N. J. Schweitzer

Fooled by the brain: Re-examining the influence of neuroimages

A series of highly-cited experiments published in 2008 demonstrated a biasing effect of neuroimages on lay perceptions of scientific research. More recent work, however, has questioned this bias, particularly within legal contexts in which neuroscientific evidence is proffered by one of the parties. The present research moves away from the legal framework and describes five experiments that re-examine this effect. Experiments 1 through 4 present conceptual and direct replications of some of the original 2008 experiments, and find no evidence of a neuroimage bias. A fifth experiment is reported that confirms that, when laypeople are allowed multiple points of reference (e.g., when directly comparing neuroimagery to other graphical depictions of neurological data), a neuroimage bias can be observed. Together these results suggest that, under the right conditions, a neuroimage might be able to bias judgments of scientific information, but the scope of this effect may be limited to certain contexts.

Visual Attention and the Neuroimage Bias

Several highly-cited experiments have presented evidence suggesting that neuroimages may unduly bias laypeople’s judgments of scientific research. This finding has been especially worrisome to the legal community in which neuroimage techniques may be used to produce evidence of a person’s mental state. However, a more recent body of work that has looked directly at the independent impact of neuroimages on layperson decision-making (both in legal and more general arenas), and has failed to find evidence of bias. To help resolve these conflicting findings, this research uses eye tracking technology to provide a measure of attention to different visual representations of neuroscientific data. Finding an effect of neuroimages on the distribution of attention would provide a potential mechanism for the influence of neuroimages on higher-level decisions. In the present experiment, a sample of laypeople viewed a vignette that briefly described a court case in which the defendant’s actions might have been explained by a neurological defect. Accompanying these vignettes was either an MRI image of the defendant’s brain, or a bar graph depicting levels of brain activity–two competing visualizations that have been the focus of much of the previous research on the neuroimage bias. We found that, while laypeople differentially attended to neuroimagery relative to the bar graph, this did not translate into differential judgments in a way that would support the idea of a neuroimage bias.

Making sense of research on the neuroimage bias

Both academic and legal communities have cautioned that laypersons may be unduly persuaded by images of the brain and may fail to interpret them appropriately. While early studies confirmed this concern, a second wave of research was repeatedly unable to find evidence of such a bias. The newest wave of studies paints a more nuanced picture in which, under certain circumstances, a neuroimage bias reemerges. To help make sense of this discordant body of research, we highlight the contextual significance of understanding how laypersons’ decision making is or is not impacted by neuroimages, provide an overview of findings from all sides of the neuroimage bias question, and discuss what these findings mean to public use and understanding of neuroimages.