30-2 What cultural and situational factors influence hunger?

Our internal hunger games are pushed by our body chemistry and brain activity. Yet there is more to hunger than meets the stomach. This was strikingly apparent when trickster researchers tested two patients who had no memory for events occurring more than a minute ago (Rozin et al., 1998). If offered a second lunch 20 minutes after eating a normal lunch, both patients readily consumed it … and usually a third meal offered 20 minutes after they finished the second. This suggests that one part of our decision to eat is our memory of the time of our last meal. As time passes, we think about eating again, and those thoughts trigger feelings of hunger.

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Body cues 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 tend to take solace in high-calorie foods, as has been found in ardent football fans after a big loss (Cornil & Chandon, 2013)? The carbohydrates in pizza, chips, and sweets help boost levels of 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, but conditioning can intensify or alter those preferences. People given highly salted foods may develop a liking for excess salt (Beauchamp, 1987). People sickened by a food may develop an aversion to it. (The frequency of children’s illnesses provides many chances for them to learn to avoid certain foods.)

Our culture teaches us that some foods are acceptable but others are not. 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).

But there is biological wisdom to many of our taste preferences. For example, in hot climates (where foods spoil more quickly) recipes often include spices that inhibit bacteria growth (FIGURE 30.4). Pregnancy-related food dislikes—and the nausea associated with them—peak about the tenth week, when the developing embryo is most vulnerable to toxins.

Rats tend to avoid unfamiliar foods (Sclafani, 1995). So do we, especially those that are animal-based. This neophobia (dislike of unfamiliar things) surely was adaptive for our ancestors by protecting them from potentially toxic substances. Disgust works. In time, though, most people who repeatedly sample an initially novel fruit drink or unfamiliar food come to appreciate the new taste (Pliner, 1982, Pliner et al., 1993).

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