Following on my post last spring about mood hacking, October brought more hints that behavior can be explicitly modified using scents.  A variety of news outlets picked up on a press release from BYU describing a forthcoming paper in Psychological Science that demonstrates, "that clean scents not only motivate clean behavior, but also promote virtuous behavior by increasing the tendency to reciprocate trust and to offer charitable help."  Here I am quoting from a pre-print, entitled "The Smell of Virtue", cached at the University of Toronto.  The paper describes two experiments in which citrus-scented window cleaner appeared to alter behavior.  I have to say that I found the references to Proust, saints, sinners god, and cleanliness (all that in 4 pages!) to be distractions from the main ideas, not to mention the data.

Here is the ScienceDaily reporting, and here is Time's take.

(Not everyone is happy with the methodology described in the paper, the conclusions, and the way it was written.)

What makes this interesting (to me) is that the researchers don't necessarily imply a direct biological mechanism.  The induced behavior may simply be the result of a learned association.  That is, there is no suggestion that anything about the scent that serves to flip a biological switch that leads to different behavior.  Rather the lead author, Katie Liljenquist of BYU, and her colleagues had  previously demonstrated a link between transgression and a desire for cleanliness (see "Washing Away Your Sins: Threatened Morality and Physical Cleansing", Science, 313(5792), 2006).  "Out, damned spots!" and all that.

The citrus scent may simply something that Prof. Liljenquist's test subjects (probably undergraduates at US universities) have learned to associate with cleanliness.  Would students at Asian universities have the same response to the same scent?  I suppose one way to quickly address this question is to see what sort of scents Asians prefer in their window cleaners.  Here is my point: even though there may be no innate molecular pathway exploited in this "behavior reprogramming", it may still be possible to exploit culturally defined (or perhaps "contextually constructed") neural pathways (from the receptors to the brain) for the purpose of mood hacking.

I am not particularly excited about the possibility of having my own mood hacked without my knowledge.  That this might be accomplished even in the absence of genetically identifiable response pathway should give one pause.  Any molecular pathway responsible for this effect (should it prove reproducible and engineerable) is unlikely to be well understood for many years to come.  But if the results from the citrus-scent study are to be believed, then it is already possible to manipulate behavior using scents, even though we have little idea how to defend against it other than by using more scents.  Perfume warfare.  Lovely.

Can't wait until the iGEM undergraduates get a hold of this.  They have already built bugs that smell like bananas and mint.  When will they start trying to influence the judges' decisions directly using synthetic scent pathways?