths produce barrel distortion.
Here we tested whether different focal lengths (50, 85, 105mm) affect facial perception. Our results showed that female facial photos taken with 50mm focal length were rated as significantly less feminine and attractive, similarly, male photos were rated as less masculine and dominant.
Subsequent GMM revealed focal length significantly affects facial shape of photographed subjects. Thus methodology of photo acquisition can influence results of studies using photos (type II error), probably due to different levels of distortion that influence shapes and proportions of morphological traits.
We recommend using the constant focal length, at least within individual studies, and we stress the need to employ a precise methodology in future studies.