In this experiment you were asked to press keys to determine how long you viewed each face
for. There were 24 identities showing two expressions (12 male and 12 female). Pressing one
key ‘bought’ you more time with the face (100ms extra per keypress), pressing the other key
meant that you had less time with the face (100ms less per keypress). If no key was pressed
the face was presented for 3000ms. This is a behavioural economics style paradigm designed
to explore which factors people want to see more of.
You will have noticed that a lot of factors related to the faces varied during the experiment.
Only some of them are important for your lab report.
The important variables for your lab report are:
1. The attractiveness of the faces. Half of the identities have previously been rated to be
high in attractiveness, the rest were rated as less high/average in attractiveness (12
high attractive, 12 less attractive).
2. The emotional expression shown. Each identity was shown with both a happy
expression and a neutral expression.
In your analysis we want you to test:
1. The hypothesis that people show an attractiveness bias i.e. that they choose to view
highly attractive faces for longer than less attractive faces.
2. The hypothesis that people show a happiness bias i.e. that they choose to view happy
faces for longer than neutral faces.
After the main experiment you were also asked to rate the faces on scale of 1-7 for their
attractiveness. This is a check that our previously established grouping of faces to
attractiveness labels is correct in this sample.

Study of faces purpose in social interaction