Final answer:
Friends become more alike due to principles of modeling and observational learning in social learning theory, rather than through operant conditioning. They imitate behaviors that are positively reinforced.
Step-by-step explanation:
Friends may become more alike over time during childhood through principles such as modeling, as described by social learning theory. This concept, introduced by Albert Bandura, suggests that children learn behaviors and form their personalities through observational learning. They watch the actions of others and the resulting outcomes, and they tend to imitate behaviors that are positively reinforced.
While operant conditioning, another learning process described by B. F. Skinner involves learning from the consequences of our actions, it is not the primary mechanism by which friends influence each other. However, behaviors that lead to positive outcomes, such as social acceptance and shared enjoyment, could be strengthened among friends through mutual reinforcement.