Peter Gray's Psychology has become a favorite of instructors with its exploration of psychology's major theories, and the evidence that supports and refutes these theories.  Each edition incorporates an exceptional amount of contemporary research, encouraging students to probe for the purposes and biological origins of behavior--the "whys" and "hows" of human psychology.  Peter Gray's engaging, readable writing style makes the science of psychology, and its interactions with biology, accessible and meaningful.  With the new edition, Gray has taken care to ensure that his comprehensive, thought-provoking, and contemporary coverage is well-attuned to the needs and interests of today's students.