Intrinsic motivation and false feedback reduce the low prevalence effect

Previous research has found that people miss a large proportion of targets that appear rarely. This Low Prevalence (LP) Effect has implications for applied tasks such as mammography. The current study investigated whether the LP effect can be reduced by feedback and internal incentives, which affect motivation. Experiment 1 found that miss errors were reduced when participants were given false feedback about missed cancers; however, this also led to increased false alarm rates. Experiment 2 found no reduction in miss errors and an increase in false alarms when participants were given false feedback about both miss error and false alarm rates. Experiments 3 and 4 investigated the effect of signing a pledge on LP search. In Experiment 3, participants searched through a meaningless letter visual search task, whereas in Experiment 4 participants searched for a cancer in a mammogram. The results found that signing a pledge reduced the LP effect in the letter search task but not in the mammogram task. Experiment 5 found that the LP effect was reduced in the mammogram search task when the medical importance was emphasised to participants. Overall, the results demonstrate the importance of motivational factors in LP search.