Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Two major stress sources--imminence of threat and effortful cognitive formulations of predictive judgments appeared to be inversely related during the stress appraisal process. Inter-relationships among stress sources and cognitive and direct reactions were examined using psychometric, behavioural and psychophysiological measures throughout a multistage paradigm which systematically varied stress relevant control and informational factors.;The two initial experiments derived subjective stress, control, and informational ratings for lists of hypothetical situations. Results from both studies delineated individual variations in propensities to report stress. Moreover, perceived stress was negatively associated with control but positively related to informational demands, suggesting an oppositional co-variation between the stress sources. Control was found to be positively related to information demand. Hence, the provision of control appeared to enhance the information demandingness of the situation.;In the third experiment, high and low stress perceivers were presented with situations represented by sets of alphabetic letters which varied in control and informational characteristics. Subjects were required to select those letters which were least associated with aversive event (noise) occurrence.;Behavioural indices were length of reaction time (RT) and subjective noise probability (SP) associated with the letter selection. Overall, behavioural results were consistent with predictions based on the control and informational constraints of the presented situations.;Psychophysiological reactions corresponded to variations of controllability although the patterns of response differed as a function of the index addressed. These findings suggested that the two stress sources were differentially operative, and were discussed in terms of preferences regarding stress negotiations and coping strategies.;Sex differences in psychophysiological reactivity were evident whereby females displayed increased sensitivity to physically threatening and effortful cognitive processing demands while males demonstrated enhanced responding to physical stimuli components. However, sex differences in psychophysiological reactivity were not predicted by subjective reactions to similar stimuli properties. Moreover, individual differences on psychometric stress indices did not correspond to the reactions obtained with direct response measures. Nevertheless, both subjective and direct response reactions appeared to be similarly governed by "commonly" derived appraisals of the situational attributes, i.e., as determined by the controllability parameters of the presented situations.



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