Pick a pint glass

Could the shape of your pint glass influence the speed at which you drink your pint?
20 January 2019

Interview with 

Marcus Munafo, University of Bristol




Drinking excessively and smoking cigarettes are major health problems. But can the physical environment around booze and cigarettes impact our behaviour? Katie Haylor spoke with University of Bristol psychologist Marcus Munafo, who's been looking into this. Firstly, Katie wanted to know what goes on in the brain when someone decides to have a 2nd, or maybe 3rd, drink...

Marcus - Well there are a lot of things going on. There are different influences coming from different places. There's the environment that you're in, for example. You're in a social context, you are presented with lots of different cues that might encourage you to have a drink, for example. But then when you have a drink the drug, the alcohol, is having an effect on your brain itself and the disinhibiting effect of alcohol might mean that even if you intended to only have one or two drinks you end up having three, four or five. So you've got this set of competing influences that are acting on different parts of the brain, on the reward centers, on mechanisms that manage to control those impulsive behaviors, and that complicated interplay of effects on different brain regions is difficult to understand, but really important if we want to get a handle on how and why people drink

Katie - Is it a pretty similar picture, if I was to come out of the pub, step outside, and have a cigarette, for instance?

Marcus - Different drugs have different effects. Some of the effects are common to different drugs, some of them are unique to specific drugs. But generally speaking you have this same issue of a range of different influences working in different ways on different parts of the brain, and there are some similarities between different types of drug but there are also some differences as well. So we do need to look at each one individually.

Katie - How are you using neuroscience to understand our behavior around things like smoking and drinking, habits we may want to change?

Marcus - Most neuroscientists tend to start with the brain and understand how the brain works and therefore how that might influence how we use different drugs, for example. Our approach is slightly different, in that we start with cues in the environment that we have reason to believe might be influencing our behavior, and then use human laboratory studies to try and understand how that works. There's been a lot of work done on branding on cigarette packs and how that captures the attention of people who are looking at those cigarette packs. There's also been work done on the design of glasses that you serve beer in and how that might influence drinking behavior. So we're trying to understand what it is about the features of cigarette packs and glasses and so on that influence behavior through those cognitive mechanisms in the brain, to then be able to reverse engineer that knowledge and change people's behavior in a healthier direction by targeting those features.

Katie - Let's hone in on the glasses, then. What is it about different types of drinking glasses that might make us more or less likely to drink?

Marcus - Well, if you go into a bar now you'll see that certainly if you order a pint of lager there'll be an array of different glasses that that drink will be served in depending on exactly what drink you order.

Katie - Sure. So, you've got your standard pint glass which actually isn't straight, is it? It kind of comes out a little bit at the top. You've got the really fancy Belgian beer glasses, a whole array.

Marcus - That's right. So they're shaped so that most glasses are curved. They will often, certainly if they're being used to serve lager, will have a nuclear nation stamp on the inside, which is texture on the inside of the glass that promotes bubble formation that keeps it fizzy, that keeps the head on your lager, and so on. There's branding typically on the glass, so depending on which brand of beer you're drinking you'll be served that beer in that specific glass, and all of those things have been introduced for a reason, or might have been introduced for a reason. So, understanding what impact they have on how fast you drink, or whether or not you'd like the taste of the drink, is important if we want to then be able to decide which of those features we might want to modify to promote healthier behavior.

Katie - And is there evidence to suggest that those kinds of aspects of the glass really do make a difference on someone's drinking behavior?

Marcus - Well, there is some evidence. It's still quite early days, but we ran one laboratory study where we brought people in and we randomised them to drink from either a curved glass or a straight glass. One of the things that we did was look at how people judge the halfway point on different shaped glasses using psycho-physical techniques. If you've ever had a hearing test, you have taken part in that kind of study where you have a staircase procedure, in the case of a hearing test where you have sounds that are getting louder and then getting quieter, and that going up and going down allows you to detect very precisely the point at which people can and can't hear something, and you can use a similar kind of approach when you ask people to judge where the halfway point is in a glass, for example, by presenting images that have more or less liquid in them. We found some evidence that when they were drinking lager they tended to drink faster from the curved glass than they did from the straight gl ass. The reason that we think that's happening is because when you look at the glass and try and judge how much is left in it, that's easy to do in a straight glass but much harder to do in a curved glass because the side of the glass is what your eye follows. But actually the volume changes at a different rate to what you might expect from just following the shape on the side of the glass. So in other words when you think you've got to half way in your drink you've actually drunk more like two thirds of it.

Katie - Okay, so if you're saying ‘oh no I'm going to steady myself, I'll have half a pint in half an hour’, actually it's much more difficult than that.

Marcus - Yeah, because by the time you get to where you think it's halfway actually, another couple of drinks and you finished the thing. So, that might have an influence on how fast you drink and we did find some evidence that the greater the extent to which people misjudged how much was left in the glass at the halfway point, the faster they drank. If that's the case, then it suggests ways in which we could reverse engineer that knowledge and shape behavior in a healthier way. We could either put markings on the side of the glass so that people have a clearer cue as to how much of that drink was left. Or we could encourage people to drink from straight glasses because it's easier to make that judgment in a straight glass.

Katie - So that's booze. What about smoking?

Marcus - Well, one of the things that we've been looking at in a series of studies is how branding information, and also health warning information, on packs influences where people look. We used a range of techniques but principally eye tracking. We would have people look at a screen where we presented images of different types of cigarette pack and simply tracked where they were looking and did that for nonsmokers and for smokers. Now this was interesting in the context of the legislation that was introduced a few years ago in the UK, which has required packs to be standardised so that the most prominent feature of cigarette packs now is the health warning and there's very little brand information on them.

Katie - They can be pretty graphic, can't they? Pictures of lungs that look pretty horrible. Well, I would assume, to be fair, as a non-smoker, that they would make a pretty significant impact.

Marcus - Well, there is some evidence from tobacco control research that health warnings do have an impact. Not a huge impact, but as part of a comprehensive tobacco control policy to have a part to play. But we were interested in what happened when you take away the brand information. What we found was that amongst nonsmokers, the presence of a graphic health warning meant that people's attention was captured by that, but amongst smokers they tended to actively look away from the health warning. Even when there was nothing else to look at they would rather look away from the health warning than look at that.

Katie - Wow. So, they actually go into quite a lot of effort to avoid looking at these health warnings.

Marcus - Yeah, it looks like it. It's not necessarily a conscious effort, but they were diverting their attention away from that. So when we looked into that a little bit more deeply and it seems like health warnings are actively pushing the attention of smokers away, and if they're not looking at the health warning then of course there's a limit to the extent to which that health warning can be effective. And that kind of approach can then perhaps give us some insight into how we should design these health warnings, what information we should put on them, how prominent they should be on cigarette packs, and also whether we need to combine that with other approaches like providing a direct piece of information that allows people to take actions. Rather than just saying smoking is bad for you, you could frame the message more positively by saying ‘stopping smoking is good for you, and here's a way of doing that’, with a link to some kind of support website, for example.

Katie - Can these cognitive neuroscience approaches share any insight into resilience? Because it does seem, like in the case of smoking and alcohol, the social environment plays, I would say, probably a massive part, right?

Marcus - Well, I think that's one of the areas where cognitive neuroscience really can tell us something. So, for example, I mentioned earlier the prefrontal cortex is a region that is interesting in the context of drug use, substance use and behavior generally, and that is the region of the brain involved in executive functions, these top down control functions that that inhibit our more impulsive responses, for example. Of course people are different in terms of those functions and therefore different in terms of their ability to inhibit those behaviours, so understanding those mechanisms can give us some insights into why people respond differently, because no two people are the same. Getting a handle on how and why people are different, and how that relates to behaviour, is a big part of this.


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