Our daily life provides us a lot of opportunities to participate at work, learn and play with our peers: group learning in schools, training courses in the company, and even outdoor activities. The interactive roles of leaders and followers sometimes emerge and reorganize in our group activities. This study revealed both verbal and non-verbal cues for expressing emergent interactive roles in group activities. Objective evaluation through neutral third parties was conducted to select roles including leader, active or passive follower that the participants played in a triad assembly task. From the result of the correlation between behavioral data and third party evaluation, the interactive roles could have been characterized the amount of speech, i.e., potential leader talked more than potential followers. It was also suggested that the amount of gaze to other participants and the distance from them were useful cues for distinguishing active follower from passive one.