Final answer:
Sarah's father is using positive reinforcement, a type of behavioral conditioning, by rewarding his children's good behavior with a trip to the movies.
Step-by-step explanation:
When Sarah and her brother are well behaved and their father takes them to the movies as a result, their father is using a form of behavioral conditioning known as positive reinforcement. This type of training is where a behavior is encouraged by rewarding it. In this case, the pleasant experience of going to the movies is the reward for their good behavior, which increases the likelihood that they will behave well in the future.
This technique is a component of social learning and is part of what the family, as the primary agent of socialization, uses to teach children the acceptable ways of thinking and behaving in line with social and cultural norms. While positive punishment can also be used to influence behavior, it can have negative effects. Therefore, rewarding good behavior with positive experiences or items, which is enacted by Sarah's father, is generally favored in modern parenting advice.