University of California Seal

Mark Rosenzweig


Mark R. Rosenzweig

Professor of Psychology, Emeritus

UC Berkeley

1922 – 2009


Mark R. Rosenzweig, a professor emeritus of psychology at the University of California, Berkeley, whose early studies paved the way for today’s recognition of the brain’s ability to grow and to repair itself, died at his home in Berkeley on July 20, 2009, from kidney failure. He was 86.


A prolific researcher, writer and French-speaking internationalist, Mark collaborated with some of the greatest minds in neuropsychology at Harvard University, UC Berkeley and the Louis Pasteur University in Strasbourg, France. At Berkeley, Mark Rosenzweig collaborated with biochemist Ed Bennett, psychologist David Krech and neuroanatomist Marian Diamond on studies that provided early evidence of brain plasticity, the now well-established notion that neural pathways change throughout our lives as we grow and learn. In addition, his earlier research into auditory perception also laid the groundwork for modern, noninvasive hearing tests.


“Mark Rosenzweig’s investigations were rigorous, groundbreaking and continue to be cited in all current accounts of brain development and plasticity, though they were conducted over half a century ago,” said Stephen Hinshaw, chair of UC Berkeley’s Department of Psychology. “If anyone deserves the term ‘pioneer,’ he does.”


Through extensive studies of laboratory rats at UC Berkeley in the 1950s and 1960s, Mark and his colleagues were able to show that “environmental therapy” can stimulate brain growth at a cellular level not only in juveniles but also in adults. For example, he found that rats living in an “enriched environment,” which were given stimulating interactive tasks, performed better at learning activities than those living in passive, impoverished conditions.


A descendent of Lithuanian and Russian Jews who came to America in the 1880s, Mark was born in Rochester, New York, on September 12, 1922. His father was a lawyer and his mother a homemaker who was bilingual in English and German. In an autobiography published in The History of Neuroscience in Autobiography (5: 2006), Rosenzweig described a warm, stimulating upbringing in which his parents fostered a love of languages and cerebral activities, playing word games with their son and daughter to improve their vocabulary.


He attended public schools in Rochester and was selected class valedictorian in both grammar school and high school. In 1940, he entered the University of Rochester, and while he started out drawn to history, his fascination for psychology won out. In 1943, he earned a bachelor’s degree in psychology and in 1944 went on to earn a master’s degree, specializing in the brain mechanism of auditory perception.


In 1944, he was drafted into the Navy, stationed at the Anacostia Naval base in Washington D.C., and put to work as a radar technician. When President Franklin Delano Roosevelt died in 1945, he marched in the funeral procession. Later, he shipped out across the Pacific Ocean to Tsingtao Harbor in China. He was stationed on the seaplane tender USS Chincoteague.


After being discharged from the Navy in 1946, Mark was accepted to Harvard University, where he worked in the Psycho-Acoustic Laboratory. In his 1949 doctoral thesis, he demonstrated that electrodes placed on the skull could pick up “electrical activity of all the auditory stations from the cochlea to the cortex.” This meant that the “activity of subcortical centers can be studied without surgical invasion of the nervous system,” he later pointed out. In the 1970s, his method of testing stations of the auditory system via the surface of the brain was developed to identify newborns with hearing loss.


In 1949, Mark was offered an assistant professorship in physiological psychology at UC Berkeley. At the time, all University employees were required to sign a loyalty oath, which stirred much protest, and made Mark wary about taking the job. But, he wrote in his autobiography, Professor Edward C. Tolman, for whom UC Berkeley’s psychology department building is now named, told him, “If you are interested in the position, take it. There are enough senior professors to maintain the fight against the loyalty oath and we don’t want to cripple the future of the university by stopping recruitment of young people.” Mark accepted this position and was appointed in 1950, although he did not arrive on the Berkeley campus until 1951.


At UC Berkeley, he continued his investigation into “binaural perception,” but soon he and his colleagues were drawn to the study of learning and memory, and thus began their investigations of the whole brain: “Our first reports that differential experience induces measurable changes in the brain were greeted with skepticism and incredulity,” he wrote. But in later years, their findings gained acceptance.


“We did not invent the concept of the ‘enriched environment,’ but I believe that our publications introduced the concept and the term to the neuroscience community,” he wrote. In 1982, he received the American Psychological Association’s Award for Distinguished Scientific Contributions for his research demonstrating that weight, chemistry, and ultrastructure of brain components are affected by environmental stimulation.

A strong supporter of public education and equal opportunity, in 1964 Mark Rosenzweig served with UC Berkeley physics Nobelist Owen Chamberlain as cochair of the Special Opportunity Scholarship Committee, designed to prepare underprivileged high school students for university education. Their initiative developed into the federal program known as Upward Bound.

Another of Mark’s passions was psychology as an international science, and he became heavily involved in the International Union of Psychological Science, which he served as president from 1988 to 1992. In turn, Mark received the American Psychological Association’s Contribution to International Psychology Award in 1998.


Among other accolades, Mark Rosenzweig was awarded the Berkeley Citation in 1992. He also received honorary doctorates from the Université René Descartes in Paris, the Université Louis Pasteur in Strasbourg and the Université de Montréal. He served as editor of the Annual Review of Psychology from 1968 to 1994. Mark was also elected to the National Academy of Sciences.


A memorial gathering, arranged by Mark Rosenzweig’s children, was held at the Men’s Faculty Club on September 11, 2009. It was attended by colleagues and many former graduate students, as well as his three children and several grandchildren. Mark’s son Philip provided a set of stories that completed the portrait of Mark Rosenzweig as a warm and engaged father and grandfather. “Our father’s dedication to science was matched by his devotion to his family,” said his daughter, Suzanne Washburn. “He enriched our lives through education, travel, and laughter.”


For those of us who knew Mark as a colleague, he was also a friend, a fine scholar and a formal, old-fashioned gentleman. But, as was recounted by speaker after speaker at the memorial gathering, he also had a marvelous sense of humor, which emerged with a special impish smile. Many of those reminiscences, along with those of other students and colleagues who knew Mark, can be read in the December 2009 issue of The Observer, published by the Association for Psychological Science.


Mark Rosenzweig is survived by his daughters, Anne Janine Rosenzweig of Morgan Hill, California, and Suzanne Jacqueline Washburn of Moraga, California; son, Philip Mark Rosenzweig of Sedbergh, England; sister, Patty Epstein of Green Valley, Arizona; six grandchildren and two great-grandchildren. He was preceded in death by his wife of 60 years, Janine, who passed away in 2008.



Stephen E. Glickman                                                                                  2010

Ervin R. Hafter

Donald A. Riley