In The Crowd, Le Bon examines the various characteristics of crowd psychology: "impulsiveness, irritability, incapacity to reason, the absence of judgment of the critical spirit, the exaggeration of sentiments, and others..." He believes "that an individual immersed for some length of time in a crowd soon finds himself - either in consequence of magnetic influence given out by the crowd or from some other cause of which we are ignorant - in a special state, which much resembles the state of fascination in which the hypnotized individual finds himself in the hands of the hypnotizer.".This Crowd Psychology has been applied to modern investing, product development and social media development. Gustave Le Bon was a French social psychologist, sociologist, anthropologist, inventor, and amateur physicist. His writings incorporate theories of national traits, herd behavior and crowd psychology. He is best known for this work, The Crowd: A Study of the Popular Mind.