Do lies make your mouth dirty?
No, but it can feel like they do. The connection between metaphorical and physical dirtiness goes much deeper than you might think.
Research subjects who lied with their voice subsequently preferred mouthwash when picking among consumer products. People who lied via email (with their hands) preferred hand sanitizer.
They were also willing to pay more for the product that cleansed the “dirty” part of their body.
Lee and Schwarz (2010a) had participants complete a role-playing task in which they conveyed a malevolent lie by voicemail (using their mouth) or email (using their hands). Then participants evaluated several consumer products, including mouthwash and hand-sanitizer. As expected, participants who had to lie with their mouth preferred mouthwash over hand-sanitizer, whereas those who had to type the same lie with their hands preferred hand-sanitizer over mouthwash. Participants were also willing to pay more for the product that cleansed their “dirty” body part (Figure 1).
Source: “Wiping the Slate Clean: Psychological Consequences of Physical Cleansing” from Current Directions in Psychological Science
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