Final answer:
Don Baer adjusted the contingency of reinforcement to highlight the role of attention in Marilla's modeled imitations, within the framework of Bandura's observational learning theory.
Step-by-step explanation:
Don Baer changed the contingency of reinforcement to show the importance of attention for Marilla's modeled imitations. This relates to Bandura's concept of vicarious reinforcement within the observational learning framework. In observational learning, attention is paramount as the first step in the modeling process, which is preceded by retention, reproduction, and finally, motivation, according to Bandura's theory. Vicarious reinforcement occurs when an observer is more likely to imitate a model's behavior after seeing the model being rewarded. The contingency of reinforcement, the condition under which the reinforcement is delivered, is crucial for ensuring that the modeled behavior is learned and repeated.