Contextual aspects of other animal stress cues in avoidance acquisition.
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
Fear or stress cues are considered to be important in evolutionary survival. Hence, such cues are likely to be important and powerful in inter-animal interactions. In aversive situations animals should be maximally attuned to cues providing information about the safety or danger of various elements of their environment. The present series of experiments with albino rats studies the inhibitory effect on avoidance acquisition of the presence of a stressed (shocked) model animal in the safe chamber of a hurdle-jumping apparatus. Three main theories are considered: (a) that because the model receives inescapable shock, a process of vicarious instigation of helplessness leads to inhibition of avoidance acquisition; (b) that increased arousal produced by the shocking of a model adds to the already high arousal of the subject, leading to decreased performance; and (c) that situational cues provided by the stressed model modify the perception by the test animal of the safety or danger of environmental elements. The results of the experiments support neither the vicariously instigated helplessness nor the increased arousal hypotheses. Rather the subject appears to be using situational cues provided by the stressed model within the context of the safe/dangerous environment. Further, evidence that the inhibitory effect occurs, though not as strongly, when the model is shocked in a third chamber in line with the safe chamber in a one-way avoidance task and also in two-way shuttle avoidance suggests that the nature of the situational information comes from directional rather than place cues. The results are discussed in terms of cognitive theories of avoidance.