The double blind procedure was developed by researchers because of which unifying theme in psychology

A)  Psychology is empirical. 
B)  Psychology evolves in a sociohistorical context. 
C)  Our behaviour is shaped by our cultural heritage. 
D)  Our experience of the world is highly subjective.

The double-blind procedure was developed to minimize the effects of biases and expectations, both from the participants and the researchers, acknowledging that our perceptions and experiences can significantly influence outcomes in psychological research. This method ensures that neither the participants nor the experimenters know who is receiving a particular treatment, thus reducing subjective bias and increasing the reliability of the results.