Consider your textbook's unifying theme that "psychology is empirical." What does this theme imply that psychologists base their conclusions on

A)  logical reasoning
B)  direct observations 
C)  speculation
D)  common sense

The unifying theme that "psychology is empirical" implies that psychologists base their conclusions on direct observations, meaning they collect data through systematic and objective measures. Logical reasoning, speculation, and common sense may be used to generate hypotheses or ideas, but they must be tested through empirical research before they can be considered valid conclusions.