Booth, C. L. (1973). Early social experience and gregariousness in the rat. Developmental Psychology, 8(3), 360-368.
http://dx.doi.org/10.1037/h0034321
Exposed a total of 220 Long-Evans hooded rats, in 2 experiments, to 3 social environments: (a) maternal deprivation for 8 hrs/day or continuous presence of the mother, (b) presence of litter mates or no litter mates, and (c) adult group housing or isolation housing. At weaning, and in adulthood, male-female pairs were tested for amount of time in physical contact in an open field. Group rearing, followed by adult isolation, produced the most gregariousness in adulthood, and isolation rearing, followed by adult grouping, produced the least. Continuous grouping or isolation produced an intermediate amount of interaction. Maternal treatment had little effect upon gregariousness. It is hypothesized that an optimal level of social stimulation is established in infancy. The magnitude of the effect of adult housing on gregariousness is determined by this optimal level. (29 ref.) (PsycINFO Database Record (c) 2016 APA, all rights reserved)