These comprehensive databases contain articles on psychology topics.
To find articles that report on empirical research, some keywords you might want to use could be:
population, study, results, discussion, data, variables, limitations, implications, survey, respondents, or conclusion.
Such terms should be searched as keywords rather than subject terms because they reflect the kind of language used in an article describing empirical research, but they are not the topic or subject of the study.
Animal learning from Thorndike to Skinner (1980s). The focus of study includes the basic principles of classical and operant conditioning, punishment, reinforcement, and stimulus control. Application to human learning is made.