The development of psychological theories from the Renaissance to today can be divided into several important time periods:

1. The Renaissance (14th-17th centuries):

   • This time focused on humanism, which means valuing individual people.
   • Philosophers like Descartes suggested that the mind and body are separate things.

2. Enlightenment (17th-19th centuries):

   • Reason and scientific thinking became very important.
   • This period saw the start of real research. For example, Galton worked with statistics, helping to measure psychological aspects.
   • By 1900, only 1 in 10 Americans thought psychology should be considered a science, influenced by Dewey's ideas.

3. Early 20th Century:

   • Behaviorism came into the picture, with researchers like Watson and Skinner focusing on what people do, instead of what they think.
   • In 1913, Watson made behaviorism a key area of psychology.

4. Mid-20th Century:

   • The Humanistic approach became popular, with Maslow introducing his hierarchy of needs in the 1940s.
   • By 1961, 66% of U.S. psychologists identified with humanistic ideas.

5. Late 20th Century to Today:

   • Cognitive psychology became important, focusing on how we think and process information.
   • By 2015, 45% of psychologists were using cognitive-behavioral techniques.

In short, psychological theories have changed from just ideas and thoughts to more research-based and combined methods. This shows how our understanding of human behavior and thinking continues to grow and develop.