Objective: Although exergames are popular, few people take advantage of the potential of group dynamics to motivate play (and achieve associated health benefits). One motivation gain phenomenon has shown promise for motivating greater effort in partnered exergames: The Köhler effect (working at a task with a more capable partner where one's performance is indispensable to the group). This article examines whether a Köhler effect can be demonstrated in an exergame by exercising with a moderately

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... superior humanoid, software-generated partner. Materials and Methods: Male and female (n = 120; mean age, 19.41 years) college students completed a series of plank exercises using "CyBuddy Exercise," a program developed specifically for this study. In a lab in an academic building, participants completed the exercises individually and, after a rest, were randomly assigned to complete the same exercises again, but with a "live" human partner (HP) presented virtually, a nearlyhuman-like, humanoid partner (NHP), a hardly human-like, software-generated partner (HHP), or a no-partner control condition (IC), with equal numbers in each group (i.e., n = 30). Exercise persistence, perceived exertion, self-efficacy beliefs, enjoyment, and intentions to exercise were recorded and analyzed. Results: A 4 · 2 analysis of variance on the (Block 2 -Block 1) difference scores showed that a significant Köhler motivation gain was observed in all partner conditions (compared with IC), but persistence was significantly greater with HPs than with either NHP or HHP humanoid partners (P < 0.05). By the conclusion of the study, there were no significant differences among the partnered conditions in perceived exertion, self-efficacy, enjoyment, or future intentions to exercise. Conclusions: These results suggest that a software-generated partner can elicit the K} ohler motivation gain in exergames, but not as strongly as a partner who is thought to be human.