Repeatability of the infant food reinforcement paradigm: Implications of individual and developmental differences.

The relative reinforcing value of food versus engagement in other behaviors may be related to the development of obesity, and interventions to reduce FRR may prevent the development of obesity. Our laboratory recently developed a paradigm to measure the reinforcing value of food versus an alternative behavior (i.e., playing with bubbles) in infants using a computerized laboratory task, during which infants press a button to earn reinforcers following a progressive ratio schedule of reinforcement. The primary purpose of this study was to examine the short-term (within 2 weeks) repeatability of this measure, specifically the outcome of infant food reinforcing ratio (FRR), or how hard infants will work for food relative to the alternative. The secondary aim was to examine whether infant age and temperament dimensions related to novelty responsiveness (high intensity pleasure and approach) moderated the repeatability of FRR. Thirty-seven infants aged 9-18 months completed this study. Repeated measures analysis of variance (ANOVA) showed no differences between time 1 and time 2 in responding for food (F = 0.463, p = 0.501), bubbles (F = 1.793, p = 0.189), or overall FRR (F = 0.797, p = 0.378). Regression models showed the association between BUB Pmax at time 1 and time 2 were moderated by infant age (p = 0.04), with greater repeatability in older infants. Linear regression models also demonstrated that the infant temperamental dimension of high intensity pleasure significantly predicted BUB Pmax at time 1 (ß = 2.89, p = 0.01), but not at time 2. Overall, our findings support the repeatability of this measure for food portion of the reinforcement task, but demonstrated that the measure of non-food portion of the task required modification, in particular among children younger than 13 months old.

Infant Temperament Is Associated with Relative Food Reinforcement.

OBJECTIVE: Food reinforcement refers to how hard someone is motivated to work to gain access to food. Infant temperament is defined as behavioral styles, or constitutionally based individual differences in reactive and regulatory aspects of behavior. Identifying correlates of food reinforcement, such as infant temperament, may help identify infants at risk for future negative health consequences (e.g., overweight or obesity) of high food reinforcement. METHODS: This study tested aspects of parent-reported negative reactivity and regulation and their associations with relative food reinforcement in a cross-sectional sample of 105 9- to 18-month-old infants. Hierarchical linear regression models were then used to predict infant food reinforcement for the temperament dimensions that were significantly related to it. RESULTS: Two temperament dimensions, cuddliness (regulatory aspect) (B = -0.050, ΔR2 = 0.074, p = 0.005) and rate of recovery from distress and arousal (reactive aspect) (B = -0.040, ΔR2 = 0.045, p = 0.031), were inversely associated with relative food reinforcement. CONCLUSION: Clarifying the nature of relationships between these two behavioral predictors, infant temperament and relative food reinforcement, and early obesity can elucidate the role of individual differences in early obesity risk and can further inform targets for early behavioral obesity preventive interventions.

Reducing relative food reinforcement in infants by an enriched music experience.

OBJECTIVE: The reinforcing value of food may be established early in life. Research shows that infant weight status is related to the relative reinforcing value of food versus non-food alternatives (food reinforcing ratio, FRR). The purpose of this pilot study was to assess the effects of a 6-week music enhancement program (Music Together®, n = 14) versus an active play date control group (n = 13) on the FRR in 9- to 16-month-old infants who were high in relative food reinforcement. METHODS: Participating parents and infants attended six weekly 45-min group classes. Parents in the music group and the play date group were encouraged to listen to the Music Together program CD or play with the play date group's toy with their infants at home, respectively. RESULTS: Intent-to-treat analysis showed a decrease in FRR for infants in the music group (mean ± SD: -0.13 ± 0.13) in comparison to a slight increase in the control group (0.04 ± 0.11) (F[1, 24] = 11.86, P = 0.002). CONCLUSIONS: These findings provide evidence that relative reinforcing value of food can be reduced by promoting alternative reinforcers at an early age.