The Köhler Effect: A Motivational Strategy for Strength and Conditioning : Strength & Conditioning Journal

Journal Logo


The Köhler Effect: A Motivational Strategy for Strength and Conditioning

Hill, Christopher R. PhD

Author Information
Strength and Conditioning Journal 41(5):p 90-95, October 2019. | DOI: 10.1519/SSC.0000000000000475
  • Free



Strength and conditioning (SC), personal training, and rehabilitation domains increasingly are using the potential benefits of groups for both behavioral and financial reasons (1). However, when working with clients or athletes in group settings, it is important to consider the role social influence might have in diminishing or strengthening motivation. Previous reviews of the literature have noted increases or decreases in motivation can occur solely based on the ways in which tasks are implemented and groups are designed (10). The literature in social sport and exercise psychology has (by quantity of articles) many more research findings that provide evidence about effort losses in groups (20). However, a more recent line of research has examined how those motivation losses can be turned into motivation gains. The purpose of this article is to examine how the Köhler motivation gain effect can be harnessed to provide enhanced motivation for athletes and clients in SC and group training settings. The research included in this review has been conducted with college and adult populations. Therefore, the implications of the findings presented within this article should be interpreted with caution for SC coaches working in other settings.


In the 1920s, an industrial psychologist named Otto Köhler was noticing something interesting about the power of social influence while rowers of the Berlin Rowing Club were training. Köhler had rowers participate in a biceps curl task in different situations; working alone, working in pairs, or working in groups of 3. When working alone, the rowers curled a 44-kg weight until exhaustion. When in groups, they either used an 88-kilogram bar (for pairs) or a 132-kg bar (in a group of 3 people), again, until exhaustion. The purpose of the increase in weight on the bar was so the amount of weight being lifted by 1 individual never changed. However, when working in groups, if 1 person stops lifting the weight because they become too fatigued, their partner (or 2 other group members) would be unable to continue with the group task because they could not lift the heavy weight on their own. This type of task later became known as a conjunctive task (18). In a conjunctive task, the group outcome is dependent on the performance of the weakest team member. What Köhler noticed was in these conjunctive tasks, the weakest group member worked harder compared with when they worked by themselves (12). This motivation gain became known later as the Köhler effect.

Köhler noted this performance improvement in group settings was a fairly consistent phenomenon and generalized to many of the rowers who were engaged in this conjunctive task. To further understand this phenomenon, he modified the discrepancy for the weaker and the stronger team members. After some refining, Köhler noted this increase in performance was optimized whenever the discrepancy between the weaker and stronger members was moderate (20–40% difference in capabilities; (12)). Because of issues with research dissemination and language differences, Köhler's work went largely unnoticed for decades.

The resurgence of Köhler effect research is important because for many decades, there was a narrative about groups potentially hindering performance. This narrative was driven by researchers who uncovered that as the size of a group increased, the group productivity actually decreased (20). This negative group effect was known by 2 names, the Ringelmann effect or social loafing. Through a variety of group-based experiments, Ringelmann uncovered when group size increases, the group has productivity losses that are mainly due to a lack of an ability to accurately obtain an individual performance score and coordination losses within the group (20). The Köhler effect seems to alleviate both of these issues in group settings because the individual has their own performance (i.e., they cannot hide their own score within the score of others) and there is no identifiable way to lose coordination when performing by oneself toward a team goal where each individual also gets his/her own score. Therefore, Witte (20) noted the Köhler effect is the “anti-Ringelmann” effect and should be used as a way to actually boost motivation in group settings instead of trying to cut your losses in group tasks.

Recently, there has been an increase in research examining the Köhler effect specific to the sport and exercise field. The next section will examine the theoretical explanations for why this effect is seen in group settings. The subsequent section will examine the research already conducted in exercise settings examining motivation gains in group settings. Finally, this article will conclude with practical implications for harnessing the Köhler effect in SC and personal training settings.


Researchers in a variety of psychological domains have examined the Köhler effect and have uncovered 2 potential mechanisms that might be driving the motivation gain seen in group settings. The first mechanism is called upward social comparison (11). In upward social comparison, the weaker team member would need to be paired with a stronger team member if you are trying to boost the motivation of the weaker team member. For example, if you are designing a paired strength training program for a team, it would be wise to pair an athlete who might need a motivational boost with someone who is moderately stronger than the athlete needing the extra motivation. There is some evidence the upward social comparison mechanism, by itself, would bolster the motivation of weaker group members (11).

The second mechanism of the Köhler effect relies on each group member's scores being indispensable to the team score (11). This group indispensability principle can be seen in a variety of tasks, including the original research conducted by Köhler. In the original Köhler studies (12), when the weakest member of the team quit the biceps curl task, the weight was too heavy for anyone to lift it on their own. Another way to think about indispensability is within the context of relay races. The overall team score of a relay race is largely dependent on each member of the team participating at a high level. If 1 group member performs at a suboptimal level, there will be consequences for the entire group's performance. Indispensability is key when thinking about who is the “weak link” in a group. Designing training programs with this indispensability mechanism in mind would likely lead to increases in effort, especially for the weak link in group settings. The indispensability phenomenon has been seen in Köhler effect findings in and out of sport and exercise settings (2,11).

The examples provided in the past 2 paragraphs provide some evidence of 2 key underlying mechanisms that might lead to group motivation gains. However, for it to be a true Köhler effect finding, it needs to consider both components together. Each component by itself might provide some benefit to the motivation of athletes or clients with whom you are currently working with, but both mechanisms together are indicative of current thinking about the Köhler effect.


When thinking about ways to implement the Köhler effect in strength training, coaches should consider how the task structure might influence motivation. Tasks can differ based on the demands placed on the group and how the group is evaluated (18). A conjunctive task is a task when the group score is dependent on the weakest group member (6,18). If a dyad is under conjunctive task domains, and 1 member completes 25 reps of a biceps curl task and the other member of the group completes 32 reps of a biceps curl, the team score would be 25 reps. An additive task is when the performance of the group is a sum of all the group members' contributions to the task (18). Common relay races (i.e., track and field, and swimming) fit the scope of additive tasks. In the weightlifting example presented above, the additive team score would be 57 reps. A disjunctive task is when the best member of a group determines the overall group performance (18). Using the aforementioned weightlifting example, the team score in a disjunctive task would be 32 reps. Finally, a group can also be in a coactive task. In a coactive task, the individuals present are not in a defined group that will have a singular group score, but the 2 individuals will be working toward an individual score in the presence of another person. In the previous weightlifting example, the individuals would just receive their own scores and would not receive a team score. Based on the current state of the literature, if an SC program is using groups to attempt to boost motivation, it is not advisable to use a disjunctive or coactive group setting (2,11).


Although Köhler's original work was using a physical task with athletes, more contemporary work in the field moved away from the intense physical nature of a very heavy biceps curl. Many experiments used tasks such as holding a small weight at a 90° angle from the torso like a static shoulder lateral raise. If the weight fell below 90°, the experiment would stop (6). Although the previously mentioned task is physical in nature, it will likely not bring about changes in strength that fitness professionals aim to target in their conditioning and training sessions.

The studies that are going to subsequently be discussed all have a similar task structure. Participants perform the first set of exercises by themselves to gather baseline data, then participants complete the set of exercises again but in the condition he/she was randomized into (2,8,9). This fact is worth noting because the participants would be fatigued heading into the second set of exercises, potentially limiting their performance. If incorporated into their coaching sessions, SC coaches can expect to see increases in performance especially when athletes or clients are already fatigued.

In the first laboratory experiment, Feltz et al. (2) examined whether the Köhler effect could effectively increase the duration of a 5-plank exercise bout when working with a prerecorded partner under different task demands. The prerecorded partner was a confederate, so the participant in the study would never plank longer than the prerecorded video partner (but the participant did not know this information). Participants either worked in a coactive, additive, conjunctive, or individual task structure. Overall, participants worked harder when paired with a partner, than if they worked by themselves. Interestingly, the conjunctive condition did not perform significantly better than the additive or coactive conditions (2). Practically, in this experiment, participants in the partnered conditions had a 24.1% increase in the planking duration in the second set of exercises. Even after a fatiguing exercise bout, participants worked harder in the second set of exercises when working with a video recorded partner. It is also worth noting previous research findings denote when the partner is physically present, the Köhler motivation gain is enhanced (7,13). SC coaches can not only view this finding as a way to boost motivation, but also a cautionary tale. It might not be helpful for athletes who need a motivational boost to train on their own because the social influence of another person being present, either physical or virtual, seems to boost exercise effort and persistence in an exercise task under conjunctive task demands.

Shortly after the first contemporary experiment, researchers aimed to understand whether the Köhler effect could be harnessed in promoting aerobic exercise (8). Participants were asked to cycle at an intensity to generate 65% of maximal heart rate for as long as they wanted. The participants were randomized into either an individual control condition (with no partner), a conjunctive condition, or a coactive condition. On average, the conjunctive condition participants cycled for 12 minutes longer than the individual control condition and 18 minutes longer than the coactive condition. These findings again lend support that the Köhler effect can be harnessed to bring about increased performance in exercise and fitness settings (8).

Since these original 2 findings, there has been a continued interest in understanding the Köhler effect in exercise settings. One interesting question surrounded the amount of discrepancy that can lead to increased motivation. Köhler's original work indicated a moderate discrepancy, but further refinement of the discrepancy level could lead to increases in the motivational mechanisms (12,19). Presumably, if an athlete is too far inferior or superior to a teammate, the same motivation gains would not be seen. Feltz et al. (3) examined this issue by creating 3 different partners to test against an individual control. All the partners in this experimental manipulation were conjunctive in nature, but the discrepancy between the participant and the partner varied. There were low-discrepancy (1% better performance from the virtually presented partner), moderate-discrepancy (40% better performance than the virtually presented partner), and high-discrepancy (100% better performance than the virtually presented partner) partners. All partnered conditions outperformed the individual control conditions, consistent with previous findings in the Köhler literature (2), but the moderate-discrepancy condition outperformed the low- and high-discrepancy conditions. This finding is consistent with the original Köhler work (12) noting a moderate discrepancy is best at garnering the highest increase in work in exercise settings. When pairing teammates to work together, SC coaches should consider pairing the weaker team member with someone who is about 20–40% stronger than them to see the largest motivation gains. Perhaps, a driving force in this discrepancy is the predictions outlined by self-efficacy theory. If team members are too dissimilar, they likely will not make the comparisons with the partner. The weaker member will believe they have little in common with stronger partner, and the ties between the 2 (both socially and performance wise) will not be as strong. It is important for coaches to remember this discrepancy does not have to be perfect to see changes in motivation for the weak link in these groups, as noted in the previously mentioned study (3). Athletes are going to differ from lift to lift, but keeping the tasks structured as either conjunctive or additive will likely lead to motivation and performance gains for each member of the group compared with using individual tasks. The key is to make sure each individual's performance is uniquely identifiable while keeping an overall team score component.

Researchers have continued to try to uncover mechanisms and variables that will moderate and potentially bolster the Köhler effect in fitness settings. There have been investigations conducted attempting to uncover the role encouragement has in the Köhler effect. In other words, will the superior partner giving a participant encouragement enhance the motivation gains already established in laboratory settings? Participants in a plank study were either given no feedback or verbal feedback from their partner (i.e., “you can do it,” “stay strong here,” and “you got this”). Initial evidence suggests encouragement from a virtually presented partner will actually hurt the Köhler effect by reducing the effort substantially (9). However, later research examined whether changing the pronoun used in the verbal communication (from “you” to “we”) could reverse the negative effects of encouragement seen in the study by Irwin et al. (9). The researchers tested this change because partner-inclusive feedback will likely bolster feelings of team perception and group cohesion (14). Similar to the Irwin findings, Max et al. (14) found the no feedback condition performed better than the other groups, but the inclusive (“we”) encouragement performed better than the exclusive (“you”) encouragement. SC coaches should encourage athletes to use inclusive language within their workout teams to boost perceptions of “we-ness” rather than “I-ness”.

The Köhler effect has also been tested using a variety of other moderators to the relationship, mostly examining how we can change the partner characteristics to boost motivation in exercise settings. Samendinger et al. (16) tested partner similarity in a sample of obese adults (i.e., lighter weight or same weight partners) and did not find weight status of the partner influenced the Köhler effect. Other researchers have examined the role of software-generated partners in exergame-like settings and found the Köhler effect can still be harnessed when working with a software-generated partner (4), but the feedback given from the software-generated partner should be accurate and must be perceived as real by the participants (17). The Köhler effect can also be modified by creating competition with outgroups. If an SC coach has 2 athletes working toward a team score in a conjunctive task while strength training (team 1), the coach could say team 1 is also competing against another team, team 2. In this case, the coach has created a situation where there might be a Köhler effect seen due to the conjunctive nature of the task, but there might a potential boost in motivation because there are additional mechanisms outside of the group now motivating the individuals in each group to not let their partner down. Recent evidence outlines outgroup competition (having multiple teams attempting to score higher than their competitors) in physical tasks will also provide enhanced motivation compared to just working with a partner or working without a partner (15). Although not yet tested, practitioners would likely see this improvement in motivation for athletes and exercisers who have a more competitive nature.

A major concern of being the inferior partner in a dyad might lead to decreases of motivation over time. However, researchers have extended the Köhler motivation gain to lengths over a 6-month period (5). It appears in longer studies the Köhler motivation gain still holds over long periods. One hypothesis is the weaker team member starts to take ownership of their role as the determining factor for the group. Therefore, the weaker member will consistently work a higher level in conjunctive groups and by themselves.

There are many future research questions that need to be addressed in the Köhler motivation gain. One main concern is what happens to the motivation of the stronger members of the groups in conjunctive task settings. As of right now, there is no evidence in exercise settings of what happens to the stronger individual in these group settings. However, it would be an interesting future line of inquiry, and coaches should be thoughtful about how they work with the athlete who is consistently the stronger member in a group. Coaches could apply the lessons from other leading motivational theories (e.g., self-efficacy theory, self-determination theory, and achievement goal theory) to help maintain high levels of motivation in their stronger athletes. Specifically, self-efficacy theory and self-determination theory (competence, autonomy, and relatedness) focus on how the most confident performers can continue to have an upward spiral of performance and motivation as they continue to strengthen their strengths. Also, coaches could discuss with the strongest athletes that their role is to be a team leader in the weight room, and as part of their role, they need to continue to work at high levels, so other athletes maintain their levels of effort. This leadership role is one way for athletes to take ownership of their own training in a positive direction and could lead to more feelings of relatedness within a self-determination framework. An additional avenue for future research would be understanding if there are developmental differences in Köhler effect findings. No work to date has examined the Köhler effect with youth or high school populations, but it would be helpful to understand those relationships for SC coaches working with younger athletes.


The previous section and other reviews of the literature (19) demonstrate the Köhler effect could provide SC coaches, personal trainers, and practitioners in the health sciences with a potential mechanism to boost motivation in their respective professional spheres. The first key point in maintaining high levels of motivation in group settings is practitioners should make sure individual contributions in groups are quantifiable and easily measurable. In each of the tasks mentioned in the review, each member of the group was given feedback about their own performance, the performance of the teammate, and the overall group performance. When feedback is just given at the group level (i.e., just a group score for a collection of people), it allows for others to socially loaf and not put forth as much effort as possible (10). Training in group settings is common in the SC field; therefore, thoughtful group design can lead to performance improvements of the weaker members of the group rather than social loafing. SC coaches should also consider the amount of discrepancy between group members. As noted in the discrepancy study, having the weaker team members being moderately discrepant (20–40%) from the stronger group members seems to provide a motivation gain that is substantially better than a lower or higher discrepancy partner (3). If a coach is setting up groups and is looking to boost the effort of the weakest member of the group, it is important to consider the Köhler motivation gain is most effective when the weaker member of the group is about 20–40% discrepant from the stronger member of the group.

Based on the current literature, SC coaches should look for unique ways to create conjunctive task structures with their teams. Potentially, just by grouping members together and telling them the group will be given a team score that is based on the weakest member of the group can improve performance by itself (2). Incorporating an outgroup can further boost the Köhler motivation gain seen in the exercise psychology literature (15). If an SC coach has 20 soccer players and specifically wants to target boosting the motivation of the weakest members of the group in a circuit training style workout, the strength coach could first divide the groups based on the Köhler principles already mentioned above (i.e., creating the proper discrepancy) with about 3–4 players per group, then inform the athletes the team score is the score of the lowest scoring team member in each group and inform each group they are competing against each other. This example would be a way in which SC coaches could use both the Köhler effect and outgroup principles to boost motivation in weaker athletes. SC coaches could also tell the athletes their team scores will be posted and tracked week by week. Over time, this boost in motivation could help develop the weaker members of the teams to become stronger athletes. It is critical to note this boost in motivation seems to hold over time and continually being the weaker member does not seem to hurt participants' motivation (14).

SC coaches can also use each of the mechanisms of the Köhler effect in solitude and likely see an enhanced performance in SC, fitness, and exercise settings. Providing unique ways to have weaker athletes or clients upwardly socially compare while maintaining a conjunctive task structure will lead to the strongest motivation gains. The Köhler effect has robust research evidence providing explanations for how weaker members of groups function within conjunctive task structures. The motivation gains seen in the laboratory can be nicely translated to professional settings to boost improvements of the weakest members, especially in SC settings.


  • Have athletes train in groups using conjunctive task structures (i.e., the group score is the weaker team member's score but both members' scores are identifiable).
  • Inform the stronger athletes of their role in motivating the weaker athletes. This strategy will likely lead to greater role acceptance and a continued high level of effort in group tasks for both the stronger and weaker athletes.
  • Communicate athlete roles using an autonomy-supportive approach by providing a rational for their role on the team/purpose of the training, provide feedback that is constructive and solution focused, inquire about athlete perceptions of the task/role, and encourage athletes to accept responsibility of their training.
  • Coaches can also focus on developing relatedness-supportive environment during training. Relatedness-supportive environments are characterized by interpersonal communication that has components of openness, respect from the coach, support, and warmth.
  • When working with athletes, encourage them to use inclusive language (we-ness) rather than exclusive language (I-ness).
  • Create a culture of outgroup competition and have different teams compete under conjunctive demands against each other to boost the Köhler motivation gain.
  • Try to have the weaker athlete stay at the 20–40% discrepancy, but do not worry if it is not perfect. Working in conjunctive tasks with other teammates will lead to great effort in tasks compared with working individually.
  • Incorporate the findings from other theories of motivation (i.e., self-determination theory and self-efficacy theory) to continue to boost the motivation of the stronger athlete.
  • Make sure the individual performance of each athlete is identifiable. Without this individual component, social loafing is likely to occur and motivation decrements will follow.
  • Always reinforce the importance of the SC training in respect to the overall goal of the team. If the task is perceived as meaningless, social loafing is likely to occur.
  • When athletes are not in season and away from teammates, coaches can encourage athletes to communicate with each other about how their offseason training is progressing. Coaches can set up a social media message board where athletes can post their daily workouts (with relevant performance measures) and teammates comment on their teammate's workouts. Providing space for athletes to engage with their teammates could lead to better adherence to off-season training programs and increase cohesiveness of the team.


The author thanks the Institute for Child Development and Family Relations and the Faculty Center for Excellence for supporting the publication of this article with funded writing time.


1. Escalante G, Escalante M. Small group training to maximize results for clients and profitability. Person Train Quart 5: 8–10, 2018.
2. Feltz DL, Kerr NL, Irwin BC. Buddy up: The Köhler effect applied to health games. J Sport Exerc Psychol 33: 506–526, 2011.
3. Feltz DL, Irwin BC, Kerr NL. Two-player partnered exergame for obesity prevention: Using discrepancy in players' abilities as a strategy to motivate physical activity. J Diabetes Sci Technol 6: 820–827, 2012.
4. Feltz DL, Forlenza ST, Winn B, Kerr NL. Cyber buddy is better than no buddy: A test of the Kohler motivation gain effect in exergames. Games Health J 3: 98–105, 2014.
5. Feltz DL, Ploutz-Snyder L, Winn B, Kerr NL, Pivarnik JM, Ede A, Hill CR, Samendinger S, Jeffery W. Simulated partners and collaborative exercise (SPACE) to boost motivation for astronauts: Study protocol. BMC Psychol 4: 54, 2016.
6. Hertel G, Kerr NL, Messé LA. Motivation gains in performance groups: Paradigmatic and theoretical developments on the Köhler effect. J Pers Soc Psychol 79: 580–601, 2000.
7. Hertel G, Niemeyer G, Clauss A. Social indispensability or social comparison: The why and when of motivation gains of inferior group members. J Appl Soc Psychol 38: 1329–1363, 2008.
8. Irwin BC, Scorniaenchi J, Kerr NL, Eisenmann JC, Feltz DL. Aerobic exercise is promoted when individual performance affects the group: A test of the Kohler motivation gain effect. Ann Behav Med 44: 151–159, 2012.
9. Irwin BC, Feltz DL, Kerr NL. Silence is golden: Effect of encouragement in motivating the weak link in an online exercise video game. J Med Internet Res 15: e104, 2013.
10. Karau SJ, Williams KD. Social loafing: A meta-analytic review and theoretical integration. J Pers Soc Psychol 65: 681–706, 1993.
11. Kerr NL, Messé LA, Seok DH, Sambolec EJ, Lount RB, Park ES. Psychological mechanisms underlying the Köhler motivation gain. Pers Soc Psychol Bull 33: 828–841, 2007.
12. Köhler O. Kraftleistungen bei Einzel- und Gruppenarbeit (physical performance in individual and group work). Ind Psychotech 3: 274–282, 1926.
13. Lount RB, Park ES, Kerr NL, Messé LA, Seok D. Evaluation concerns and the Köhler effect: The impact of physical presence on motivation gains. Small Group Res 39: 795–812, 2008.
14. Max EJ, Samendinger S, Winn B, Kerr NL, Pfeiffer KA, Feltz DL. Enhancing aerobic exercise with a novel virtual exercise buddy based on the Köhler effect. Games Health J 5: 252–257, 2016.
15. Moss O, Feltz DL, Kerr NL, Smith AL, Winn B, Spencer BD. Intergroup competition in exergames: Further tests of the Köhler effect. Games Health J 7: 240–245, 2018.
16. Samendinger S, Forlenza ST, Pfeiffer KA, Feltz DL. Partner weight as a moderator of exercise motivation in an obese sample. Med Res Arch 3: 1–13, 2015.
17. Samendinger S, Hill CR, Kerr NL, Winn B, Ede A, Pivarnik JM, Ploutz-Snyder L, Feltz DL. Group dynamics motivation to increase exercise intensity with a virtual partner. J Sport Health Sci, 2018 [Epub ahead of print].
18. Steiner ID. Group Process and Productivity. New York, NY: Academic Press, 1972. pp. 14–33.
19. Weber B, Hertel G. Motivation gains of inferior group members: A meta-analytical review. J Pers Soc Psychol 93: 973–993, 2007.
20. Witte EH. Köhler rediscovered: The anti-Ringelmann effect. Eur J Soc Psych 19: 147–154, 1989.

motivation; psychology; teams

Copyright © 2019 National Strength and Conditioning Association