How nudge-theory can’t help supermarkets avoid a backlash over plastic bag bans

​Yesterday a friend of mine – Rafael Batista – got engaged in a Twitter discussion (he often does) about an article at The Conversation titled How ‘nudge theory’ can help shops avoid a backlash over plastic bag bans.
 
We had already discussed why the article conceptually gets nudge-theory quite wrong, but that’s for another day. 

This is all about the power of footprints

​Some years ago my students and I conducted an experiment using stickers of green footprints leading to dustbins to get people not to litter. The experiment as well as the very idea of using footprints to prompt pro-social actions turned out to be quite successful (it has now been replicated in other countries) and popular.
 
Perhaps a bit too popular at times.
 
Thus, in the article the authors write:
 
“Such a strategy [behavioural nudges based on minor adjustments to the environment] could be applied in supermarkets where “footprints” could lead to reusable bags that are available for purchase. Repeating this over time could result in consumers associating the footprints with a reminder to bring their own bags. Varying the location of the footprints, or even their colour or shape, might encourage shoppers’ curiosity and thus increase the likelihood of consciousness about the plastic bag ban.”
 
Now Rafael was not impressed by this passage and asked for my opinion.
 
So, here it is. 

… “footprints” could lead to reusable bags that are available for purchase

​My first thought here is: How?
 
Now footprints are not magical wands that we automatically follow to their destination where after we unconsciously perform some action that they don’t even convey.
 
So why should footprints work in this situation?
 
Is the hypothesis that they should work as an in-store reminder to by re-usable bags instead of bags at the checkout (assuming that this is where they get the bag in the status quo)?
 
If so, this might work for some people, i.e. people who would be willing to pay for re-usable bags instead of getting them for free. Footprints would remind them about the existence of reusable bags before they queue by making that option salient. That is, if they accompanied with semantics telling that they are about buying re-usable bags. How should people otherwise know what they were about and be reminded of what they need to remember?
 
Yet, we should not forget that nudges – especially attention-based nudges such as salient aspects of choice architecture – work in interaction with the underlying choice architecture (which for me is the rational choice structure, not to mistaken with Thaler & Sunstein’s notion of choice architecture which is broader). And the choice architecture, if I read the article correct, has incentives pointing in the direction counter to the nudge: free bags at the counter vs. re-usable bags that costs money.
 
This is not good.
 
However, it seems to me that salience can be used to trigger the Spotlight Effect when applied in public space, whereby existing social norms or status norms may be supported. That was the effect my students’ experiment with the footprints aimed at doing. Yet, this would require that the action (buying re-usable bags rather than choosing the free ones) should be as publicly visible as possible. For instance, reusable bags could be placed mid-aisle before the checkout queue or prompted by staff at the point of purchase.
 
(I also have some much better ideas about how to decrease the use of plastic bags, but those will have to wait until someone steps up and commits to testing them.)
 
But so far so good: footprints could work as part of an intervention, but not as simple as probably not as central as the article portrays.
 
Next.

Repeating this over time could result in consumers associating the footprints with a reminder to bring their own bags

​This assertion is weird to me. An association of the footprints with bringing a bag doesn’t work when the reminder occurs in the store. Or, at least, that would require that people should be willing to go back home to get a bag when they see the footprints in-store.
 
I don’t think that they will be willing to do this. I wouldn’t.
 
However, this assertion strikes me as very similar to the kind of assertions currently promoted heavily by fake “behavioural experts” when talking about behavioural economics and habits (“90% of our behaviour is sub-conscious!”, “A fly in the urinal primes you to eat beef!”, We need to change human habits to get people to save for pensions!”)
 
But as the authors of the article really don’t seem to belong to that category AT ALL, I’m inclined to think that I might be missing something in the idea they put forward – because it just seems a weird suggestion to me.
 
So I think they would have to elaborate on their suggestion in order for us to assess this properly.
 
Next.

Varying the location of the footprints, or even their colour or shape, might encourage shoppers’ curiosity and thus increase the likelihood of consciousness about the plastic bag ban.

,This is also just weird to me – unless you read it as a piece of beautifully formulated satire.
 
First, what is the purpose of “increasing the likelihood of consciousness about the plastic bag ban”?
 
While its sounds clever, why would you? That is, why would we want to put up footprints to ‘increase the likelihood of consciousness” about this in-store?
 
If there’s a ban, people will find out with a likelihood of 1 anyway as soon as they get to the counter… and why are we talking about a ban now? Weren’t the point something about nudges?
 
Still, reading the sentence saved my mood for at least a couple of days. 
 
So what about the first part of the sentence?
 
“Varying the location of the footprints, or even their colour or shape” to encourage shoppers’ curiosity.
 
I think that suggestion is just a bit weird as well. Why would you want people to be curios and what should they be curious about?
 
The plastic bag ban?
 
Why??!!
 
Or, is it still attached to the nudge, i.e. the idea of footprints working as a reminder that you should get some re-usable bags rather than take the free ones at the counter?
 
If so, why would you ever use curiosity as a mechanism here? I don’t get it. What is it supposed to do that mere salience provided by footprints won’t take care of?
 
Perhaps it is because the authors’ think like many others, that salience needs semantic novelty to sustain itself as a reminder.
 
It doesn’t. Rather it usually needs semantic stability to become sustainable.
 
If we varied the sound or even the sensory channel of bells on bicycles (yes, I’m from Denmark, so we have to use that as an example), then I would be dead long ago. A ring today, birds whistle tomorrow, stroboscopic light the day after – my brain would be confused and unable to make any stable association for the salient stimuli to serve as a reminder.
 
I remember when some people suggested this about the footprints and litter bins in Copenhagen. Green today, then blue next month, then yellow… Now that would just ruin top-down salience. People wouldn’t know what to look for when in need of bin.

So, Rafael, I completely agree with you.

I’m not impressed by the passage either. 
 
Of course, I do believe that nudge-theory can help supermarkets reduce plastic bag usage…. And in ways much more elegant and effective than the 5-cents tax that a lot of people have fallen in love with or a ban that may backfire in a new market for re-usable plastic bags.
 
Still, presenting those have to wait until we have tested them.