Social dominance in albino rats as a function of the effort variable

Abstract

The experiment was designed to explore the generalizing effect of the effort variable from one set of conditions in which rats were trained to push differentially weighted barriers, to a second experimental setting in which pairs of rats competed in social dominance contests. Fifty-four Sprague-Dawley male rats were divided into three groups: Gp. Heavy (H) Ss were conditioned to a 149-gm. barrier; Ss of Gp. Light (L) were trained in a 30-gm. barrier; Gp. No Contact (NC) animals perceived a visual display of the dummy but no contact was made in the dominance tube. The apparatus consisted of two lucite tubes in parallel position, both tubes connected at each end to a choice box, with an end box attached to each choice area. The lucite tubes were sufficiently narrow so that two rats could not pass one another, therefore requiring the socially dominant animal to force the other from the tube. Pretraining Days 1-15 involved adaptation of the animals to the apparatus and the dummy-barrier. Training Days 1-48 represented a daily sequence of forced-choice trials to the unobstructed tube and dummy tube in counterbalanced order (Trials 1 and 2); Trial 3 was free choice to either tube and Trial 4 was forced choice to the path not selected on Trial 3. Water reward was given on all trials. Test Days 1-24 consisted of a daily series of four trials per rat, in which water-reward trials were alternated with social dominance matching trials against other members of the animal's test group. Eighteen test groups of three members each were formed, with the three treatment conditions represented in each group. The results obtained indicated that (1) no significant preference for either tube was made by Ss of the three treatment conditions throughout Training Days 1-48, and (2) no significant differences between Gps. H, L, and NC occurred in social dominance victories during Test Days 1-24. It was concluded that the present experiment demonstrated no significant generalization effect of the effort variable from training phase to testing phase. Supplementary information regarding spontaneous alternation, levels of social dominance, and correlation of the dependent variables was provided in the Appendix section of the paper.