When even the smartest fail to prioritise: overuse of information can decrease decision accuracy

Abstract

Many decisions require prioritising relevant over less relevant information. In risky environments, probabilities provide the weights to use information according to their relevance. We investigated whether participants with high ability and motivation are able to use probabilities effectively for prioritising relevant information and, therefore, decide accurately and achieve better outcomes. A variant of the standard probabilistic inference paradigm of decision research was used for which interindividual variability has been demonstrated. We assessed whether participants’ statistical-methodological competence can explain thesedifferences in decision accuracy. Findings show that even highly capable and motivated participants had difficulty in consistently prioritising relevant information. Participants looked up twice the amount of information necessary. In explicit decision contexts, participants achieved high decision accuracy, yielding high monetary gains. When information was conflicting, the overuse of less relevant information led to a deviation from accurate behaviour and, therefore, inferior decision outcomes. Statistical-methodological competence could not explain the deviation.