The Effect of Number Type on Naturalness Perception

Abstract

This research demonstrates a novel effect of number type, sharp versus round, on indvidual’s perception of object’s naturalness. In four online experiments (N = 1,041), we demonstrate that individuals perceive an object to be more natural if its properties are expressed in sharp numbers (vs. round numbers). This is because individuals apply a “natural = sharp number” belief such that sharp numbers are more likely to occur as a random outcome (i.e., being the property of a natural object) than round numbers. However, they erroneously equate the conditional probability of an object’s property being a sharp number provided that it is natural ( p (sharp|natural)) with the conditional probability of an object being natural given that its property is expressed in a sharp number ( p (natural|sharp)). This confusion leads individuals to infer an object’s naturalness from the number type of its property. This inference is stronger for individuals with a stronger “natural = sharp number” belief and decreases for individuals who believe in coincidence thus more accepting of low probability outcomes.

Keywords: round number, naturalness perception, conditional probability, Inverse Fallacy