Play soliciting behavior in prepubertal and postpubertal male rats

Pre- and postpubertal play soliciting behavior was observed in intact males, castrate males, sham-operated males, and female controls. Although play soliciting decreased markedly with age in all groups, male treatment groups did not differ reliably on pre- or postpubertal tests. Males, however, engaged in reliably greater play soliciting than females on all measures in both preand postpubertal tests. These results suggest that the major decrease in social play associated with the attainment of sexual maturity is apparent in the play soliciting behavior of both sexes and may be attributed to maturation effects other than that associated with gonadal hormones. The results are discussed in reference to organizational and activational effects of male gonadal hormones on measures of social play behavior.     

Vocalization as an objective measure of shock-elicited social aggression in rats

Intense vocalizations emitted by pairs of shocked rats were compared when physically separated by a transparent partition and when free to engage in social aggression. Greater vocalization occurred in the free-access condition and was positively correlated with visually observed attack scores in pairs that had prior experience with shock. A second experiment determined the influence of repeated fighting exposures upon the correlation between observed attack and vocalization. High positive correlations were obtained after initial sessions within a broad range of intermediate fighting. At high and low extremes of fighting, correlations were nonsignificant. The results are discussed with reference to restriction imposed upon variation of attack scores based upon standard criteria of observation.