Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Donald A. Williamson


It was the goal of the current study to investigate one debiasing technique and its ability to reduce judgmental errors. In addition, a rival hypothesis of demand characteristics was examined as a possible explanation of any findings of the reduction of judgmental errors. Participants were randomly assigned to either a control group or a debiasing group and asked to rate the likelihood of several hypothetical events in a 2 x 2 x 2 x 2 (Gender x Anxiety Group x Treatment Group x Repeated Measure) repeated measures experimental design. Level of anxiety responsiveness was measured to arrange subjects into a "normal" and a highly anxious group. It was hypothesized that highly anxious participants would report higher probability estimates of future threat-related events relative to participants with a "normal" level of anxiety responsiveness, a main effect for anxiety. Secondly, it was hypothesized that a two-way interaction of treatment group and repeated measure upon threat probability ratings would be found. Third, it was hypothesized that a two-way interaction of gender and anxiety upon threat probability ratings would be found. Finally, it was hypothesized that there would be no main effects or interaction effects involving the repeated measure and the experimental demand independent variable. A mixed factorial design 2 x 2 x 2 x 2 repeated measures ANOVA was conducted using the threat probability ratings as the dependent variable. In addition, two separate analyses were conducted using the experimental demand stimuli as the dependent variable to investigate demand characteristics as an explanation of the debiasing. The results showed that the debiasing procedure was effective in the reduction of judgmental errors. In addition, it was found that demand characteristics could not account for the reduction in pessimistic threat-related predictions. The results were discussed in terms of cognitive biases and implications for cognitive behavior therapy.