Wundt's research was not reliable. This is because introspection focuses on subjective experiences, meaning that findings varied greatly from person to person, making it difficult to establish consistent general principles of human behaviour. Behaviourist psychologists, like Watson, believed Psychology should only study behaviour that could be observed and measured scientifically. Therefore, the behaviourist approach was born which used more empirical and objective methods, such as controlled lab experiments, to study human behaviour, increasing the scientific status of Psychology.