Acquisition of probabilities in anticipatory appraisals of stress

Processes involved in predicting stressor events were examined from the perspective of ‘associative memory models’. Subjects were exposed to alphabetic letters which supposedly represented electrical resistors used in audio equipment, in the guise of marketing research. Each letter presentation was followed either by a burst of aversive white noise, signifying ‘resistor failure’ during a brief surge of current, or by a green light, signifying ‘resistor effectiveness’. After a programmed series of presentations, subjects were asked to make several judgments about each resistor; analyses of these judgments focused on the comparative influence exerted by the alternate stimulus events. Regardless of the type of judgment (e.g. probability of future noise, frequency of earlier silent outcomes, and so on), the determining stimulus property was the cumulative frequency of earlier aversive outcomes. Moreover, the dominance of this property was not altered by manipulations designed to elevate the salience of equally relevant benign outcomes. Results were discussed with reference to models of categorical memory and predictive confidence. Circumstances under which stress predictions may be especially inaccurate were considered, as were implications of the present findings for studies of differences in categorical-frequency memory processes associated with ‘depresed mood’.