Predicting the knowledge-recklessness distinction in the human brain.

Criminal convictions require proof that a prohibited act was performed in a statutorily specified mental state. Different legal consequences, including greater punishments, are mandated for those who act in a state of knowledge, compared with a state of recklessness. Existing research, however, suggests people have trouble classifying defendants as knowing, rather than reckless, even when instructed on the relevant legal criteria. We used a machine-learning technique on brain imaging data to predict, with high accuracy, which mental state our participants were in. This predictive ability depended on both the magnitude of the risks and the amount of information about those risks possessed by the participants. Our results provide neural evidence of a detectable difference in the mental state of knowledge in contrast to recklessness and suggest, as a proof of principle, the possibility of inferring from brain data in which legally relevant category a person belongs. Some potential legal implications of this result are discussed.

Neuroscientific evidence in the courtroom: a review.

The use of neuroscience in the courtroom can be traced back to the early twentieth century. However, the use of neuroscientific evidence in criminal proceedings has increased significantly over the last two decades. This rapid increase has raised questions, among the media as well as the legal and scientific communities, regarding the effects that such evidence could have on legal decision makers. In this article, we first outline the history of neuroscientific evidence in courtrooms and then we provide a review of recent research investigating the effects of neuroscientific evidence on decision-making broadly, and on legal decisions specifically. In the latter case, we review studies that measure the effect of neuroscientific evidence (both imaging and nonimaging) on verdicts, sentencing recommendations, and beliefs of mock jurors and judges presented with a criminal case. Overall, the reviewed studies suggest mitigating effects of neuroscientific evidence on some legal decisions (e.g., the death penalty). Furthermore, factors such as mental disorder diagnoses and perceived dangerousness might moderate the mitigating effect of such evidence. Importantly, neuroscientific evidence that includes images of the brain does not appear to have an especially persuasive effect (compared with other neuroscientific evidence that does not include an image). Future directions for research are discussed, with a specific call for studies that vary defendant characteristics, the nature of the crime, and a juror's perception of the defendant, in order to better understand the roles of moderating factors and cognitive mediators of persuasion.

Neural precursors of decisions that matter-an ERP study of deliberate and arbitrary choice.

The readiness potential (RP)-a key ERP correlate of upcoming action-is known to precede subjects' reports of their decision to move. Some view this as evidence against a causal role for consciousness in human decision-making and thus against free-will. But previous work focused on arbitrary decisions-purposeless, unreasoned, and without consequences. It remains unknown to what degree the RP generalizes to deliberate, more ecological decisions. We directly compared deliberate and arbitrary decision-making during a $1000-donation task to non-profit organizations. While we found the expected RPs for arbitrary decisions, they were strikingly absent for deliberate ones. Our results and drift-diffusion model are congruent with the RP representing accumulation of noisy, random fluctuations that drive arbitrary-but not deliberate-decisions. They further point to different neural mechanisms underlying deliberate and arbitrary decisions, challenging the generalizability of studies that argue for no causal role for consciousness in decision-making to real-life decisions. Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).

Consequences for peers differentially bias computations about risk across development.

Adolescents routinely take risks that impact the well-being of the friends they are with. However, it remains unclear when and how consequences for friends factor into decisions to take risks. Here we used an economic decision-making task to test whether risky choices are guided by the positive and negative consequences they promise for peers. Across a large developmental sample of participants ages 12-25, we show that risky decision computations increasingly assimilate friends' outcomes throughout adolescence into early adulthood in an asymmetric manner that overemphasizes protecting friends from incurring loss. Whereas adults accommodated friend outcomes to a greater degree when the friend was present and witnessing these choices, adolescents did so regardless of whether a friend could witness their decisions, highlighting the fundamentality of adolescent social motivations. By demonstrating that outcomes for another individual can powerfully tune an actor's risk tolerance, these results identify a key factor underlying peer-related motivations for risky behavior, with implications for the law and risk-prevention. (PsycINFO Database Record

What does recent neuroscience tell us about criminal responsibility?

A defendant is criminally responsible for his action only if he is shown to have engaged in a guilty act-actus reus (eg for larceny, voluntarily taking someone else's property without permission)-while possessing a guilty mind-mens rea (eg knowing that he had taken someone else's property without permission, intending not to return it)-and lacking affirmative defenses (eg the insanity defense or self-defense). We therefore first review neuroscientific studies that bear on the nature of voluntary action, and so could, potentially, tell us something of importance about the actus reus of crimes. Then we look at studies of intention, perception of risk, and other mental states that matter to the mens rea of crimes. And, last, we discuss studies of self-control, which might be relevant to some formulations of the insanity defense. As we show, to date, very little is known about the brain that is of significance for understanding criminal responsibility. But there is no reason to think that neuroscience cannot provide evidence that will challenge our understanding of criminal responsibility.

Nonpolitical images evoke neural predictors of political ideology.

Political ideologies summarize dimensions of life that define how a person organizes their public and private behavior, including their attitudes associated with sex, family, education, and personal autonomy. Despite the abstract nature of such sensibilities, fundamental features of political ideology have been found to be deeply connected to basic biological mechanisms that may serve to defend against environmental challenges like contamination and physical threat. These results invite the provocative claim that neural responses to nonpolitical stimuli (like contaminated food or physical threats) should be highly predictive of abstract political opinions (like attitudes toward gun control and abortion). We applied a machine-learning method to fMRI data to test the hypotheses that brain responses to emotionally evocative images predict individual scores on a standard political ideology assay. Disgusting images, especially those related to animal-reminder disgust (e.g., mutilated body), generate neural responses that are highly predictive of political orientation even though these neural predictors do not agree with participants' conscious rating of the stimuli. Images from other affective categories do not support such predictions. Remarkably, brain responses to a single disgusting stimulus were sufficient to make accurate predictions about an individual subject's political ideology. These results provide strong support for the idea that fundamental neural processing differences that emerge under the challenge of emotionally evocative stimuli may serve to structure political beliefs in ways formerly unappreciated.

Neurologic disorder and criminal responsibility.

Sufferers from neurologic and psychiatric disorders are not uncommonly defendants in criminal trials. This chapter surveys a variety of different ways in which neurologic disorder bears on criminal responsibility. It discusses the way in which a neurologic disorder might bear on the questions of whether or not the defendant acted voluntarily; whether or not he or she was in the mental state that is required for guilt for the crime; and whether or not he or she is deserving of an insanity defense. The discussion demonstrates that a just determination of whether a sufferer from a neurologic disorder is diminished in his or her criminal responsibility for harmful conduct requires equal appreciation of the nature of the relevant disorder and its impact on behavior, on the one hand, and of the legal import of facts about the psychologic mechanisms through which behavior is generated, on the other.