Asp et al. Neural correlates of credulity were not signiﬁcantly different in the way they were affected by the presence of corrective information, F (2,44) D 1.02, p D 0.37. Thus, the corrective information did help the vmPFC patients increase their skepticism similarly to the comparison groups. PURCHASE INTENTION DIMENSION For the purchase intention dimension, we addressed ﬁrst whether vmPFC patients overall were more likely to have intent to purchase the advertised products. VMPFC patients had higher purchase intention for the misleadingly advertised products (M D 4.17, SD D 0.64) than BDC patients (M D 4.40, SD D 0.43) and normal participants (M D 4.70, SD D 0.27; Figure 4). Again, we used age and sex as covariates in an ANCOVA analysis. The covariate, age, was not signiﬁcantly related to purchase intention, F (1,44) D 0.93, p D 0.34; and the covariate, sex, was also not signiﬁcantly related to purchase intention, F (1,44) D 2.17, p D 0.15. There remained a signiﬁcant difference in purchase intention after controlling for the covariates, F (2,44) D 3.75, p D 0.03. Planned contrasts revealed that vmPFC patients had signiﬁcantly higher purchase intention than normal participants, t (44) D 2.74, p D 0.005; vmPFC patients FIGURE 4 | Mean purchase intention scores for misleading ads. The scale is from 1 to 5 (y -axis). Lower values reﬂect increased purchase intention for the products misleadingly advertised, and higher values reﬂect decreased purchase intention. Error bars indicate SEM. The graph on the left of the black bar represents results for all six misleading ads; the graph on the right of the black bar breaks the results down according to “deception-uncorrected” and “deception-corrected” ads. For all the ads, vmPFC patients had higher purchase intention than BDC patients and normal comparison participants for the products in the misleading ads. did not have signiﬁcantly higher purchase intention than the BDC patients, t (44) D 1.13, p D 0.13. Lesion size was uncorrelated with purchase intention, r D 0.04, p D 0.81. When the purchase intention data were divided into “deception-uncorrected” and “deception-corrected,” the results indicated that vmPFC patients had higher purchase intent for the “deception-uncorrected” ads (M D 4.35, SD D 0.70) than BDC patients (M D 4.52, SD D 0.39) and normal participants (M D 4.90, SD D 0.16; Figure 4). There was a signiﬁcant difference for group purchase intention on the “deception-uncorrected” ads, F (2,46) D 3.86, p D 0.03. Planned contrasts showed that vmPFC patients had higher purchase intention than normal participants, t (20) D 3.18, p D 0.003; but did not signiﬁcantly differ from BDC patients, t (26) D 0.93, p D 0.18. VMPFC patients also had higher purchase intent to the “deception-corrected” ads (M D 4.00, SD D 0.67) than BDC patients (M D 4.27, SD D 0.72) and normal participants (M D 4.50, SD D 0.45; Figure 3). However, group dif- ferences on “deception-corrected” ads for purchase intention did not reach signiﬁcance, F (2,46) D 1.99, p D 0.14. Planned contrasts revealed that vmPFC patients had signiﬁcantly higher purchase intention than normal participants, t (46) D 1.94, p D 0.03; but did not signiﬁcantly differ from BDC patients, t (46) D 1.28, p D 0.11. DISCUSSION Our ﬁndings support the hypothesis that credulity toward mis- leading information can result from damage to the vmPFC. Patients with vmPFC damage tended to (1) believe misleading advertisements, and (2) show higher intent to purchase the prod- ucts featured in the misleading advertisements, relative to patients with brain damage outside of the prefrontal cortex and normal comparison participants. Remarkably, the pattern of credulity results was evident even when vmPFC patients were given speciﬁc information that rebuts the misleading claim. This suggests that the deﬁciency in vmPFC patients is speciﬁc to the doubt process, not a lack of knowledge regarding misleading information. Thus, the results indicate that given a deceptive ad (with or without a dis- claimer) vmPFC patients are more credulous. The disclaimer did increase skepticism in vmPFC patients (similarly to the compari- son groups) but overall the disclaimer did not produce normative skeptical levels in vmPFC patients. Thus, there is a deﬁciency in skepticism generally, even when speciﬁc rebutting knowledge cues a doubting process. The conclusion that damage to the vmPFC causes an increase in credulity to misleading information is bolstered by the facts that (1) brain damage, per se, when outside of the prefrontal cortex, does not account for the results (as evident from the BDC data); (2) demographic variables such as age, education, or sex, per se, do not account for the results; and (3) general cognitive functioning, such as intelligence, memory, reading performance, or executive functioning, per se, does not account for the results. Instead, the vmPFC patients’ deﬁcit in skepticism to the misleading informa- tion is speciﬁc to their lesion location and is not accounted for by generally poor cognitive functioning. The vmPFC patients did have larger lesions relative to the BDC patients (Table 1). However, it is unlikely that lesion size, per se, inﬂuenced the credulity or purchase intention results. A detailed www.frontiersin.org July 2012 | Volume 6 | Article 100 | 7