A little learning is a dangerous thing: An experimental demonstration of ignorance-driven inference

Abstract

Studies of ignorance-driven decision making have been employed to analyse when ignorance should prove advantageous on theoretical grounds or else they have been employed to examine whether human behaviour is consistent with an ignorance-driven inference strategy (e.g., the recognition heuristic). In the current study we examine whether—under conditions where such inferences might be expected—the advantages that theoretical analyses predict are evident in human performance data. A single experiment shows that, when asked to make relative wealth judgements, participants reliably use recognition as a basis for their judgements. Their wealth judgements under these conditions are reliably more accurate when some of the target names are unknown than when participants recognize all of the names (a “less-is-more effect”). These results are consistent across a number of variations: the number of options given to participants and the nature of the wealth judgement. A basic model of recognition-based inference predicts these effects.

Acknowledgments

Thanks to Philip T. Smith for useful discussions and to Thorsten Pachur and an anonymous reviewer for comments on an earlier draft of this manuscript. This research was supported by Grant F/00 239/U from the Leverhulme Trust.