34-2 What cultural and situational factors influence hunger?

Our internal hunger games are indeed pushed by our physiological state—our body chemistry and hypothalamic activity. Yet there is more to hunger than meets the stomach. This was strikingly apparent when Paul Rozin and his trickster colleagues (1998) tested two patients with amnesia who had no memory for events occurring more than a minute ago. If, 20 minutes after eating a normal lunch, the patients were offered another, both readily consumed it … and usually a third meal offered 20 minutes after the second was finished. This suggests that part of knowing when to eat is our memory of our last meal. As time passes since we last ate, we anticipate eating again and start feeling hungry.

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Body chemistry and environmental factors together influence not only the when of hunger, but also the what—our taste preferences. When feeling tense or depressed, do you crave starchy, carbohydrate-laden foods? Are you like ardent football fans who, after a big loss, tend to take solace in high-calorie foods (Cornil & Chandon, 2013)? Carbohydrates boost the neurotransmitter serotonin, which has calming effects. When stressed, both rats and many humans find it extra rewarding to scarf Oreos (Artiga et al., 2007; Sproesser et al., 2014).

Our preferences for sweet and salty tastes are genetic and universal. Other taste preferences are conditioned, as when people given highly salted foods develop a liking for excess salt (Beauchamp, 1987), or when people who have been sickened by a food develop an aversion to it. (The frequency of children’s illnesses provides many chances for them to learn food aversions.)

Culture affects taste, too. Bedouins enjoy eating the eye of a camel, which most North Americans would find repulsive. Many Japanese people enjoy nattó, a fermented soybean dish that “smells like the marriage of ammonia and a tire fire,” reports smell expert Rachel Herz (2012). Although many Westerners find this disgusting, Asians, she adds, are often repulsed by what Westerners love—“the rotted bodily fluid of an ungulate” (a.k.a. cheese, some varieties of which have the same bacteria and odor as stinky feet). Most North Americans and Europeans shun horse, dog, and rat meat, all of which are prized elsewhere.

Rats tend to avoid unfamiliar foods (Sclafani, 1995). So do we, especially animal-based foods. Such neophobia (dislike of things unfamiliar) surely was adaptive for our ancestors, protecting them from potentially toxic substances. Disgust works. Nevertheless, in experiments, people who repeatedly sample an initially novel fruit drink or unfamiliar food typically experience increasing appreciation for the new taste. Moreover, exposure to one set of novel foods increases our willingness to try another (Pliner, 1982, Pliner et al., 1993).

Other taste preferences also are adaptive. For example, the spices most commonly used in hot-climate recipes—where food, especially meat, is at risk of spoiling more quickly—inhibit bacteria growth (FIGURE 34.4). Pregnancy-related nausea and food aversions peak about the tenth week, when the developing embryo is most vulnerable to toxins. So there is biological wisdom to our taste preferences.

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To a surprising extent, situations also control our eating—a phenomenon psychologists have called the ecology of eating. Here are three situations you may have noticed but underestimated: