Effects of long-term competition upon adult behaviour

Abstract

Recent findings have shown that group-reared rats were more dominant in adulthood than those raised individually. This difference was predicted as being due to the fact that group-reared rats did better in competition because of their early competitive experience whereas the solitary-reared animals lacked such early competitive training. In the present experiment,thirty-two male rats were divided into two groups, one (experimental) exposed to competitive and the other (control) to noncompetitive conditions. In the competitive condition rats had to compete for water daily for 70 days. The purpose of the present investigation was to determine whether competition in early life does result in rats acquiring greater skill and practice in competing i.e. whether experimental (‘competing') rats are more dominant in adulthood than the control ( ‘noncompeting') individuals. Dominance was measured by pairing each 'competing’ S once with every ‘noncompeting’ S in a series of two-minute competitive drinking situations. The findings showed that neither the ‘competing' Ss developed greater skill and practice in competing nor did they show dominant behaviour towards the ‘noncompeting’ Ss. Other findings have also made predictions regarding these two groups of animals: ‘competing' Ss were expected to be less emotional', more active and exhibit more locomotor behaviour. They should be less sociable and have heavjer adrenal weights. Four more measures were then used to test the above hypothesis. Two activity measures showed 'competing’ Ss neither less ‘emotional' nor more active or exhibiting more locomotor behaviour than the 'noncompeting' Ss. One of the two sociability measures revealed that ‘competing' animals were more sociable than the 'noncompeting’ animals. The adrenal weights of the ‘competing' animals were not signific­antly heavier than the ‘noncompeting’ animals. All these findings suggest that competition elicited only a mild or short-term effects on the behaviour of animals.