CANCER SCREENING DECISIONS: THE IMPACT OF THE AFFECT HEURISTIC IN INTERPRETATION OF TEST RISKS AND BENEFITS

Purpose: Recently, expert panels have advised many Americans to reduce the frequency of screening tests for various cancers (e.g. prostate, breast).  However, these recommendations are often met with considerable resistance from the general public.  One possible way to explain this resistance is that when people feel positively toward a given behavior, they assume that the benefits of that behavior are high and the risks are low—a phenomenon known as the affect heuristic. The purpose of the present research was to determine whether the affect heuristic results in systematic biases in interpretations of screening test information. 

Method: 311 participants were recruited online and read information about the risks and benefits of a screening test (e.g. this test may detect disease before it becomes dangerous, this test may lead to unnecessary further testing and treatments that are expensive and painful).  This risk and benefit information was identical for all participants, but the screening test label was experimentally varied; participants were told that the test was for an unspecified disease, an unspecified cancer, or colon cancer.  Outcome measures included perceptions of risks and benefits of the test, and decisions to get screened or not. 

Result: Participants who believed that the test was for colon cancer were significantly more likely to decided to get the test (57%) than participants who believed the test was for an unspecified disease (38%) or unspecified cancer (41%), χ²(1)=4.67, p=.03  They also perceived the benefits as higher (M=6.38) than participants in the unspecified disease and cancer conditions (Ms=5.01 and 5.36; F(2,293)=10.39, p<.001), and the risks as lower (Ms=5.14 vs. 6.11 and 6.10; F(2,293)=6.94, p=.001). When controlling for perceptions of risks and benefits, there was no longer a relationship between test label and screening decisions (p=.61). 

Conclusion: Participants were more likely to get screened for colon cancer than an unspecified cancer or disease, even though the test information was identical for all participants.  As predicted by the affect heuristic, participants considering a colon cancer test underweighted the risks and overweighed the benefits of the test, compared to participants who judged the same information with different labels. These results demonstrate that interpretations of screening test information may be systematically biased, and can help to explain the difficulty of communicating screening test recommendations to the public.