Brief report: Can contingent imitation reinforce truck lifting in a three-month-old infant?

Abstract

Infant leg lifting is a well-researched operant response and now forms the basis of many childhood activities. Contingent imitation is a process where the trainer often will imitate the activities of the subject and attempt to get an increase in those activities. Gradually in the contingent imitation procedure variation is introduced in an attempt to get the subject to reciprocate the imitation process by incorporating it into the behavioral routine. This study explores the first part of the contingent imitation exercise- can contingent imitation increase trunk lifting in a three-month-old infant. We used an ABA design to explore this phenomenon. In the first phase, the infant was placed on a bed where the number of spontaneous lifts was recorded over a 90 second period. In the next phase the experimenter lay next to the infant and imitated all the infants' motor behavior. Only the number of lifts of the legs raising the trunk was recorded, since it was the easiest behavior to clearly mark occurrence. Contingent on the infants lifting of the legs and trunk, the experimenter would lift their legs and trunk. This was recorded over a 90 second interval. In the final phase, the experimenter left the room for 90 seconds and the number of lifting was recorded. In the baseline phase the infant averaged 3 lifting in a thirty second period, during intervention lifting rate went to approximately an average of 4-lifts/ thirty-minute intervals. In the return to backline phase, the infant averaged 2lifts/ 30-second intervals. These results support the use of contingent imitation to serve as reinforcement for infants trunk lifting. Key words: contingent imitation, leg and trunk lifting, infant operant response ********** Infants are known to respond from birth to primary reinforcers. A variety of primary reinforcers exist to meet infant's basic biological needs. For example, both human and nonhuman infants are poor thermo-regulators, so closeness to parent skin from birth provides reinforcing qualities. Sensory-ecological reinforcers (Novak & Paleaz, 2005) are also apparent at very early age. For example, Harlow (1958) discovered that soft items were reinforcing over hard items for neonatal macaque monkeys. Contingent imitation (Gazdag, & Warren, 2000) is a process in which the trainer will imitate a child's behavior. After repeated episodes, the trainer will then introduce a 5% variation in the cycle in attempt to get the child to imitate the change. For contingent imitation to be effective the response being imitated has to serve as a sensory reinforcer to increase the frequency of responding. This study attempts to determine if imitation of a child's response can reinforce that response in a three-month-old infants. Thus, imitation of a child's trunk and buttocks lift would need to increase the frequency of trunk and buttocks lifting for the child. Previous research has shown that three month old infants' leg movements readily come under control of operant ecological reinforcement (Merriman, Rovee-Collier, & Wilk, 1997). METHODS Subject Subject was born at 9lbs and 15 ounces. She was 22 inches at birth. This placed her in the 99%ile for weight and the 98%ile for height. At the time of the study the subject was 3 months old, 25 inches in length and weighed 17 lbs. The subject was no stranger to leg movements for reinforcement (see Dziewolska & Cautilli, 2005; Cautilli & Dziewolska, 2005). In addition, since approximately 6 weeks old, the subject used a kick and play chair, which presents reinforcement in the form of lights and music when the child kicks. Design Since this infant had a lot of experience with kicking to produce reinforcement, it was decided for this study a more complex and physically difficult response would be chosen: trunk lift. A trunk lift was defined as when the infant was lying in the supine position a complete lifting of the legs and buttocks off of the floor. …