An ABAC comparison of two intensive interventions for food refusal.

An ABAC comparison of two treatment packages for food refusal, physical guidance and nonremoval of the spoon, was conducted with two children with limited food acceptance. Both of these treatment packages included prevention of escape from presented food. Subsequent to baseline, one of the two treatment packages was implemented for each child. The treatment packages were implemented ABAC for one child and ACAB for the other child. Once the percentage of bites accepted had increased to at least 75% with the initial exposure to a treatment package, that treatment was withdrawn with a subsequent exposure to the second treatment package. The results indicated that both treatment packages were effective in establishing food acceptance. Also, initial exposure to either of the two treatment packages facilitated acquisition of food acceptance during the second exposure. Parental preference of the treatment package may have been influenced by the order of exposure to the treatment conditions.

An assessment of food acceptance in children with autism or pervasive developmental disorder-not otherwise specified.

Some children with autism and pervasive developmental disorder-not otherwise specified (PDD-NOS) have been reported to have atypical feeding behavior, such as sensitivity to food texture and selective preferences for particular foods. No systematic studies of feeding behavior in this population have been published. Munk and Repp (1994) developed methods for assessing feeding problems in individuals with cognitive and physical disabilities that allow categorization of individual feeding patterns based on responses to repeated presentations of food. In this study, we systematically replicated the Munk and Repp procedures with children with autism and PDD-NOS. Thirty children, ages 3 to 14 years, were exposed to 12 food items across 6 sessions. Food acceptance, food expulsion, and disruptive behavior were recorded on a trial-by-trial basis. Approximately half of the participants exhibited patterns of food acceptance, indicating selectivity by food category or food texture. Others consistently accepted or rejected items across food categories. Whether these patterns of food acceptance are atypical remains to be determined by comparison with the feeding patterns of typically developing children and other children with developmental delays.

A comparison of verbal and tangible stimulus preference assessments.

Tangible preference assessments were compared with verbal preference assessments for 6 individuals with mental retardation, behavior disorders, or both. In the tangible assessment, items were placed in front of the participant. In the verbal assessment, participants were asked, "Do you want X or Y?" and the items were not present. The two assessments yielded similar high-preference items for 4 of the 6 participants. The verbal assessment was typically completed in less time than the tangible assessment.

Effects of reinforcer choice measured in single-operant and concurrent-schedule procedures.

The effects of choice and no choice of reinforcer on the response rates of 3 children with autism were compared across single-operant and concurrent-schedule procedures. No consistent differences in responding between choice and no-choice components emerged during single-operant phases. During the concurrent-schedule phases, however, all participants had substantially higher rates of responding to the button that led to a choice among reinforcers than to the button that did not lead to choice.

Pigeons' choices between fixed-ratio and linear or geometric escalating schedules.

Four related procedures provided a basis for comparing the linear-optimality principle with a principle based on the sums of reciprocals of distances to reinforcement, and to explore the generality of the sums-of-reciprocals principle as a description of choice patterns in situations of diminishing returns. The procedures all arranged choices between fixed-ratio schedules and progressive-ratio schedules, which escalated with each consecutive choice. In contrast to previous work that involved constant ratio increments, two sets of procedures in this study involved relatively small increments that are similar to the early values when a progressive schedule is increasing proportionally. The remaining two sets of procedures examined progressive schedules with proportional increments. In addition, the initial value of the progressive alternative was manipulated to determine its effects on patterns of choice with both linear and proportional types of escalation. With the exception of one phase, regardless of the initial/reset value and the patterns of escalation, patterns of choice with pigeons were well characterized by the sums-of-reciprocals principle. This supports previous research with pigeons using fixed-increment progressive schedules, as well as situations in which the progressive schedule increased by constant proportions instead of by constant increments. The findings are attributed to the feature of this averaging technique whereby it differentially values reinforcers based on their relative proximity to a particular choice point.

The relationship between food refusal and self-injurious behavior: a case study.

Food refusal and self-injurious behavior often co-occur in children with developmental disabilities and mental retardation. The subject of the case study was a 3-yr-old boy with food refusal, self-injurious behavior and developmental delay. Using an alternating treatment design, positive reinforcement for acceptance combined with either nonremoval of the spoon or guidance for refusal increased food acceptance and resulted in a decrease in self-injurious behavior despite not being targeted. Although the contingencies for acceptance, refusal and self-injurious behavior remained constant, self-injurious behavior increased with an increase in grams consumed. A combined treatment of positive reinforcement for acceptance, guidance for refusal, position change and gastrojejunal feedings resulted in a decrease in self-injurious behavior and an increase in grams consumed.

Preference between variable-ratio and fixed-ratio schedules: local and extended relations.

Although it has repeatedly been demonstrated that pigeons, as well as other species, will often choose a variable schedule of reinforcement over an equivalent (or even richer) fixed schedule, the exact nature of that controlling relation has yet to be fully assessed. In this study pigeons were given repeated choices between concurrently available fixed-ratio and variable-ratio schedules. The fixed-ratio requirement (30 responses) was constant throughout the experiment, whereas the distribution of individual ratios making up the variable-ratio schedule changed across phases: The smallest and largest of these components were varied gradually, with the mean variable-ratio requirement constant at 60 responses. The birds' choices of the variable-ratio schedule tracked the size of the smallest variable-ratio component. A minimum variable-ratio component at or near 1 produced strong preference for the variable-ratio schedule, whereas increases in the minimum variable-ratio component resulted in reduced preference for the variable-ratio schedule. The birds' behavior was qualitatively consistent with Mazur's (1984) hyperbolic model of delayed reinforcement and could be described as approximate maximizing with respect to reinforcement value.

An alternating treatments comparison of two intensive interventions for food refusal.

We compared two treatment packages involving negative reinforcement contingencies for 3 children with chronic food refusal. One involved physically guiding the child to accept food contingent on noncompliance, whereas the other involved nonremoval of the spoon until the child accepted the presented food. Subsequent to baseline, an alternating treatments comparison was implemented in a multiple baseline design across subjects. After each child had been exposed to at least nine sessions of each treatment condition and percentage of bites accepted had increased to at least 80%, the child's caregivers selected the preferred treatment package. The results indicated that both treatments were effective in establishing food acceptance. However, physical guidance was associated with fewer corollary behaviors, shorter meal durations, and parental preference.

The costs of eating: a behavioral economic analysis of food refusal.

Behavioral economic concepts were applied to the analysis and treatment of pediatric feeding disorders in a clinical setting. In Experiment 1, children who chronically refused food were presented with varying amounts of food on a spoon (empty, dipped, quarter, half, and level). Each child exhibited a different but orderly demand function of response (acceptance, expulsion, and mouth clean) by cost (increasing spoon volume) for a constant pay-off of toys and social interaction. In Experiment 2, physical guidance or nonremoval of the spoon for food refusal was initiated at the smallest spoon volume with low levels of acceptance, and was subsequently introduced at the largest spoon volume with moderate levels of acceptance. Treatment was effective in increasing acceptance, and these effects generalized hierarchically across untargeted spoon volumes. The results of both studies provide preliminary support that increasing spoon volume can be equated conceptually with increasing response effort, and that the change from differential reinforcement to physical guidance or nonremoval of the spoon appears to have altered the elasticity of each child's demand function.