What factors do you think influenced the development of these relationships?
Involvement of neural reward systems.
Reciprocity is the give and take in relationships.
You can click and drag on a bar to move the bar up, if you think that condition was more painful for the subject than the baseline control.
Try It Sexywallpaper initial screen below shows all blonde naked girls of the treatment conditions as a tiny bit more painful than the baseline control.
So does physical attractiveness matter at all?