ORIGINAL RESEARCH ARTICLE published: 09 July 2012 doi: 10.3389/fnins.2012.00100 A neuropsychological test of belief and doubt: damage to ventromedial prefrontal cortex increases credulity for misleading advertising Erik Asp1†, Kenneth Manzel 1†, Bryan Koestner 1, Catherine A. Cole 2, Natalie L. Denburg 1 and Daniel Tranel 1,3* 1 Division of Behavioral Neurology and Cognitive Neuroscience, Department of Neurology, University of Iowa College of Medicine, Iowa City, IA, USA 2 Department of Marketing, University of Iowa, Iowa City, IA, USA 3 Department of Psychology, University of Iowa, Iowa City, IA, USA Edited by: Gregory R. Samanez-Larkin, Vanderbilt University, USA Reviewed by: Vinod Venkatraman, Duke University, USA Ami Tsuchida, McGill University, Canada *Correspondence: Daniel Tranel, Department of Neurology, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, 2155 RCP, Iowa City, IA 52242, USA. e-mail: daniel-tranel@uiowa.edu †Erik Asp and Kenneth Manzel have contributed equally to this work. 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 advanta- geous 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 cor- tex, and 10 demographically similar healthy comparison participants. Patients with vmPFC damage were (1) more credulous to misleading ads; and (2) showed the highest inten- tion to purchase the products in the misleading advertisements, relative to patients with brain damage outside the prefrontal cortex and healthy comparison participants. The pat- tern 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 mislead- ing information, even when the misleading information is corrected for by a disclaimer. This mechanism could help explain poor ﬁnancial decision-making when persons with ventro- medial prefrontal dysfunction (e.g., caused by neurological injury or aging) are exposed to persuasive information. Keywords: prefrontal cortex, deception, advertising, lesion, credulity, false tagging theory, belief, doubt INTRODUCTION It may seem like a stroke of good luck to be contacted by a Nigerian prince who is in trouble. The individual often claims to have some connection to a large fortune but needs a foreign investor’s help to access it. Victims of this fraud scheme may send thousands of dollars to this individual with the promise of a 10- fold payoff in return. Unfortunately for victims, the reward never arrives. Fraud, an intentional deception made for personal gain, is a crime and has reached epidemic levels in older adults. An esti- mated 7.3 million adults 65 years of age or older (20% of older Americans) have been the victims of ﬁnancial fraud according to a 2010 survey (Infogroup/ORC, 2010). Research has suggested older adults are disproportionally vulnerable to fraud and decep- tion in general (Gaeth and Heath, 1987; Chen and Blanchard- Fields, 2000; Chen, 2002, 2007). However, we remain without an adequate understanding of the elderly individual’s propensity toward credulity when exposed to persuasive messages. More- over, we still do not understand the neuroanatomical mechanisms which (1) are critical in belief and doubt processes, and (2) might show disproportional dysfunction in connection with age-related increases in credulity. A central goal of our research is to investigate the underlying neuroanatomical mechanisms which are engaged when one becomes dubious or skeptical. The studies highlighted above have indicated that older adults may have impairments in these mechanisms but do not address from a neuroanatomical perspective why older adults are more vulnerable to deception and misleading information, which often results in poor ﬁnancial decision-making. Denburg et al. (2007) have indicated that the vulnerability to misleading information in older adults may be linked to an impair- ment in prefrontal cortex functioning. The structural integrity of the prefrontal cortex is preferentially diminished relative to other brain regions in some older adults (Dempster, 1992; Raz et al., 1997; Pfefferbaum et al., 2005); and there is a decline in frontal lobe functioning beyond the sixth decade of life (West, 1996; Phillips et al., 2002). However, this leaves us with the question of how pre- frontal cortex dysfunction results in vulnerability to misleading www.frontiersin.org July 2012 | Volume 6 | Article 100 | 1