James A Dinsmoor

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

James “Jim” A. Dinsmoor (October 4, 1921 – August 25, 2005) was an American psychologist who studied how behavior is learned and controlled. He was born in Woburn, Massachusetts, to Daniel and Jean Dinsmoor. He earned a bachelor’s degree from Dartmouth in 1943, then got his Master’s and Ph.D. at Columbia University under William N. Schoenfeld and Fred S. Keller. He was inspired by B.F. Skinner’s work on operant conditioning and spent his career expanding on those ideas. He once called Skinner the “bare bone’s heart” of psychology.

Dinsmoor’s first published study looked at how discriminative and reinforcing stimuli affect behavior. A reinforcing stimulus is something that increases a behavior’s rate, while a discriminative stimulus signals that reinforcement is available. For example, a dinner bell might signal that dinner is ready, and the dinner itself would be the reinforcing outcome. In his experiment, rats pressed a lever for food under different conditions and he found that responses declined more slowly when a discriminative cue was present, even without reinforcement. He concluded that discriminative stimuli act like a kind of secondary reinforcement.

After two years at Columbia as a lecturer, Dinsmoor joined Indiana University in Bloomington in 1951, where he taught for 34 years. He conducted many studies on basic behavioral processes, especially discrimination learning and negative reinforcement. His work helped shape the science of stimulus control—the ways signals influence which behaviors occur.

Dinsmoor built equipment for delivering rewards (like food) and punishers (like electric shock) to laboratory animals, and he urged his students to learn to build the apparatus themselves.

He was active in scholarly communities, serving in leadership roles in the Midwestern Psychological Association (President and Secretary-Treasurer), various positions in the American Psychological Association’s Division 25 (Behavior Analysis), and as President and Chairman of the Board for the Society for the Experimental Analysis of Behavior. He helped organize the Journal of the Experimental Analysis of Behavior, a publication that is still in circulation today.

In the 1960s, Dinsmoor spoke out against the Vietnam War, participating in campus rallies and on the radio. He ran for Congress in 1966 on an anti-war platform but did not win.

Even after retiring in 1986, he continued researching and published about 20 articles, including one the year before his death. He died on August 25, 2005, at age 83 in Laconia, New Hampshire, and was buried in Pine Grove Cemetery in Gilford, New Hampshire. In 2006, he received the Award for Distinguished Service to Behavior Analysis for his many contributions to the field.