Estes, died quietly at the age of 92. His health had declined steadily in the last three months since his wife of almost 70 years, Kay, died in May. Since then he had spoken repeatedly of wanting to join her. As per his wishes, he was cremated and interred with Kay and their son, Greg, in Illinois.
Our friend, mentor, and colleague, BillWilliam K. Estes’ long and productive career encompassed the science of learning and memory from behaviorism to cognitive science, with seminal contributions to both. Estes (born June 17, 1919) began his graduate studies under the tutelage of B. F. Skinner during the early 1940s.
The United States had not yet entered World War II. The Germans were using a new technology — rockets — to bomb England. As Londoners heard the whine of the rocket engines approaching, they stopped whatever they were doing — eating, walking, or talking — and waited for the explosions. After the rockets dropped elsewhere and people realized they were safe, they resumed their daily activities. Intrigued by these stories from London, Estes and Skinner developed a new conditioning paradigm for rats that was similar, in some respects, to what Londoners were experiencing. This paradigm, called conditioned suppression, was a new technique for studying learned fear (Estes & Skinner, 1941). Estes and Skinner placed hungry rats in a cage that delivered food pellets whenever the rats pressed a lever. The cage also had a metal grid floor wired to deliver a mild shock to the rats’ feet. Normally, the hungry rats pressed the lever to obtain food; but if the experimenters trained the rats to learn that a tone predicted an upcoming shock, the rats would freeze when they heard the tone and wait for the shock. Measuring this freezing behavior allowed Estes to quantify trial-by-trial changes in the learned response. Within a few years, this conditioned emotional response paradigm became one of the most widely used techniques for studying animal conditioning, and it is still in use today.
As soon as he completed his PhD, Estes was called into military service. He was stationed in the Philippines as the commandant of a prisoner-of-war camp, a not-very-demanding job that gave him lots of free time to read the mathematics books sent from home by Kay. When the war ended, Estes returned to the United States and to the study of psychology. Much to Skinner’s dismay, Estes soon began to stray from his mentor’s strict behaviorism. He started to use mathematics to describe mental events that could only be inferred indirectly from behavioral data, an approach quite unacceptable to behaviorists. Years later, in his autobiography, Skinner bemoaned the loss of Estes as a once-promising behaviorist, speculating that Estes’ preoccupation with mathematical models of unobservable mental events was a war-related injury, resulting perhaps from too much time in the hot Pacific sun (Skinner, 1979).
Estes built on Hull’s mathematical modeling approach to develop new methods for interpreting a wide variety of learning behaviors (Estes, 1950). Most learning theorists of that era, including Hull, assumed that learning should be viewed as the development of associations between a stimulus and a response. For example, suppose that a pigeon is trained to peck whenever it sees a yellow light in order to obtain a bit of food. Hull assumed that this training caused the formation of a direct link between the stimulus and the response and that later presentations of the yellow light would evoke the peck-for-food response. Estes, however, suggested that what seemed to be a single stimulus, such as a yellow light, was really a collection of many different possible elements of yellowness and that only a random subset of these elements are noticed (or “sampled,” in Estes’ terminology) in any given training trial. Only the elements sampled on the current trial were associated with the response. On a different trial, a different subset is sampled, and those elements were now associated with the response. Over time, after many random samples, most elements became associated with the correct response. At this point, any presentation of the light activated a random sample of elements, most of which are already linked with the response.
Estes called his idea stimulus sampling theory. A key principle of the theory is that random variation (“sampling”) is essential for learning, just as it is essential for the adaptation of species in Charles Darwin’s theory of evolution through natural selection (Estes, 1950). Estes’ approach gave a much better account than other theories (such as Hull’s) of the randomness seen in both animal and human learning, and his theory helped to explain why even highly trained individuals don’t always make the same response perfectly every time. On any given trial, it’s always possible that (through sheer randomness) a subset of elements will be activated that are not linked to the response. Estes also showed how stimulus sampling theory explains how animals generalize their learning from one stimulus (e.g., a yellow light) to other, physically similar stimuli (e.g., an orange light), as Pavlov had demonstrated in the 1920s.
Estes’ work marked the resurgence of mathematical methods in psychology, reviving the spirit of Hull’s earlier efforts. Estes and his colleagues established a new subdiscipline of psychology called mathematical psychology, which uses mathematical equations to describe the laws of learning and memory. From his early work in animal conditioning, through his founding role in mathematical psychology, to his later contributions to cognitive psychology, W. K. Estes continued to be a vigorous proponent of mathematical models to inform our understanding of learning and memory
W.K. & K.W. Estes Fund
William K. Estes (June 17, 1919 – August 17, 2011) had an enormous influence on psychological science, from his pioneering work in mathematical psychology to his collaborations with colleagues to his mentoring of students, many of whom are now leaders in the fields of learning and memory. He was recognized for his lifetime of contributions with our nation’s highest scientific honor, The National Medal of Science.
Bill also had a special role in APS’s history and success as Founding Editor of our flagship journal Psychological Science. During those years, his wife, Katherine W. (Kay) Estes, served as Founding Managing Editor. Bill and Kay were a team in so many undertakings. The W.K. & K.W. Estes Fund celebrates their contributions to psychological science.
Make a contribution online atwww.psychologicalscience.org/estes-fund
A downloadable form is also available on that webpage.
-Mark Gluck,
Rutgers University
Henry L. “Roddy” Roediger, III
Washington University
I came to Purdue University in July 1973 as a brand new assistant professor. A few months before I arrived, Bill Estes had visited. I was sorry to have missed the chance to meet him, but I heard a good story about the visit from several sources.
The Purdue Psychology Department had been seeking a big equipment grant for new computers from NSF. At the time I arrived, there was a hulking machine there called a Linc 8 (it nearly filled a whole room) and two PDP somethings, maybe PDP-8s. They had cords spewing out the back, and if any one was misplaced, the whole system failed. At any rate, Purdue psychologists wanted more computers. Bill had come for a site visit, and he led the visiting team. I heard all this second hand, since I was not there to witness the event itself.
The faculty figured they needed to show off the computers doing something, so they hooked them up to slide projectors. What Bill and the site visit team saw were these massive computers making slide projectors advance at the rate of one slide every two seconds, something a work-study student could have accomplished with no trouble.
At the final meeting, after making an impassioned plea for why the Purdue Department needed three more computers, the Purdue faculty finished speaking. It was Bill’s turn to talk. A long, incredible, silence ensued as people waited for some kind of response from the leader of the site visit team. Finally, Bill said “Does that mean you would need three more slide projectors, too?”
NSF did not give Purdue the grant. This story about Estes was told and retold for a while in the Department. I might have heard an embellished version, but probably not. I got to know Bill a little bit years later, but never worked up the courage to ask about the Purdue site visit.
University of California, Irvine
Bill and I were among the creators of mathematical psychology during the 1950s. One major accomplishment was the creation of the Mathematical Social Science Board (Robert R. Bush, Clyde H. Coombs, Estes, R. Duncan Luce, and Patrick C. Suppes) that raised NSF funding to run modeling workshops at Stanford University during the summer months in the 1950s and 1960s. A second was the founding in 1964 of theJournal of Mathematical Psychology, which was soon followed by the founding of the Society for Mathematical Psychology. Although our careers frequently overlapped, we never wrote a joint paper. My wife and I often saw Bill and Kay socially when we were both in Cambridge, and we have many warm memories of dinners and concert evenings together as well as the Estes’ annual Holiday Open House. I join others in mourning the loss of a giant in the field.
Rutgers University
The year I entered the University of Minnesota as a freshman, 1939, was a frenetic year of uncertainties and excitement. I was a putative physics major but never became part of that group. Rather, I hung out with friends from high school — Bill Estes, Paul Meehl, and Norm Guttman — in the psychology department, where the “action” and excitement were. It was a time of politics and revolution, Roosevelt, Hitler, Stalin, Franco, Skinner, Hathaway, and Feigl; it was talk, talk, talk and opinion, opinion, opinion. Kay Walker and Keller Breland, who shared graduate student offices on the third ring of the atrium in the psychology building, held forth loudly and obscenely about the virtues of operant psychology while smoking twisted Cajun cigars that Keller had brought from southern Louisiana. (Kay was shedding her “proper lady” upbringing.) Some students were touting Starke Hathaway’s experimental approach to building a personality assessment (the MMPI), others were arguing the merits of various political outlooks, and so on. There were many very bright grad and undergrad students in that group who went on to become famous. Elliott, the psychology chairman and a very proper Harvardian who had hired Skinner at Boring’s suggestion, must have wondered how he got into such a hornet’s nest. As far as I remember, Bill never participated in the violent discussions, but on our walks about campus, it was clear that he had listened.
(Click image to view larger timeline)
Bill was fiercely, but discretely, competitive. I am sure he greatly enjoyed the single B that Paul Meehl got, but we will never know. Bill was comfortable with his talent and accomplishments and tolerant of others.
Meeting Bill on campus was an experience. We’d often cross paths, traveling in opposite directions. I’d greet him, “Hi Bill,” and after walking on for 20 ft. or more, I’d hear, “Hi George.”
Bill and I took college algebra together — a requirement for all liberal arts majors. It was taught by a young instructor, Howard Herbert Campaigne, who went on to be a famous algebraist. He always interrogated students about solutions to problems during class. Whenever he asked Bill a question, Bill would just sit passively, quiet, no response. This always infuriated Campaigne: “Mr. Estes, you must study!” These encounters diminished somewhat as Bill turned in perfect exam after perfect exam, but the grand climax came one day after Campaigne laboriously wrote a particularly long proof on the blackboard. For the first time, Bill raised his hand. Campaigne, with exaggerated sarcasm: “Well, Mr. Estes, you finally have something to say???” Bill: “Three steps.” Campaigne handed Bill the chalk. Bill went to the board, put up a simple, elegant proof on it, and returned to his seat without a word. Campaigne subsequently asked Bill to shift his major to math. Bill reportedly responded, “Too boring.”
The draft was looming. Skinner saved several students (e.g., Guttman, Breland, etc.) by hiring them on the Pigeon Bomb Project (a World War II project in which Skinner attempted to make a pigeon-guided missile). Bill was originally a clinical doctoral student with Hathaway. I don’t know the arrangements, but his famous thesis research on a clinical-type of problem (quantifying anxiety) was conducted with Skinner. After finishing his degree, Bill went into the Army as a clinician. Other students also stayed at Minnesota to finish their degrees and then joined the Army or Navy. More junior students like me had left college to join Uncle Sam’s guided tour and returned after the war to finish up.
After the war, Skinner was recruited by J. R. Kantor as the ideal behaviorist and became chairman of psychology at Indiana University. He assembled a group of faculty that included Bill Estes, Clete Burke, Bill Verplanck, and Norm Guttman with the goal of establishing IU as the center of operant psychology. He had a large pigeon lab, lots of foot soldiers on the G.I. Bill, and lots of funding. He recruited me as a graduate student but ran out of money before I got there and forwarded me to Bill Verplanck, who had a huge Office of Naval Research grant. Luckily for me, Kay Estes was also in Verplanck’s lab. He had hired her on his grant to organize and run statistics on the voluminous amounts of data on the visual detection threshold that he had gathered while in the Navy. Often I overheard her swearing under her breath, “What a _ _ _ _ _ _ _ mess!” Kay took me under her wing, helping wash away the lingering memories of war by lending an understanding ear, editing and re-editing my ungrammatical write-ups for publication, etc. She was a calming influence in those early years of graduate school.
The central preoccupation at IU psychology was learning theory, argued in seminar after seminar, up and down the halls, and over many, many beers. At this time, psychology was on the threshold of becoming a science, and questions were answered by experiments. Many pigeons and some rats labored in these endeavors. Bill, an apostate operant psychologist, labored on his aberrant statistical learning theory much to Skinner’s discomfiture and that of the experimental graduate students, who were now required to complete a math minor. Bill would listen silently as Norm Guttman (a pure by-the-book operant devotee) and I argued loudly and frequently about learning theory, occasionally interjecting to correct our errant ways. It was an exciting time.
Skinner, after many years of denigrating Harvard and the “Eastern Establishment,” turned tail and accepted the offer when it came, leaving behind many unhappy IU faculty and students. When asked why, he said that he “wanted to train the future leaders of the nation in behaviorism.” Instead, he trained a cohort of brilliant graduate students. When Verplanck followed Skinner to Harvard — an opportunity that Estes had rejected — Bill took over as chair of my doctoral committee, for which I am eternally grateful. It cost him and Kay many long hours of editing my thesis. I got my PhD with Bill in January 1951 and was probably one of his early PhDs. When I was elected to the Society of Experimental Psychologists at age 77, Bill sent a congratulatory e-mail: “About time.”
Although Bill eventually left IU to grace many famous institutions during his brilliant career, he told me that he and Kay were never happier than during their years at IU, where they retired. During the 2006 SEP meeting at IU, Bill took me on a tour of the campus to show me how much IU had changed since the early days. He was clearly at home.
Bill was a gentle genius, a renaissance scholar, inspirational and compassionate, and a faithful friend.
Alice F. Healy
University of Colorado, Boulder
I am devastated by the loss of Bill and find it very difficult to write about him. As my mentor, he had a huge impact on my work and my career. Here is an anecdote that I included at the end of my chapter in one of the two 1992 Festschrift volumes honoring Bill that I edited with Stephen Kosslyn and Richard Shiffrin:
A number of years ago, I had a discussion with a group of scientists about the relationship we had with our dissertation advisors. The general consensus seemed to be that the others were initially awed by their advisors but, as time progressed, the gap between their advisor’s knowledge and their own markedly decreased. I explained that my experience was quite different: Although I perceived the same initial gap, for me that gap seemed to grow with time as my appreciation for my advisor’s wisdom steadily increased. Another psychologist in the group responded, “That’s no surprise, Alice; your advisor was Bill Estes.”
An anecdote of a different type concerning Bill:
When I was a young faculty member at Yale, I was invited to serve on an NIMH study section. That seemed like daunting assignment to me at the time. I asked Bill whether he thought I should accept the invitation, and he told me that he had never turned down an invitation for professional service himself. That statement might seem hard to believe. But here is an excerpt from a 2000 encyclopedia entry I wrote about Bill (In A. Kazdin’sEncyclopedia of Psychology), which summarizes Bill’s remarkable service to the field (beyond his role as editor):
“Estes made immense contributions as a leader of many professional organizations in the field. He was one of the founders of the Psychonomic Society and was chair of the governing board in 1972, the year when the society’s journals were started. He was also chair of the organizing group of the Society for Mathematical Psychology and was chair of the society in 1984. Estes helped shape national science policy in his roles as member and chair of numerous committees and commissions of the National Research Council and grant panels of the National Institutes of Health, the National Institute of General Medical Sciences, and the National Science Foundation.”
And that is just the tip of the iceberg.
Healy, A. F. (1992). William K. Estes.American Psychologist,47, 855-857.
Healy, A. F. (2000). Estes, William K. In A. Kazdin (Ed.),Encyclopedia of psychology(Vol. 3, pp. 237-238). Washington, DC: American Psychological Association and Oxford University Press.
University of California, Santa Barbara
I met Bill only once, back in the heyday of split-brain research. Not everyone was excited by these findings. While riding up in the elevator at Rockefeller University, George Miller introduced me to the great American psychologist William Estes and said, “You know Mike, he is the guy that discovered the split-brain phenomenon in humans?” and Estes responded, “Great, now we have two systems we don’t understand!”
It was a sobering moment!