123 American male p's were tested, each p was in a group with several confederates. They saw 2 white cards on each trial- one had three comparison lines labelled A, B and C; the second had a line labelled 'X' which needed to be matched. On each trial, p's had to state which of the comparison lines matched the standard line 'X'. They were seated in tables of 7, with the participant always answering 6th. Study lacks population validity.