title: Is My Exercise Partner Similar Enough? Partner Characteristics as a Moderator of the Köhler Effect in Exergames.
abstract: OBJECTIVE
  Recent research has shown the Köhler motivation gain effect (working at a task with a more capable partner where one's performance is indispensable to the group) leads to greater effort in partnered exercise videogame play. The purpose of this article was to examine potential moderators of the Köhler effect by exploring dissimilarities in one's partner's appearance, namely, having an older partner (compared with a same-age partner) and having a heavier-weight partner (compared with a same-weight partner).
  
  
  METHODS
  One hundred fifty-three male and female college students completed a series of plank exercises using the "EyeToy: Kinetic™" for the PlayStation(®) 2 (Sony, Tokyo, Japan). Participants first completed the exercises individually and, after a rest, completed the same exercises with a virtually present partner. Exercise persistence, subjective effort, self-efficacy beliefs, enjoyment, and intentions to exercise were recorded and analyzed.
  
  
  RESULTS
  A significant Köhler motivation gain was observed in all partner conditions (compared with individual controls) such that participants with a partner held the plank exercises longer (P<0.001) and reported higher subjective effort (P<0.01). These results were unmoderated by partner's age and weight, with one exception: Males tended to persist longer when paired with an obese partner (P=0.08).
  
  
  CONCLUSIONS
  These results suggest that differences in age and weight do not attenuate the Köhler effect in exergames and may even strengthen it.
authors.affiliation: 1 Michigan State University , East Lansing, Michigan.
authors.forename: Samuel T
authors.initials: ST
authors.lastname: Forlenza
authors.affiliation: 1 Michigan State University , East Lansing, Michigan.|2 University of Kent , Canterbury, United Kingdom .
authors.forename: Norbert L
authors.initials: NL
authors.lastname: Kerr
authors.affiliation: 3 Kansas State University , Manhattan, Kansas.
authors.forename: Brandon C
authors.initials: BC
authors.lastname: Irwin
authors.affiliation: 1 Michigan State University , East Lansing, Michigan.
authors.forename: Deborah L
authors.initials: DL
authors.lastname: Feltz