Influences on Conformity in Group Settings

In an experimental study on social influence, researchers conducted a variant of Asch's conformity experiments, where participants were asked to judge the length of lines in a group setting. In this modified version, participants were accompanied by two confederates who initially provided the correct answers but then unanimously switched to incorrect responses during the critical trials. The study aimed to explore the effects of group unanimity on conformity rates. Which of the following factors is most likely to significantly influence the participant's decision to conform under these specific circumstances?