What is the dependent and independent variable in this problem?

Evolutionary psychology suggests that symmetrical faces are perceived as more attractive than non-symmetrical faces, because these are visual indicators of good genetics and resistance to disease, injury, and developmental issues. Good genetics makes for offspring that will be more likely to survive (called the Good Genes model of mate selection).

In this test, participants viewed a series of faces on a computer screen. Some of these faces were digitally altered to be symmetrical, and others remained as normal non-symmetrical faces; each participant saw both kinds. For each face, the participant had to rate the attractiveness of the face on a scale from 0 (low attractiveness) to 100 (high attractiveness). Each participant's score is actually the average of the 5 symmetrical faces together, and the average of the 5 asymmetrical faces together.