Overcoming number numbness in prenatal risk communication


OBJECTIVE Efficient prenatal risk communication hinges upon parents' grasp of statistical information. When forming their subjective representation of a probability, pregnant women may focus on inappropriate factors and ignore the appropriate factors. METHOD The present research investigates the subjective probability that pregnant women derive from statements of the form “There is a 1 in X chance that the baby will have condition Y,” where the number X and the severity of the condition Y were orthogonally manipulated. RESULTS Study 1 showed that when judging how big is a 1 in X chance that a child will be affected by condition Y, pregnant women (n = 336) were sensitive to the severity of Y, but selectively numb to the objective number X. Study 2 (n = 461) replicated this pattern, but also showed that numerical numbness could be overcome by a simple intervention, namely, a quick comment that 1 in X was “above average.” CONCLUSION Practitioners must be aware that when forming a subjective probability assessment, pregnant women might be inappropriately sensitive to the severity of Y, and inappropriately numb to the number X, and that a simple communicative intervention can help in overcoming this selective number numbness.

Prenatal Diagnosis
JF Bonnefon
JF Bonnefon
Behavioral Scientist