Two-year-old Eli dislikes green vegetables and often refuses to eat them.

Part A

• Point 1 — Evolutionary psychology—Evolutionary psychologists believe that human behavior is motivated by the desire to ensure the survival and proliferation of our genes. By age two, children are able to move about on their own and will therefore encounter new plants, some of which may look like vegetables but, in fact, be dangerous to eat. Therefore, an evolutionary psychologist might say that Eli’s refusal to eat green vegetables is due to a natural avoidance that arises about the time children become independent enough to eat things without supervision.
• Point 2 — Erickson’s psychosocial stage theory—According to Erikson, from ages one to three children are in a stage that revolves around a conflict between autonomy or shame and doubt. As such, children of this age often try to assert their will, and the word no becomes a common part of their vocabularies. Eli’s refusal to eat the green vegetables his parents so desperately want him to eat may therefore just be a way of asserting his independence.

Part B

• Point 3 — Mere exposure effect—The mere exposure effect says that the more one is exposed to something, the more one comes to like it. Therefore, Eli’s parents could simply serve him green vegetables frequently hoping that with repeated contact, he will come to like them more.
• Point 4 — Eli’s lack of Piagetian conservation—According to Piaget, children learn to conserve upon entering the concrete operations stage around age six. Until then, children are typically unable to solve problems that ask them to compare quantities. Eli’s parents may be able to take advantage of this cognitive limitation in how they present his vegetables. For instance, instead of serving Eli many small pieces of celery, they could ask Eli to eat just one (large) celery stalk.
• Point 5 — Conformity—People have a natural desire to fit in with others. If Eli’s siblings or cousins or friends eat green vegetables, Eli’s parents may be able to increase his consumption of vegetables by serving them to Eli among a group of people all of whom will eat their green vegetables.
• Point 6 — Modeling—Modeling is when someone observes someone else’s behavior and then copies it. While conformity involves fitting into a group, modeling can be done by an individual. Eli’s parents can model eating green vegetables themselves hoping that Eli will notice and copy them.
• Point 7 — Positive reinforcement—A reinforcer is a consequence that increases the likelihood of a behavior. Eli’s parents can use positive reinforcement by giving Eli something he wants when he eats his green vegetables. For instance, each day that Eli finishes his vegetables he could be rewarded with a half hour of watching television.

Part C

• Point 8 — I recommend capitalizing on the mere exposure effect. Because exposure actually increases liking, it will hopefully result in a long-term change in Eli’s vegetable-eating behavior.