Loafers and free riders are allowed to benefit because, in each case, the outcome of group performance .. is shared equally by all group members, regardless of their input.  (Weldon and Mustari, 1988, p. 331)

That is, in group situations where successful accomplishment of work confers equal rewards on each member, a member who does not perform maximally will reap the same extrinsic rewards as fellow group members who do.

Perceived Lack of Potential for Evaluation of One's Contribution

• Olson (1065) posited that individuals reduce their contributions to endeavors in larger collectives because their efforts are not noticeable to others.

Perceived Dispensability of Effort

• Individuals work less as group members than as solo performers because they deem their efforts as dispensable to the group's task accomplishment.  ... they feel that as the performance unit grows, their input becomes less necessary to do the job.

Perceived Lack of Influence over Task Outcomes

• Whereas perceived dispensability may be interpreted as one's belief that the group does not require one's efforts and that the group will complete its task at some minimal satisfactory level even without one's personal contributions, a perceived lack of influence refers to one's belief that the group will not achieve a certain desired level even with one's efforts -- that no matter how high the caliber on one's contributions, the group will still fail to reach its goal.

Perceived Loafing by Other Group Members

• The perception that one's fellow group members are loafing may increase the likelihood of one's own loafing.
• Viega reported that group members who believe their co-workers are "generally unwilling to commit themselves to accomplishing the task at hand" will reduce their own contributions to the tasks (1991, p.882)
• It has been proposed that people reduce their own contributions in groups because they wish to avoid being taken advantage of by group members who loaf while they contribute.  (Sucker role)
• Kerr (1983) ... individuals are more likely to loaf if their able coworkers loaf over time.

Individualism vs. Collectivism

• Individualistic societies emphasize the achievement of personal goals over group goals, whereas collectivists are acculturated to put group goals before their own self-interests.  Whereas collectivists may feel responsible and necessary for group success and believe their like-minded fellow group members will similarly pull their weight, less group-oriented individualists may be more likely to loaf.

Unmotivating Task

• Research indicates that loafing declines if group members are performing motivating work.

Perceived Group Performance Problems

• In a group where nothing seems to click, the feedback of this troubled status may contribute to one's loafing by reducing one's sense of  influence over task outcomes.
• Individual group members who receive feedback that their group is performing poorly expect their group will also perform poorly on a similar task in the future. (Tindale, Kulik, and Scott, 1991)

Perceived Relative Task Ability

• It is likely that an individual who perceives he or she is less competent at the task than other group members will have an enhanced sense of being unnecessary for doing the job, as a result of this sense of relative inferiority to others in the group.
• Such perceived dispensability will, in turn, contribute to Social Loafing.
• Research has shown that people will even present themselves negatively if it serves their purposes -- e.g., if they believe a self-glorifying claim will threaten the audience, or if they prefer to avoid excessive public expectations. 
• Thus, people do not merely want to present themselves positively; people aim to accomplish goals, and these goals may involve modest or even unflattering self-representations (Schlenker & Weigold, 1992, p.144)

A Model of Social Loafing in Real Work Groups

It is hypothesized that:

1. Social Loafing in real work groups increases with
   • A wish to avoid the sucker role
   • Perceived lack of influence over task outcomes
   • A wish to avoid appearing too competent
   • Perceived dispensability
   • A wish to avoid appearing incompetent
2. Performing an engaging and meaningful task, as opposed to a boring one with a trivial outcome, will curb loafing.
3. The wish to avoid the sucker role increases with
   • individualism vs. collectivism
   • Perceived loafing by co-workers
4. A perceived lack of influence increases with 
   • Individualism vs. collectivism
   • perceived loafing by co-workers
   • perceived superiority to co-workers at the task
   • perceived group performance problems
5. The wish to avoid appearing too competent increases with the perceived superiority to co-workers at the tasks.
6. Perceived dispensability increases with perceived inferiority to co-workers at the task.
7. The wish to avoid appearing incompetent increases with the perceived inferiority to co-workers at the task.

Recommendations

1. Compose groups in which every member brings a unique set of skills to bear on the task and in which members are at comparable levels at their respective areas of expertise, so as to increase each member's perceived indispensability and perceived influence over successful task outcomes. ... each member's particular area of expertise should be made explicit to alleviate feelings of dispensability.
2. Limit group size to fit the task requirements so that members' efforts are clearly indispensable.
3. Remedy problematic process while it is not yet too late.
4. Give groups greater discretion over planning and executing their work to increase task motivation.