Does It Matter Whether You or Your Brain Did It? An Empirical Investigation of the Influence of the Double Subject Fallacy on Moral Responsibility Judgments.

Uri Maoz,Jeroen J A Van Boxtel,Kellienne R Sita,Liad Mudrik

doi:10.3389/fpsyg.2019.00950

Abstract

Despite progress in cognitive neuroscience, we are still far from understanding the relations between the brain and the conscious self. We previously suggested that some neuroscientific texts that attempt to clarify these relations may in fact make them more difficult to understand. Such texts—ranging from popular science to high-impact scientific publications—position the brain and the conscious self as two independent, interacting subjects, capable of possessing opposite psychological states. We termed such writing ‘Double Subject Fallacy’ (DSF). We further suggested that such DSF language, besides being conceptually confusing and reflecting dualistic intuitions, might affect people’s conceptions of moral responsibility, lessening the perception of guilt over actions. Here, we empirically investigated this proposition with a series of three experiments (pilot and two preregistered replications). Subjects were presented with moral scenarios where the defendant was either (1) clearly guilty, (2) ambiguous, or (3) clearly innocent while the accompanying neuroscientific evidence about the defendant was presented using DSF or non-DSF language. Subjects were instructed to rate the defendant’s guilt in all experiments. Subjects rated the defendant in the clearly guilty scenario as guiltier than in the two other scenarios and the defendant in the ambiguously described scenario as guiltier than in the innocent scenario, as expected. In Experiment 1 (N = 609), an effect was further found for DSF language in the expected direction: subjects rated the defendant less guilty when the neuroscientific evidence was described using DSF language, across all levels of culpability. However, this effect did not replicate in Experiment 2 (N = 1794), which focused on different moral scenario, nor in Experiment 3 (N = 1810), which was an exact replication of Experiment 1. Bayesian analyses yielded strong evidence against the existence of an effect of DSF language on the perception of guilt. Our results thus challenge the claim that DSF language affects subjects’ moral judgments. They further demonstrate the importance of good scientific practice, including preregistration and—most critically—replication, to avoid reaching erroneous conclusions based on false-positive results.

Highlights

The neuroscientific study of voluntary action sparked an ongoing debate, both inside and outside of academia, about the intricate relations between the conscious self and the brain
Experiment 1 provided first evidence for a possible effect of Double Subject Fallacy” (DSF) language on the way people perceive moral responsibility: subjects who were presented with neuroscientific evidence described in DSF language were more lenient in assigning defendant guilt
This implies that DSF language might affect judgments of moral responsibility, making people assign less responsibility to others if “their brain made them do it” (Mudrik and Maoz, 2014)

Summary

Introduction

The neuroscientific study of voluntary action sparked an ongoing debate, both inside and outside of academia, about the intricate relations between the conscious self and the brain. In popular science books and debates, which commonly lay the foundation on which lay perceptions of neuroscience are formed, the brain is often described as separate from the self, and—critically—as capable of interacting with the self while possessing opposing psychological states to those held by the self (Damasio, 1994; LeDoux, 2003; Gazzaniga, 2006; Frith, 2007; Rizzolatti and Sinigaglia, 2008). Such writing is not limited to popular science. Quite strikingly, be found in scientific papers published in leading journals (Libet et al, 1983; Keysers and Perrett, 2002; Pearson and Clifford, 2005; Cerf et al, 2010; Simon and Gogotsi, 2010). (For a full discussion, see Mudrik and Maoz, 2014.) Echoes of this type of writing can be found in the increasing use of neuroscientific evidence in courtrooms (Garland and Glimcher, 2006; Chandler, 2016; Meixner, 2016), typically as part of the “my brain made me do it” defense (Morse, 2004; Gazzaniga, 2006; Sternberg, 2010; Maoz and Yaffe, 2015)

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