132 John B. Calhoun 



tained established groups of Norway rats in large cages. Despite or because 

 of the existing hierarchy characterizing the group, all rats exhibited rela- 

 tive amicable relations, one to another. All presumably had developed 

 nearly identical target diameters. Introduction of a single alien rat im- 

 mediately produced a state of turmoil within the group, particularly in- 

 tense actions being directed toward the alien by all members of the estab- 

 lished group. In such experiments the ahen rat, the one with the markedly 

 differing target diameter, frequently died within a day or two. This death 

 came, not as a result of wounds received, but as a result of inability to 

 accommodate physiologically to the intense action directed toward him. 

 His df exceeded a threshold compatible with survival. 



Or we may take any one of the several incidents publicized by the press 

 and television during 1960 and 1961 in which "Freedom Riders" engaged in 

 action which challenged the established value systems of certain segments 

 of the socially dominant whites in the Deep South of the United States. 

 Such actions freciuently evoke drastic reaction, including physical \1o- 

 lence, from members of the established group. Furthermore, many cross 

 currents of elevated intensity of interaction became generated within 

 members of the established group as they considered appropriate adjust- 

 ments to the threat to their held values and to their prior target diameter. 



The point I have been making in both the theoretical formulation and 

 in these examples is that a qualitative change in the target diameter of a 

 portion of the group will produce both an increase in n and an increase in 

 intensity of interaction. Another pertinent example is one I have previously 

 given (Calhoun, 1956, pp. 87-88). That example concerns the establish- 

 ment of a new group, designated as "C57 Colony IB," from two smaller 

 groups of mice not previously having contact with each other. After pro- 

 vision of an access door through the wall previously separating the two 

 groups, the males from the socially more integrated group invaded the 

 living space of the other males. Not only did the former attack the latter, 

 but the males from the more socially integrated group began a period of 

 intense fighting among themselves such as had never previously been 

 observed. 



Admittedly, all three of these examples include introduction of aliens 

 into an established group rather than the hypothesized divergence in 

 target diameter of a portion of a single group. However, it is difficult to 

 imagine a portion of a group altering their target diameter without tempo- 

 rary partial isolation from the remainder. So, in effect, the consequences 

 of divergence of target diameters among members of a group will be the 

 same regardless of how the group is assembled. 



In actuality 



M = {Sv/A) (101) 



