Eating behaviour

11.1 · Free notes

Explanations for food preferences: evolutionary and learned (social, cultural, conditioning)

Key points

• Food preferences are explained by evolved predispositions (nature) and learning (nurture); AQA expects both to be described and evaluated, and their interaction to be recognised.
• Evolutionary explanation: humans prefer sweet and fatty (energy-dense) foods because energy was scarce in the environment of evolutionary adaptedness (EEA). Fat gives about 37 kJ/g, against about 17 kJ/g for carbohydrate or protein, and sweetness signals safe, ripe fruit.
• Neophobia is the avoidance of unfamiliar foods. It is adaptive because novel foods might be toxic, and it peaks in early childhood (about 2–6 years) when children become mobile and less supervised. It declines with age and repeated exposure.
• Conditioned taste aversion (Garcia effect): after one pairing of a taste with illness, the taste is avoided. Aversion can form despite a delay of hours between food and sickness. Garcia et al. (1955) showed this in rats, supporting biological preparedness.
• Social learning: children acquire preferences by observation and modelling of parents and peers. In Birch (1980), preschoolers shifted their vegetable preferences towards those of peers they sat with.
• Mere exposure: repeated, small, pressure-free tastes of a novel food increase liking. Birch and Marlin (1982) found that 2-year-olds' preference rose with the number of exposures (up to 10), and a single exposure was not enough.
• Cultural influences: culture determines which foods are available, acceptable and prestigious, for example insects eaten in parts of Asia and Africa. Flavours also pass through amniotic fluid and breast milk (Mennella et al., 2001: carrot juice), so early exposure shapes later culturally typical preferences.
• Classical conditioning: a neutral flavour (NS) paired with a pleasant outcome such as sugar or calories (UCS) becomes a conditioned stimulus that is liked (flavour-nutrient learning). Operant conditioning: food used as a reward increases liking, while using a food as the 'means' to a reward, or pressuring a child to eat it, reduces liking (Birch et al., 1984).
• Evaluation (evolutionary): it is plausible and has cross-species support, but it is hard to test (EEA conditions cannot be recreated), it is deterministic, and it cannot explain wide cultural and individual variation. Much of the evidence comes from animals.
• Evaluation (learning): experimental studies of children give good evidence for cause and effect, but samples are small, often from the USA, and based on short-term lab measures. A full account must combine both explanations, because biology sets the predispositions and experience modifies them.

In more detail

• Worked taste aversion: a student eats prawns and gets food poisoning hours later. Afterwards the smell of prawns makes them feel sick, even if the prawns were not the cause.
• Repeated tasting: Wardle et al. (2003) found that giving children a small taste of a disliked vegetable (red pepper) every day for 8 days increased both liking and how much they ate.
• Bitter tastes: disliking bitter tastes may be adaptive, because many poisons are bitter; children and pregnant women are especially sensitive.
• Learning to like chilli: chilli is unpleasant at first, but in cultures where it is common, children gradually learn to enjoy it through repeated exposure and copying their families (Rozin).