Final answer:
Dr. Willard is using the ecological approach to study infant siblings, which means observing them in their natural environment, specifically their home, to understand their behavior in real-life settings.
Step-by-step explanation:
Dr. Willard's research approach aligns with the ecological approach, which emphasizes observation in the participants' natural environment. This means that Dr. Willard is studying the interactions of infant siblings within their home setting where their behaviors are more likely to reflect their true nature, as opposed to a controlled or artificial setting. This approach underscores the importance of studying individuals in the context of their real-life environments to better understand the dynamic interactions between organisms and their surroundings. Naturalistic observations, as used in developmental psychology and ecological studies, are crucial to understanding the interplay between genetic makeup, behavior, and environmental influences, which can all contribute to the development and socialization of individuals.