It is predicted that faces which are familiar will be perceived as being more friendly than faces which are unfamiliar. A set of 100 photographs of faces is obtained. Ten participants rate this complete set for "friendliness" using a seven-point scale. Before this, 50 of the photographs are used in a 'warm-up task' where the participant has to sort them according to sex. The mean rating for the sorted and unsorted photos is computed for each participant.