The Spillover Effect in Behaviour Change

For example, if a person starts recycling at home, they may also become more environmentally conscious and make more sustainable choices in other areas of their life, such as using public transportation instead of driving or buying locally-sourced products. This is known as a positive spillover effect.

Speaking with Dr Sarah Kneebone, Geoff Paine explores this phenomenon and discusses Sarah's research looking into over 150 water saving behaviours in households. After conducting an impact-likelihood matrix on all of these behaviours, Sarah highlights interesting findings on 'similar' behaviours - what do we mean by 'similar' behaviours and does that impact behavioural spillover?

Watch the full episode of Pocket Change, The Spillover Effect:

Interested in learning more about the spillover effect? Read our blog on 'What is the Spillover Effect and can it be used to promote pro-environmental behaviours'.

The Spillover Effect blog

Pocket Change is a series of pocket-size videos about a key aspect of behaviour change.  Each episode features a BehaviourWorks Australia Researcher explaining their area of expertise in a clear and simple manner.  

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Transcript:

Geoff

Hi, Geoff Paine here and I'm talking to Sarah Kneebone this time. Tell us about spillover, what does it mean?

Sarah

So spillover, the spillover effect, is the idea that participating in one behaviour increases the chances that you will adopt another additional behaviour.

Geoff

So when we talk about spillover in water saving behaviours, it's got nothing to do with the spillover effect of liquid. It's spilling over behaviour.

Sarah

It's nothing to do with the spilling of liquid, it's about when you perform one behaviour; the theory is that performing one behaviour will create changes in your self, which then increases the likelihood that you will adopt another similar behaviour.

Geoff

So what's an example of a water saving behaviour that may have a spillover effect?

Sarah

So, for example, if you were to install a water tank outside in your garden to collect rainwater, you might be more likely to also install an irrigation system. So we looked at water saving behaviours in a domestic sense, and found some 151 different behaviours just in the home. In and around the home.

Geoff

Right. Okay. And you had of course, I think you developed a matrix in terms of impact?

Sarah

Yeah, that's right. So we were really interested in, given that so many different behaviours that you could perform that would help save water around the home, what does that mean for the household? If we want to inform the household and support the household or to select a behaviour that is going to have the greatest impact, which ones should we pick?

Geoff

Right.

Sarah

And so we developed a tool that was about prioritisation. So out of all those 151 behaviours, we're not going to give that to the householders because that's a long shopping list. And what tends to happen when you're given a long shopping list of behaviours is that you pick the easiest one.

Geoff

Sure.

Sarah

And unfortunately for us, the easiest behaviour is not necessarily the one that is going to have the greatest impact on the issue.

Geoff

Stuff that is simple to do that people find easy to do is not necessarily the most impactful behaviour in terms of water saving.

Sarah

That's exactly it. So things we were interested in, not just looking at about the ease of the behaviour to perform and ease comprises a number of different elements as a physical, physical ease, the financial cost, the the intellectual effort.

So how much planning, how much thought process has to go into it? But we were also interested in the impact on the issue, right? So we actually ended up with two different datasets. We talked to householders to talk about how they saw their perceptions of ease. How would these behaviours, in terms of their physical, financial cost
and so on and so forth.

But then we've got another data set from water experts from across Australia, and they were asked to assess these behaviours in terms of the impact on the issue, in terms of the impact on water saving. So we ended up with two scores. One was about the likelihood of adoption, which was related to ease, and then we also ended up with another score, which was about the impact on issue.

And having those two scores means you could plot every single behaviour on a graph, right? And then you can overlay the graph with a framework which then gives you some idea about which of those behaviours might be most appropriate for you to select which of those behaviours are going to be a priority.

But in terms of spillover, what's really interesting is that the theory suggests that creating those changes within yourself from performing the behaviour. So it's about, for example, learning. So if you do one behaviour that gives you some knowledge and skills, which means you're more able to do another behaviour, there's also self-efficacy. This is related to learning, but this is about your own belief that you can perform the behaviour well. There's also sort of our internal desire for consistency. This feeling that's also known as dissonance. So this is if we perform,
if we do something that is in contradiction to one of our values or one of our beliefs or what we're culturally conditioned to do, that slight feeling of discomfort is motivational. So we prefer to act in ways that is actually consistent with our values, with our beliefs, and with our previous behaviour.

Geoff

So in terms of water saving behaviours in Melbourne, for instance, it is not usual for people to hose down the driveway, let the kids run the sprinklers, run a bath - that is seen as a social taboo. Because of the value of water since the millennial drought.

Sarah

So in performing one water saving behaviour like turning off your tap when you're brushing your teeth, the spillover theory would suggest you're then also more likely to do another water saving behaviour, such as collecting water in the shower. One of the things that my research was was interested in looking at was what did we mean by similar? Because spillover relies on this idea that if you're performing one behaviour, you're more likely to engage in a second behaviour that is similar. Well, what is similar? What do we mean by similar?  Which behaviours are seen as similar
and what criteria do we use to determine similarity?

So if we turn off the tap in the bathroom when we're brushing your teeth, do we also turn off the tap outside when we're watering the plants?  Like those are essentially the same behaviour, but they're occurring in two completely different contexts. So what does this mean? Are they similar or not? So in my work, we assessed those different behaviours that listed different behaviours in terms of how they were seen as similar by householders. So we had people do a sorting exercise where they put behaviours that they saw similar in groups together. And then I coded that and created another graph which showed how similar these different behaviours were to each other and I could cluster them.

So particular behaviours were seen as similar and they occurred in clusters. The second question was why they seem as similar. What is it about the characteristics of those behaviours that made people cluster them? And we encouraged participants to talk about how they had established the groups and what was it about those behaviours that made them similar. And the information from that, the data from that, when I analysed that and looked at which terms were coming through most frequently in relation to these particular clusters, what I found was that people were subconsciously grouping behaviours in terms of location.  

Geoff

Right.

Sarah

So kitchen, bathroom, laundry, outside. So they were using location, the context within which the behaviour was occur. And also the type of behaviour. So was this a habitual behaviour, something that they did all the time? Was it a one-off behaviour like installing a water efficient dishwasher, or was it a maintenance behaviour like checking for leaks, fixing leaks?

Geoff

Okay.

Sarah

So those different, those two main elements, the type of behaviour and the location of the behaviour was really what householders were using to determine whether behaviours were similar to each other or not. So it was interesting to see, but it also meant that those two turning off the tap behaviours, they were quite far apart. And so although it was the same action because they're occurring in different locations, they weren't seen as similar as you would expect.

Geoff

What does this mean?

Sarah

So what this means is that when we are selecting behaviours to prioritise, we can consider things like perception of similarity to existing behaviours. So if we know our target audience is already engaging in a particular activity or performing a particular behaviour, we can promote to them something else which is similar. So if we know that people are already turning off the tap to brush their teeth, if we promote the idea of collecting water in the shower, then more likely, if the spillover theory is correct. They're more likely to engage in that saving water in the shower activity because it is also a habitual behaviour and it's also located in the bathroom.

The spillover theory is still being investigated because it holds a huge amount of potential, right? If we can encourage people to do an easy but low impact behaviour to start them off, we can start them off on what has been dubbed the virtuous escalator. So they start off with something very simple, you know, turning off the light switch, turning off the tap, and we step by step, by step by step, incurring spillover theory, we can get them to hop to more efficacious, more impactful behaviours.  So one at a time.

Geoff

So it starts with a keep cup and it may end up buying an electric vehicle? But there's a lot of steps in between.

Sarah
There's a lot of steps in between. And the and the key, if spillover is correct, is about how can we understand that that similarity because we can't go from turning the tap to the key cup because they're not they have similar outcomes in terms of environmental benefit, but they're not essentially similar to each other. nSo if we can understand similarity on why people see behaviours similar, then that's gives us a lot more information to identify and prioritise particular behaviours to guide people along that route.

I think it's well worth considering those different perceptions. So the perceptions of your target audience, how they view the behaviour, looking at the different characteristics
of the behaviour and considering where the behaviour might lie in terms of a process through which consecutive behaviours could then be promoted. So rather than thinking of an individual behaviour as the endpoint, maybe that's just the start point and we can leverage off spillover, if it is entirely accurate, we can leverage on spillover
to create greater impact over time.

Geoff

Sarah Kneebone, thank you very much.

Sarah

You are welcome.

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