Origins of food reinforcement in infants.
BACKGROUND
Rapid weight gain in infancy is associated with a higher risk of obesity in children and adults. A high relative reinforcing value of food is cross-sectionally related to obesity; lean children find nonfood alternatives more reinforcing than do overweight/obese children. However, to our knowledge, there is no research on how and when food reinforcement develops.


OBJECTIVE
This study was designed to assess whether the reinforcing value of food and nonfood alternatives could be tested in 9- to 18-mo-old infants and whether the reinforcing value of food and nonfood alternatives is differentially related to infant weight status.


METHODS
Reinforcing values were assessed by using absolute progressive ratio schedules of reinforcement, with presentation of food and nonfood alternatives counterbalanced in 2 separate studies. Two nonfood reinforcers [Baby Einstein-Baby MacDonald shows (study 1, n = 27) or bubbles (study 2, n = 30)] were tested against the baby's favorite food. Food reinforcing ratio (FRR) was quantified by measuring the reinforcing value of food (Food Pmax) in proportion to the total reinforcing value of food and a nonfood alternative (DVD Pmax or BUB Pmax).


RESULTS
Greater weight-for-length z score was associated with a greater FRR of a favorite food in study 1 (FRR-DVD) (r = 0.60, P < 0.001) and FRR of a favorite food in study 2 (FRR-BUB) (r = 0.49, P = 0.006), primarily because of the strong association between greater weight-for-length z score and lower DVD Pmax (r = -0.71, P < 0.0001) and BUB Pmax (r = -0.53, P = 0.003). Infant monthly weight gain was positively associated with FRR-DVD (r = 0.57, P = 0.009) and FRR-BUB (r = 0.37, P = 0.047).


CONCLUSIONS
Our newly developed paradigm, which tested 2 different nonfood alternatives, demonstrated that lean infants find nonfood alternatives more reinforcing than do overweight/obese infants. This observation suggests that strengthening the alternative reinforcers may have a protective effect against childhood obesity.
From the Division of Behavioral Medicine, Department of Pediatrics, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY (KLK, DMF, and LHE), and the Research Institute on Addictions, State University of New York at Buffalo, Buffalo, NY (RDE).
Kai Ling
KL
Kong
From the Division of Behavioral Medicine, Department of Pediatrics, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY (KLK, DMF, and LHE), and the Research Institute on Addictions, State University of New York at Buffalo, Buffalo, NY (RDE).
Denise M
DM
Feda
From the Division of Behavioral Medicine, Department of Pediatrics, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY (KLK, DMF, and LHE), and the Research Institute on Addictions, State University of New York at Buffalo, Buffalo, NY (RDE).
Rina D
RD
Eiden
From the Division of Behavioral Medicine, Department of Pediatrics, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY (KLK, DMF, and LHE), and the Research Institute on Addictions, State University of New York at Buffalo, Buffalo, NY (RDE).
Leonard H
LH
Epstein
D002657:Child Development; D004435:Eating / Q000523:psychology*; D005247:Feeding Behavior; D005260:Female; D005518:Food Preferences / Q000523:psychology; D006801:Humans; D006963:Hyperphagia / Q000453:epidemiology / Q000517:prevention & control / Q000523:psychology*; D007223:Infant; D018730:Infant Behavior; D007225:Infant Food; D007227:Infant Nutritional Physiological Phenomena; D008297:Male; D009518:New York / Q000453:epidemiology; D010865:Pilot Projects; D010988:Play and Playthings / Q000523:psychology; D012054:Reinforcement, Psychology; D012307:Risk Factors; D014741:Video Recording; D015430:Weight Gain
enriched environment; food reinforcement; infancy; non-food reinforce; obesity