168 John B. Calhoun 



reduce the emission of signals eliciting social awareness of him by associ- 

 ates. Such signaling may involve other than vocal modes and may even 

 involve reduction of S'-"^ itself. In the end, such reductions of d and S'^"^ will 

 produce an individual which, when encountered, is judged by associates as 

 being dull, lifeless, and with flat affect, lacking the attributes of an appro- 

 priate object for social interaction. 



F. Velocity in High-Density Rat Societies 



While these formulations of social dynamics were being developed I 

 was simultaneously pursuing empirical studies of social dynamics revealed 

 by large groups of domesticated Norway rats. We shall examine those 

 data which indicate (a) that densities greater than appropriate for Nb 

 suppress velocity, and (b) that an increase in vitamin A above normal 

 levels buffers the social system against the velocity-suppressing force of 

 increased density. 



During a 16-month period of 1960-1961 further studies in the habitat 

 (Fig. 33), discussed in Section XII, C, w^ere conducted. In this second series 

 of studies the only habitat change involved altering the method of providing 

 food and water. This change precluded the development of the behavioral 

 sink discussed in Section XII, C. [See Calhoun (1962b) for a general ac- 

 count of these two series of studies.] However, our concern here will be 

 with results not previously presented. 



During the 13th, loth, and 16th months of this study estimates of 

 velocity, v were made for each of the 32 adult males in each of the two 

 societies considered here. All males were fully mature, ranging in age from 

 10 to 15 months of age. 



Procedure for velocity estimation: As illustrated diagrammatically in 

 Fig. 33, each of the four pens in the room defining area A contained two 

 areas w^here social interaction occurred most frequently. One was on top 

 of the elevated artificial burrows; the other was on the floor in the immediate 

 vicinity of the sources of food and water. During each half hour of observa- 

 tion, each rat was given one velocity score for each of the eight locations 

 visited. On 2 days, not more than 3 days apart, Dr. Kyle R. Barbehenn 

 and I each recorded such velocity scores for 16 half-hour periods during 

 each of the three months mentioned above. For a particular month, the 

 estimated velocity thus consisted of the sum of the velocity scores for 32 

 half-hour periods of observation. The estimated velocity, v, is here taken 

 as the mean for three 32 half-hour sums. 



The two societies were designated as lA and 2A. Thirty-two males in 

 lA and 32 males in 2 A survived through the 15th month. A few males died 



