One challenge in computer-supported groups is the maintenance of high performance motivation of group members because face-to-face interaction and social control are restricted. Based on research on the Kohler effect (Hertel, Kerr, & Messe, 2000), we expected high motivation of group members when their individual effort is highly instrumental for the group's success. First, a task paradigm was developed and validated to measure motivation in a computer task. Then, this paradigm was used to explore group members’ motivation in computer-supported dyads without face-to-face contact. Consistent with our expectations, motivation (and performance) of the group members was high and even exceeded the baseline of individual work (thus revealing motivation gains) when the individual's contribution was highly instrumental for the dyad's success (i.e., weaker coworker under conjunctive task demand). When instrumentality was low (i.e., weaker coworker under additive task demand), inconclusive results were obtained. Overall, the results demonstrate that motivation gains can be produced in computer-supported dyads, even without face-to-face interaction.