Toward A Neuroscientifically Informed “Reasonable Person” Test

Abstract

Legal tests invoking the viewpoint of a so-called reasonable person play an important role in many domains of the law, ranging from intellectual property to free speech. In such cases, a central question involves determining how a hypothetical individual with “an ordinary or average level of care, prudence, or knowledge” would respond. Despite the seemingly commonsensical nature of these tests, their judicial application can be controversial due to concerns about subjectivity and vulnerability to explicit or implicit biases. Here we take a step toward addressing these concerns by using neuroscientific tools to observe, without the use of self-report, the nature of mental representations central to a set of disputes invoking the reasonable person. Specifically, using an fMRI-based measure, repetition suppression, to generate a neural index of subjective visual similarity, we sought to inform the application of the reasonable person test to a class of intellectual property law that evaluates whether a trademark is so similar to another as to generate consumer confusion. We show that, by leveraging well-established neuroscientific knowledge about visual processing, it is possible to construct a parsimonious neural index of subjective similarity using signals from object-sensitive brain regions identified a priori. Moreover, this neural index, aggregated across multiple participants, is sufficiently precise to detect instances of experimenter-induced bias in behavioral reports. Together these findings shed light on the potential evidentiary value of neuroscientific data to inform questions involving the reasonable person and suggest a novel domain for the use of neuroscience in law.