in these circumstances. Online communities and groups Research regarding social loafing online is currently relatively sparse, but is growing. A 2008 study of 227 undergraduate and graduate students enrolled in web-enabled courses at the Naval War College (NWC) and a public university found that social loafing not only exists, but may also be prevalent in the online learning classroom. Although only 2 percent of NWC and 8 percent of public university students self-reported social loafing, 8 percent of NWC and 77 percent of public university students sensed that others engaged in social loafing. Additional findings generally verify face-to-face social loafing findings from previous studies. The researchers concluded that injustice in the distribution of rewards increases social loafing, and suggest that self-perceived dominance negatively affects individual participation in group activities. Social loafing, also known as "lurking", greatly affects the development and growth of online communities. The term social loafing refers to the tendency for individuals to expend less effort when working collectively than when working individually. This phenomenon is much like people's tendency to be part of a group project, but rely heavily on just a few individuals to complete the work. Generally, social loafers regularly follow the discussions and content of online communities, but choose not to expand on posts or add to the knowledge of the community. Additionally, participation in online communities is usually voluntary; therefore there is no guarantee that community members will contribute to the knowledge of the website, discussion forum, bulletin board, or other form of online engagement. Lurkers are reported to constitute over 90 percent of several online groups. The main reason people choose not to contribute to online communities surprisingly does not have to do with societal laziness, but in fact the potential contributors belief that their entries will not be taken seriously or given the credit that they deserve. When people assess the risks involved in contributing to online communities, they generally avoid participation because of the uncertainty of who the other contributors and readers are and the fear of their work being undervalued. Age-related effects on participation Although studies justify the notion that people often do not contribute to online communities, some research shows that older adults are more likely to participate in online communities than younger people because different generations tend to use the internet differently. For example, "older adults are more likely to seek health information, make purchases, and obtain