How we eat says a lot about us. How we say we eat also says a lot about us. Rachel Herz is a psychologist and neuroscientist who teaches at Brown University and Boston College. She has written a book called Why You eat What You Eat: The Science Behind Our Relationship with Food, a fascinating read about the psychology of our food choices. And a lot of what she's found is probably not what most people would expect.

Francis Lam: Can you tell us about the study regarding people who brought their own bags while shopping at the grocery store?

Rachel Herz:  People who bring their own bags to the grocery store do it out of their own free will. It's different if you shop in places where they penalize you for not bringing your own bags – and plastic costs money – or they don't have it, or whatever the case might be. But if you're still somewhere in the country where you're doing something virtuous by bringing your own bag and being conscientious about the environment, then two things tend to happen: one is that you buy more organic produce and products, which isn't all that surprising considering that if you're being environmentally conscientious you're probably also concerned with eating organic food.

The part that is surprising, however, is that people who bring their own bags often tend to put more treats into the carts for themselves than people who don't. And this is because we have this incredible balancing act within ourselves of matching our virtues with our vices. So, bringing that reusable bag – which is good for Mother Nature – makes you feel like you deserve a little pat on the back, and in a grocery store that comes in the form of something tasty that you like to eat. Now this happens only when people are shopping for themselves. If you're shopping for the family, you're less inclined to put extra treats in your cart. But if you're a singleton shopping with your reusable bag, you end up buying yourself more goodies – which is not necessarily virtuous from the point of view of responsible eating. But I think we all deserve a little treat now and then, and it's a good reason to give yourself one if you're doing something good for Mother Nature.

Another study that had to do with grocery shopping had radio frequency tags on the grocery carts themselves and focused on the geography of the grocery store. After people had shopped in the produce section and put the kale into their basket, the next area of the store they went to was either the alcohol or the ice cream departments. Again, balancing good with bad.

Rachel Herz Photo: Kathleen McCann

FL: You know, that's amazing. Really? So people just naturally think, hey, I bought kale – now I'm going to go get some booze. Like that's the next thing you shop for?

RH: Obviously this is on a semi-unconscious level. Most people I know set themselves up for little goals. For instance, if I stay at my desk working on this grant – or whatever it is I'm working on – for another hour, I'll let myself have a cookie. Or maybe I’ll go to the gym today, but then I'm going to drink beer tonight. The problem is that often these things, in caloric terms, don't balance themselves out. And people really have an expectation when it comes to exercise: we burn more calories exercising than sitting still. But the amount of calories we burn for various activities depends on static height and weight to start with, and it is not as much as we think. Often, we're making up with it for a handful of extra cookies or muffins, which have tremendous amount of calories.

FL: You have another story in the book that I'm fascinated by. It's an anecdote – this wasn't a study, I don't think. You mentioned a person who said to you that when she leaves a Whole Foods and sees a Salvation Army volunteer asking for donations, she feels annoyed by that person. But when she leaves a Walmart and sees that person, she is happy to give to them. Tell me about how that matches in your virtue and vice balancing thing.

RH:  That's an anecdote which explains other research that has found when people shop in an environment highly promoting of organic products with a lot of labeling, it has this sort of imbued moral superiority. The branding actually makes people feel that they are morally superior, that after they have done the morally superior thing of purchasing said products, they are [morally superior]. But in fact, they are less kind to other people, less generous, and more likely to engage in immoral acts like being deceitful, lying, and stealing. Not robbing a bank or anything like that, but –

irvin lin (photo: alec joseph bates) Why You Eat What You Eat by Rachel Herz

FL: Being a jerk.

RH: Being a jerk, but also even more immoral than that. One study looked at people who were shopping in virtual marketplaces. One was a conventional virtual store and the other was an organic-end type of virtual store. After people had been online shopping in the organic virtual store and later played an online game where there was opportunity for stealing or lying to your opponent, they were much more likely to behave with deceitful behavior than the people who'd been shopping in the conventional store where there were matched products like Pringles versus organic potato chips or something like Back to Nature. The point is, this language makes us feel morally superior, and when we are morally superior – or we think we are morally superior – we tend to behave badly.

This is based on other research in morality. For instance, if you give somebody an antiseptic wipe after they have reported something that they did in their past, like admit to a time that they were lying – and then you give them an antiseptic wipe – they are much more likely to then do something else immoral than if they told their little past transgression and didn't clean their hands in the Lady Macbeth kind of way.

FL: Oh my goodness. That's so wild. Like that metaphor really means something to us psychologically, like we're actually clean now, so we're going to do something gnarly again.

RH: Exactly. It is fascinating. The idea behind these simple acts is called embodied cognition – we do something physical and it actually affects our state of mind. We do something like cleaning our hands and we feel morally cleansed and therefore capable of engaging in transgressions again because we've cleaned the slate – and, in fact, may be starting at an even higher point than having done nothing in the past. Similarly, when we're grocery shopping and we purchase products that describe themselves as morally superior by the branding, we often behave in negative ways. Other research on the same topic found that when people saw labels like USDA Organic on products they were more likely to be harsher in their evaluations on other people and moral transgressions and so forth. So, it makes us more judgmental of others as well. In the case regarding the anecdote of grocery shopping – after being in an environment where there's all this moral purity being expounded upon in your groceries – people are less inclined to be generous, as opposed to in an environment where moral purity isn't as sanctified and blared from every speaker.

Francis Lam
Francis Lam is the host of The Splendid Table. He is the former Eat columnist for The New York Times Magazine and is Vice President and Editor-in-Chief at Clarkson Potter. He graduated first in his class at the Culinary Institute of America and has written for numerous publications. Lam lives with his family in New York City.