"Mating-primed women demonstrated LVF bias when presented with targets lacking limbal rings, suggesting an avoidance response"

This could serve as an explanation why some men don't have the expected luck when hitting on women. For short term affairs at least. It is not the general physical appearance, no, it is a far minor yet apparently important small detail.  Like the lack of an outer ring around the iris.

Women’s short-term mating goals elicit avoidance of faces whose eyes lack limbal rings.

Abstract

Limbal rings are dark rings around the eye’s iris and their presence represents a good genes cue, which augments facial attractiveness. This communicative function implicates limbal rings as especially desirable in short-term mating contexts, suggesting a stronger motivation to approach prospective mates with limbal rings relative to those without. To assess approach and avoidance tendencies more directly, the current study adopted a line bisection task capable of assessing cortical activity. Whereas a right visual-field bias is associated with approach motivation, a left visual-field (LVF) bias is associated with avoidance motivation.

In this study, we activated women’s short-term mating motives (vs. a general positive affect control state) and presented a series of male and female faces with and without limbal rings over centrally bisected lines. Participants indicated which side of each line was longer to determine potential activation of consonant cortical areas.

Mating-primed women demonstrated LVF bias when presented with targets lacking limbal rings, suggesting an avoidance response, relative to targets with limbal rings. No differences in behavioral tendencies between targets with and without limbal rings emerged for control-primed women. Results indicate the importance of limbal rings in short-term mating decisions by demonstrating a behavioral aversion to prospective mates lacking this health cue. (PsycINFO Database Record (c) 2018 APA, all rights reserved)