IVAN PAVLOV(1849 - 1936) Russian physiologist known for his momentous studies of reflex behavior, specifically the conditioned and unconditioned reflexes in dogs which greatly influenced the development of behavioral psychology in the early twentieth century. Rare and important signed book, his seminal work Conditioned Reflex Twenty Years of Objective Study of the Higher Nervous Activity of Animals, Lenogiz, Leningrad, 1932, fifth edition, boldly inscribed on the verso of the frontis portrait: "To the most honorable Boris Dmitrievich Nakhodkin from the Author 21 November 1932", essentially making this a signed photo. Front flyleaf is detached, binding loose and spine a bit worn, else boldly penned and generally very good.