Academic journal article Psychologische Beiträge

Revisiting the Kohler Effect: Does Diversity Enhance Motivation and Performance in Groups?

Academic journal article Psychologische Beiträge

Revisiting the Kohler Effect: Does Diversity Enhance Motivation and Performance in Groups?

Article excerpt


Based on systematic experimental research, we explore in this chapter whether increases in group performance might be a function of diversity in group members` capabilities, and how aspects of this group diversity can be used to produce "synergy" in teams. After a short review of experimental research on motivation gains in groups, we particularly focus on the "Kohler effect" that (a) demonstrated conditions under which group members were motivated to exert more efforts for their group than under individual working conditions, and (b) suggested that these motivation gains only occurred when coworkers differed moderately in their abilities. After discussing results of Kohler's original work (1926, 1927) and possible explanations, we describe two recent studies that replicated essential features of Kohler's paradigm in a more controlled setting. Results demonstrated reliable performance gains in groups only under conjunctive task conditions, suggesting that perceived instrumentality of own contribution for the group outcome is an important factor to understand synergetic processes. However, no moderation of these performance gains by group diversity was found, demonstrating that these effects can be more general than Kohler (1926, 1927) assumed. The implications of these results for applied questions are discussed.

Key words: group performance, motivation gains, synergy, diversity, Kohler effect


Diversity certainly is a potential challenge for working groups. For instance, differences among individual members' apparent performance capabilities might cause sub-optimal work outcomes as a consequence of increased coordination requirements and/or motivation losses. However, under certain conditions diversity might also produce "synergetic effects," outputs that are higher than what might be expected based on the individual performance capabilities of their members. According to a simple working definition, synergy occurs when process gains in a group (relative to individual performance) are higher than process losses (see also Stumpf in this issue). Although the notion of synergy is quite popular and has been discussed in a variety of areas including the group research literature, surprisingly little is known about the psychological process of synergy and the preconditions that are necessary to produce synergetic effects.

One step towards a better understanding of synergetic effects is to explore conditions that produce process gains in groups. And, it seems rational to first explore rather simple settings where the analysis of the relevant psychological processes is easier than in complex situations. Thus, in contrast to most other papers in this issue, we operationalized diversity in groups in a very basic sense as the discrepancy of group members on only one single dimension, the capability to perform a simple physical task. Moreover, we explored process gains in ad hoc groups with the smallest possible group size of two members (Forsyth, 1990). Finally, since we are mainly focusing on motivational rather than cognitive effects (i.e. problem solving, creativity), we considered persistence tasks in which (physical) performance is directly related to motivation levels. We realize that these limits on the scope of our inquiry might reduce its benefits for understanding synergetic processes in larger groups with more complex tasks, in which participants differ in many aspects and different sub-tasks have to be coordinated. However, we believe that starting with simple settings can provide valuable insights about psychological processes that should also be found in more complex situations, once we know what to look for.

Motivation Gains in Groups

In contrast to the extensive research literature on motivation losses in groups (e.g., Baron, Kerr, & Miller, 1992; Shepperd, 1993; Karau & Williams, in press), relatively few studies have demonstrated that task performance in a group can be higher than that of the same participants when working alone. …

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