Final answer:
Psychologist William James, associated with functionalism, emphasized studying the function of behavior in the environment and how mental activities help organisms adapt, moving psychology toward problem-solving and away from the introspection focus of structuralism.
Step-by-step explanation:
William James is the psychologist who believed that psychology's purpose was to study the function of behavior in the world, and his perspective is known as functionalism. Functionalism led psychology towards a focus on how mental activities helped an organism adapt to its environment by solving problems. This approach was informed by Charles Darwin's theory of evolution, emphasizing that adaptive behaviors are those that have been naturally selected because they aid survival and reproduction.
Unlike structuralism, which aimed to understand the structure of the mind through introspection, functionalism was more interested in the practical applications of mental processes and their role in enabling an organism to thrive within their environment. William James also utilized more objective measures than introspection alone, including various recording devices and the examination of concrete products of mental activities, giving psychology a more empirical approach.