structural:reformatting, stylistic:style_transfer, quality:correction, linguistic:voice_change, information:filtering
Dispersal and transformation

Two or more people in interacting situations will over time develop stable territorial relationships. As described above, these may or may not develop into groups. But stable groups can also break up in to several sets of territorial relationships. There are numerous reasons for stable groups to "malfunction" or to disperse, but essentially this is because of loss of compliance with one or more elements of the definition of group provided by Sherif. The two most common causes of a malfunctioning group are the addition of too many individuals, and the failure of the leader to enforce a common purpose, though malfunctions may occur due to a failure of any of the other elements (i.e., confusions status or of norms).

In a society, there is a need for more people to participate in cooperative endeavors than can be accommodated by a few separate groups. The military has been the best example as to how this is done in its hierarchical array of squads, platoons, companies, battalions, regiments, and divisions. Private companies, corporations, government agencies, clubs, and so on have all developed comparable (if less formal and standardized) systems when the number of members or employees exceeds the number that can be accommodated in an effective group. Not all larger social structures require the cohesion that may be found in the small group. Consider the neighborhood, the country club, or the megachurch, which are basically territorial organizations who support large social purposes. Any such large organizations may need only islands of cohesive leadership.

For a functioning group to attempt to add new members in a casual way is a certain prescription for failure, loss of efficiency, or disorganization. The number of functioning members in a group can be reasonably flexible between five and ten, and a long-standing cohesive group may be able to tolerate a few hangers on. The key concept is that the value and success of a group is obtained by each member maintaining a distinct, functioning identity in the minds of each of the members. The cognitive limit to this span of attention in individuals is often set at seven. Rapid shifting of attention can push the limit to about ten. After ten, subgroups will inevitably start to form with the attendant loss of purpose, dominance-order, and individuality, with confusion of roles and rules. The standard classroom with twenty to forty pupils and one teacher offers a rueful example of one supposed leader juggling a number of subgroups.

Weakening of the common purpose once a group is well established can be attributed to: adding new members; unsettled conflicts of identities (i.e., territorial problems in individuals); weakening of a settled dominance-order; and weakening or failure of the leader to tend to the group. The actual loss of a leader is frequently fatal to a group, unless there was lengthy preparation for the transition. The loss of the leader tends to dissolve all dominance relationships, as well as weakening dedication to common purpose, differentiation of roles, and maintenance of norms. The most common symptoms of a troubled group are loss of efficiency, diminished participation, or weakening of purpose, as well as an increase in verbal aggression. Often, if a strong common purpose is still present, a simple reorganization with a new leader and a few new members will be sufficient to re-establish the group, which is somewhat easier than forming an entirely new group. This is the most common factor.