According to SMU psychologist Katherine Valentine, there is considerable debate among psychologists about whether physical dominance is advantageous in mating – that is, actually attractive to women. As such, they have been exploring facial width-to-height ratio (fWHR) as a possible physical indicator of male dominance. The scholars used results from over 150 men and women, ages 18 to 32, who participated in speed-dating events. The participants were all single and each speed-dating interaction lasted three minutes. Male speed-daters with higher fWHR, as measured by computer software, were independently rated as more dominant. Women not only expressed more interest in short-term relationships with these men, but were also more likely to choose them for a second date. These associations held even after the researchers accounted for the men's age and independently rated attractiveness.