A Dissociation Between Two Cognitive Biases in Acute Stress Disorder: Preliminary Evidence for the Reverse Gambling Fallacy

Background: Rationality biases, such as the gambling fallacy (e.g., predicting future coin-tosses based on previous tosses) and the famous “Linda” conjunction fallacy (estimating the conjunction that “Linda” is both teller and feminist based on her description) have not been examined in people suffering from acute stress disorder (ASD). We analyze potential outcomes and align them with different theories. Methods: To discern the precise pattern of rationality biases in persons with ASD, we examined performance on these 2 tasks within a month of the Hayian Super-Typhoon (August 27th, 2013). Out of a sample of 1001 persons, 82 had clinical ASD and their performance was compared to the remaining 919 participants. Results: A specific link between ASD and rationality biases revealed that although conjunction task performance was not associated with ASD diagnosis, coin-task performance was. Namely, responding “Heads” to a 6th coin-toss after 5 successive “Heads” (reverse gambling fallacy) was robustly linked with ASD diagnosis. Conclusion: The results align with the bridging of trauma theories claiming that trauma symptoms are generated by disequilibrium following trauma exposure, with prospect theory’s notion of chance, which is conceived as belief in equilibrium restoration. Such disequilibrium following trauma exposure is thus linked with the belief underlying reverse gambling fallacy biases, namely “what-was-will-be”. Implications regarding themes important to address in therapy are mentioned.