Watson came out with major contributions to behaviorism. He explained thinking in his own way. According to him, language and thinking were a form of behavior, which he explained with the help of an example.
He said that saying is nothing but a type of behavior. Speaking overtly or to oneself, like when a person is contemplating, is as objective a type of behavior as baseball. According to him, language is a type of overt behavior.
He also claimed that thinking is simply an internal or a sub vocal speech. It is known that overt speech is formed by considerable movement of larynx and tongue. Watson came out with another observation that thought accompanies minute movements of the tongue and larynx.
He explained the evolution of the implicit speech from overt behavior extensively. Hence, Watson correlated thinking and language to behavioristic approach and claimed that both are behaviors only.