Why a fed brain signal might influence economic choice


Can you ever be too rich or too thin is a semi-famous saying. Is there any validity to this statement?

Why did humans invent money? It provides a convenient unit of exchange. And what are the most important things that money is used to purchase; the necessities of life – food and shelter.

Yesterday, I wrote about the possible link between the growing obesity problem in America and the rise of consumer debt. In today’s piece I will start into a possible biological explanation of this link.

In the past we would exchange one form of food for another, or exchange other goods for food. While many of us may think of the gold standard (money backed by an equal worth of gold) however, what is the ‘gold standard’ exchange unit in the brain? At an evolutionary level wealth (be it paper in the wallet, money in the bank, or gold in the safe) at the brain level equates to not being hungry and possibly have a surplus of food supply, or prior to our ability to store food – fat storage. It is only in the relatively recent times (evolutionary speaking) that we were able to store food, before that all there was your fat storage.

Now this link between wealth and not feeling hungry may make intuitive sense to you but is there any studies that support this general idea?

Briers et al., 2006 studied this question in 3 different scenarios. In the first study, one group had not eaten for 4 hours (which is not a long time – just the normal time between meals), and the second group was given a large piece of cake (then filled questionnaires for 20 minutes). When both groups where then given the opportunity to give money to charity the group that was satiated (not hungry) gave more money than the hungry group (had not eaten for 4 hours).

In the second study the group that received olfactory food cues (which increases desire to eat) gave less money than the group that did not receive the olfactory cues.

The final experiment is the most interesting. One group was told to imagine winning a large lottery ($35,000) while the second group imagined winning a very small lottery win ($35). Then both groups were asked to make a list of all the things they were dreaming of buying with their imagined winnings. Finally the groups were  then offered two different bowls of M & Ms in a made up taste test experiment, while what they were really measuring was overall consumption. The group in the high lottery winning group ate more M & Ms (if they excluded restrained eaters that were dieting – so top down processing can make a difference) than the group that only imagined winning aa small amount of money. Now the authors go on to give us a bigger picture understanding of how food and money is tied together in the brain:

Breiter, Aharon, Kahneman, Dale, and Shizgal (2001) found that the orbitofrontal cortex is activated by monetary rewards, whereas O’Doherty, Deichmann, Critchley, and Dolan (2002) found the orbitofrontal cortex to be activated by the consumption and anticipation of sweet-tasting food rewards. The overlap in neural activation suggests a common pathway for processing money and food rewards, and such a common pathway would have major implications for the standard economic perspective on the utility of money… The emerging evidence that these two reward systems share a brain region (e.g., Breiter et al., 2001; O’Doherty et al., 2002) raises the question of the extent to which this region is involved in the processing of all kinds of rewards (Montague & Berns, 2002; Wilson & Daly, 2004). For example, neural evidence suggests that the same dopaminergic reward circuitry in the midbrain is activated for a wide variety of reinforcers, including attractive faces (Aharon et al., 2001), funny cartoons (Mobbs, Greicius, Abdel-Azim, Menon, & Reiss, 2003), cultural objects such as sports cars (Erk, Spitzer, Wunderlich, Galley, & Walter, 2002), drugs (Schultz, 2002), and money (Breiter et al., 2001).

Keep in mind the importance of the dopaminergic reward system for both food and money for future blog pieces.

Does the links between food and money have even wider implications, the authors think so.

Some behavioral evidence is consistent with the proposal that financial and caloric resources are closely entwined. Nelson and Morrison (2005) found that men who feel either poor or hungry prefer heavier women than men who feel rich or satiated. The authors suggested that preference for women’s body weight is determined by the individual’s experience of resource scarcity…Thus, we claim that people are less likely to sacrifice money when they desire food than when they are satiated, and that people eat more when they desire money than when their desire for money is low.

In summary the authors point several interesting ideas:

Money is viewed as a means to obtain biologically relevant incentives (food), and food is viewed as a means of preventing the body’s energy resources from falling below an energy set point… Finally, the symmetric association between food and money may help explain why poor people are especially vulnerable to overeating and have ill health as a result. In industrialized countries such as the United States (Drewnowski & Specter, 2004), as well as in developing countries (James, 2004), obesity is usually associated with poverty. Perhaps in present-day societies, the attraction to money is so powerful that people who, relatively speaking, fail in their quest for (more) money become frustrated. Accordingly, as financial and caloric resources are exchangeable, they might tend to appease their desire for money by consuming more calories than is healthy.

Now there are still a couple of possibilities here – and I have no real answer to the chicken or egg problem at this point. Does the frustration of not consuming (and/or accumulating) money make economically disadvantaged people consume more calories and become overweight/obese to compensate. Or is it also possible that being overweight, which gives a feeling to the body/brain that you are ‘wealthy’ make you less concerned about accumulating money? As with most things it could easily be a bit of both.

The other point to keep in mind to make sense of the above study is you the reader might have thought that overweight people being constantly satiated should be more generous with their money. But I am not sure it works that way, because the reason people are overweight is due to them feeling hungry more often that non-overweight people. On the other hand it is possible that overweight people can not endure the suffering of hungry signals and they constantly are eating to make sure they never get into that state. Slim people feel more satiated during a greater length of time in the average day than those struggling with weight gain and/or they can handle the pain signals of hunger better. I will try to sort this all out in future pieces (if possible) as I get into the biology of the reward system and food.

According to the above cited paper if your brain is getting a fed signal then you are more generous (more altruistic), which is a good thing, but maybe it also means you are just less concerned about money (and hence do not save and go into debt) because your body/mind is telling you that you are ‘wealthy’.

The question though is does being overweight really affect our economic choices – saving money or going into debt? What does this mean for developed or developing countries? What does it mean to you as an individual? Can you hack your basic economic choices by changing your lifestyle?

I will try to answer some of these questions in the near future.

2 comments for “Why a fed brain signal might influence economic choice

  1. JB
    July 22, 2008 at 4:41 pm

    How does this tie in with lower mammals / animals? Without the forebrain but same desires for food. Interesting that humans have this higher center as well as primitive responses of other animals. And that the massive increase in intelligence (and plasticity?) can get hijacked to its detriment.

  2. Ward
    July 24, 2008 at 8:23 am

    Thanks JB,

    for your comment. Good point regarding lower organisms, but these organisms will start hoarding if they undergo calorie restriction. I will have more to say about this in a later post. Some would argue our problem is that our big cortex allowed us to be in the position of unlimited food supply :)