doi: 10.1098/rstb.2004.1550 , 1749-1754 359 2004 Phil. Trans. R. Soc. Lond. B The Royal Society reasoning and the law A cognitive neuroscience framework for understanding causal Rapid response http://rstb.royalsocietypublishing.org/letters/submit/royptb 359/1451/1749 Respond to this article Email alerting service here right-hand corner of the article or click Receive free email alerts when new articles cite this article - sign up in the box at the top http://rstb.royalsocietypublishing.org/subscriptions go to: Phil. Trans. R. Soc. Lond. B To subscribe to This journal is �� 2004 The Royal Society on June 24, 2010 rstb.royalsocietypublishing.org Downloaded from

Published online 26 November 2004 A cognitive neuroscience framework for understanding causal reasoning and the law Jonathan A. Fugelsang and Kevin N. Dunbar Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH 03755, USA Over the past couple of decades, there have been great developments in the fields of psychology and cogni- tive neuroscience that have allowed the advancement of our understanding of how people make judgements about causality in several domains. We provide a review of some of the contemporary psychological models of causal thinking that are directly relevant to legal reasoning. In addition, we cover some exciting new research using advanced neuroimaging techniques that have helped to uncover the underlying neural sig- natures of complex causal reasoning. Through the use of functional imaging, we provide a first-hand look at how the brain responds to evidence that is either consistent or inconsistent with one���s beliefs and expectations. Based on the data covered in this review, we propose some ideas for how the effectiveness of causal reason- ing, especially as it pertains to legal decision-making, may be facilitated. Keywords: causation causality legal decision-making functional magnetic resonance imaging neuropsychology 1. INTRODUCTION The human mind has evolved many cognitive tools includ- ing abstraction, counterfactual thought, deduction and induction, for a vast variety of circumstances that are applied differently depending on the task at hand. Central to these domain general processes is causal thinking. An individual���s ability to determine if a precipitating event was the cause of an outcome is essential for making sense of the complex world in which we live. Indeed, many of the learn- ing and evaluative processes in which individuals engage pertain to the development and testing of causal models portraying the relationship between variables of interest (Dunbar 1995 Fugelsang et al. 2004). Such causal reason- ing processes are evident in tasks ranging from simple everyday reasoning, such as why one���s computer crashes, to complex scientific discovery, such as the formulation of the ���Universal Law of Gravitation��� in the Principia by The Royal Society���s former president Isaac Newton (Newton 1999). This ability to infer causality is not only crucial for human reasoning in general, but also more specifically to the application of law. The legal system often asks lawyers, jurors and judges to determine if an individual���s actions were responsible for a specific outcome. In so doing, the legal system requires that individuals reason about the evi- dence presented to them in an unbiased manner, formulat- ing a judgement of causality if and only if the evidence presented to them overwhelmingly depict the acts of the defendant as causally responsible for the outcome under question. In the present essay, we address two main questions that are directly relevant to such legal reasoning: (i) what sour- ces of information do people use to evaluate causality, and (ii) to what degree do people evaluate evidence about caus- ality in an unbiased manner? To answer these questions we will discuss both behavioural and fMRI experiments con- ducted in our laboratory and others. 2. LEGAL DECISION-MAKING AND CAUSAL REASONING Whereas much decision-making research in the legal domain has focused on the content-oriented (i.e. substance of the trial itself ) aspects of legal decision-making (e.g. Matlon 1986), research on the extra-legal aspects of legal decision-making (i.e. decision-making strategies of indivi- duals) has primarily been conducted by cognitive and social psychologists (see Pennington & Hastie (1990) for a comprehensive review). Perhaps not surprisingly, much of this work has focused on criminal jury decision-making processes, especially as they pertain to judgements involv- ing more serious crimes often involving capital punishment (e.g. Constanzo & Constanzo 1994 Wiener et al. 1995). The ability of jurors to make decisions in a non-arbitrary and unbiased manner in these situations is of obvious importance. Courts ask jurors to set aside personal beliefs and biases to make judgements in favour of, or against, a defendant based solely on the facts of the case presented to them. This unbiased application of the law is crucial, not only for obvious judicial reasons, but also to maintain con- sistency among rulings within and across jurisdictions. As alluded to in x 1, one���s ability to make such judgements is directly related to one���s ability to effectively attribute caus- ality when presented with evidence. This evidence can come from a variety of sources and often involves the construction of causal chains of events, whereby the link Author for correspondence (jonf@dartmouth.edu). One contribution of 16 to a Theme Issue ���Law and the brain���. Phil. Trans. R. Soc. Lond. B (2004) 359, 1749���1754 1749 # 2004 The Royal Society doi:10.1098/rstb.2004.1550 on June 24, 2010 rstb.royalsocietypublishing.org Downloaded from