"Psychology for Beginners" Hereward Carrington Ph.D., (No. 491 - Little Blue Book)
 
This foundational text introduces readers to the essential principles of psychology, exploring the nature of consciousness, sensation, perception, memory, and emotion through clear and accessible explanations. Carrington’s work also explains connections between mental processes and behavior, offering early insights into topics such as attention deficient, learning, and the subconscious mind.