A neuropsychological test of belief and doubt: damage to ventromedial prefrontal cortex increases credulity for misleading advertising

Authors: Erik Asp , Kenneth Manzel, Bryan Koestner, Catherine A. Cole, Natalie L. Denburg, and Daniel Tranel (University of Iowa)

Publication: Frontiers in Neuroscience

Year: 2012

Focus Area(s): Aging, Decision Making, Consumer Behavior

Relevance: Understanding the neural pathways that underlie belief and doubt offers neuroanatomical insight as to why older adults may be more vulnerable to fraud.

Summary: This article studies brain damaged participants in order to explore the neuroanatomical mechanisms that render individuals susceptible to misleading information. According to the False Tagging Theory (FTT), a theoretical model of belief and doubt, all ideas are initially believed to be true and doubt occurs only when the prefrontal cortex “tags” cognitive representations with false value. The authors of this study suggest that the ventromedial prefrontal cortex (vmPFC) is particularly important for false tagging, such that damage to this area of the brain causes a “doubt deficit” that results in greater credulity.

To test this hypothesis, the researchers showed three groups of participants (18 patients with vmPFC damage, 21 patients with brain damage to other areas of the brain, and 10 participants with no brain damage) several misleading advertisements and tested their belief in the ads, and their intent to purchase the advertised items. The study found that patients with vmPFC damage were much more likely to believe false advertisements and had the highest purchase intention of all three groups.

The  vmPFC tends to disproportionately lose integrity and functionality in old age; thus, the researchers suggest that vulnerability to misleading information and fraud in older adults is likely the result of a damaged “doubt process” mediated by the vmPFC. This finding may enable caregivers and relatives to be more understanding of decision making by older adults.

Author Abstract: We have proposed the False Tagging Theory (FTT) as a neurobiological model of belief and doubt processes. The theory posits that the prefrontal cortex is critical for normative doubt toward properly comprehended ideas or cognitions. Such doubt is important for advantageous decisions, for example in the financial and consumer purchasing realms. Here, using a neuropsychological approach, we put the FTT to an empirical test, hypothesizing that focal damage to the ventromedial prefrontal cortex (vmPFC) would cause a “doubt deficit” that would result in higher credulity and purchase intention for consumer products featured in misleading advertisements. We presented 8 consumer ads to 18 patients with focal brain damage to the vmPFC, 21 patients with focal brain damage outside the prefrontal cortex, and 10 demographically similar healthy comparison participants. Patients with vmPFC damage were (1) more credulous to misleading ads; and (2) showed the highest intention to purchase the products in the misleading advertisements, relative to patients with brain damage outside the prefrontal cortex and healthy comparison participants. The pattern of findings was obtained even for ads in which the misleading bent was “corrected” by a disclaimer. The evidence is consistent with our proposal that damage to the vmPFC disrupts a “false tagging mechanism” which normally produces doubt and skepticism for cognitive representations. We suggest that the disruption increases credulity for misleading information, even when the misleading information is corrected for by a disclaimer. This mechanism could help explain poor financial decision-making when persons with ventromedial prefrontal dysfunction (e.g., caused by neurological injury or aging) are exposed to persuasive information.

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