Washing away our sins
This post was originally published in 2006 on the Alphapsy blog.
A nice paper by Chen-Bo Zhong and Katie Liljenquist in Science about the "Macbeth effect" : a threat to one’s moral purity induces the need to wash. This effect revealed itself through an increased mental accessibility of washing-related concepts, a greater desire for cleansing products, and a greater likelihood of taking antiseptic wipes. Furthermore, they show that physical cleansing alleviates the upsetting consequences of unethical behavior and reduces threats to one’s moral self-image.
They note : "Thus, Lady Macbeth's hope that a little bit of water would clear her of the treacherous murder of King Duncan might not have been a product of literary creativity, but of Shakespeare's acute understanding of the human psyche. If physical and moral purity are so psychologically intertwined, Lady Macbeth's desperate obsession with trying to wash away her bloodied conscience while crying, 'Out, damned spot! Out, I say!' (Macbeth, act 5, scene 1) may not have been entirely in vain."
Actually, the "Macbeth Effect" is an inadequate name, since Lady Macbeth does not alleviate her remorse the slightest bit by washing her hands. We would have coined a "Pilate Effect", which would be more appropriate since by handswashing, Pilate truly gets rid of guilt. (attached illustration shows Pilate by XVIth cent. painter Preti).
This is a beautiful work, but we'd like to see that replicated in different cultures. As it stands now, it can be just another effect of linguistic and cultural habits on people's behavior (not that we are defending this interpretation, but you can't rule it out).
Possible relationships with OCD and religious ritual, as explored by Boyer and Liénart, are tantalizing, but more research is needed, in particular, a replication with OCD- subjects.
Practical applications are substantial : "Given the boost to one's moral self afforded by physical cleansing, how might it influence subsequent behavior? Would adherence to a rigorous hygiene regimen facilitate ethical behavior? Or, would cleansing ironically license unethical behavior? It remains to be seen whether clean hands really do make a pure heart, but our studies indicate that they at least provide a clean conscience after moral trespasses".