C. Lloyd Morgan (1852-1936) was Romanes’ successor. Morgan recognized the limitations of Romanes’ procedures and conclusions and applied more careful and objective naturalistic observation methods to the study of animal behavior and intelligence. He even continued to use Romanes’ introspection by analogy procedure, but was cautious about the conclusions that he drew from his observations.
Morgan cautioned against too easily accepting higher-order explanations, such as consciousness and intelligence in animals, when lower-order explanations, such as habit or instinct, can suffice. This admonishment to researchers to be parsimonious--that is, being careful, even “stingy” with interpretations--is known as the law of parsimony or Lloyd Morgan’s Canon, and this principle applies across all sciences.
As described by Schultz and Schultz (2008), Morgan was the first psychologist to conduct extensive research on animal behavior. Morgan’s general conclusions were that most animal behavior is the result of learning through associations based on sensory experiences, rather than the operation of higher-order intelligence. We can see here the early formulations that led to modern comparative psychology, which later influenced the development of behaviorism in the 20th Century.