Seeing is Believing: The Anti-Inference Bias

Abstract

A large body of studies suggests that people are reluctant to impose liability on the basis of circumstantial evidence alone, even when this evidence is more reliable than direct evidence. Current explanations for this pattern of behavior focus on factors such as the tendency of factfinders to assign low subjective probabilities to circumstantial evidence, the statistical nature of such evidence, and the fact that direct evidence can rule out with greater ease any competing factual theory regarding liability.

This article describes a set of four new experiments demonstrating that even when these factors are controlled for, the disinclination to impose liability based on non-direct evidence remains. For instance, people are much more willing to convict a driver of a speeding violation on the basis of a speed camera than on the basis of two cameras documenting the exact time a car passes by them — from which the driver’s speed in the pertinent section of the road is inferred. While these findings do not necessarily refute the existing theories, they indicate that these theories are incomplete and point to the existence of a deep-seated bias against basing liability on inferences — an anti-inference bias. The article dicusses the potential normative implications of the new findings.

Keywords: experimental legal studies, evidence law, circumstantial evidence, simulation heuristic, Wells effect