That is just grazing the surface of what is wrong with an experiment like this. For example:

- people may react differently to photos than they do to real people

- people may react differently in a lab than they do in a real life courting situation

- people may lie about their attractions for unfathomable reasons

- people may not even know what they are attracted to

- the people in the photos can't necessarily fake emotions convincingly

These kinds of issues confound most psychological experiments but you really can't dismiss them when it comes to sex.