In the first task, participants rated various foods from chips to candy bars for taste and personal preference. This apparent preference test disguised a task that measured how much participants ate when food was freely available.
In the second task, participants could swivel between two computer stations. Pressing specified keys on one earned points to eat their favorite food; pressing keys on the other earned points to read a newspaper.
The resulting behavioral measures included calories consumed as energy in kilocalories, reflecting both amount and caloric density, and time spent earning food instead of the opportunity to read the news.
Both obesity and the genotype associated with fewer dopamine D2 receptors predicted a significantly stronger response to foods reinforcing power. Perhaps not surprisingly, participants with that high level of food reinforcement consumed more calories.
The results also revealed a three-rung ladder of consumption, with people who dont find food that reinforcing, regardless of genotype, on the lowest rung. On the middle rung are people high in food reinforcement without the A1 allele. Atop the ladder are people high in food reinforcement with the allele, a potent combination that may put them at higher risk for obesity.
The reinforcing value of food, which may be influenced by dopamine genotypes, appeared to be a significantly stronger predictor of consumption than self-reported liking of the favorite food. Whats more, obese participants clearly found food to be more reinforcing than non-obese participants. The authors conclude that, Food is a powerful reinforcer that can be as reinforcing as drugs of abuse.
Researchers still view reinforcement as one of several factors that motivate eating behavior, but the present study highlights the genetic contribution and role of reinforcement. In theory, people producing less dopamine may, as a r
|Contact: Pam Willenz|
American Psychological Association