Research Approach

The Modus Operandi of Curt P. Richter

Research Activities of the Psychobiology Laboratory

by Jesse B. Bump

Richter's Approach to Research

Overview of Research Activities

Research Design

Research Subjects

Richter's Approach to Research

Unlike many of his better known contemporaries, such as Walter Cannon, Richter generally preferred the experimental over the theoretical. His research activities fit best into the realm of basic science and are characterized by careful observation and meticulous record keeping. As an experimenter Richter liked to build his own equipment, which he viewed as knowledge conversion tools--allowing him to pose specific questions to animal subjects in a way that they could answer. For example, Richter's Ph.D. thesis on the spontaneous activity of rats employed motion-sensitive cages. He had designed the cages so that movement within them would be registered by a kymograph. Both Richter's questions and his instrumentation became more complex as his career developed, but through all of his experiments he maintained a philosophy of strict observation. This strictness in how Richter observed was balanced by his immense curiosity, which led to great diversity in what he observed. Without regard for traditional disciplinary bounds, Richter pursued results that interested him, following them wherever they might lead.(1)

Overview of Research Activities

Biological Rhythms

Like so many of Richter's investigations, his experiments in biological rhythms were launched by keen chance observations and propelled with ingenious instrumentation. Upon his arrival at Hopkins for graduate study, Richter was given a room containing little other than some caged rats. Through visual inspection he quickly noticed that the rats went through periods of activity and rest. Seeking to standardize his data and increase its volume, he fashioned some motion-detecting cages. Rat motion caused compression and expansion in the hollow rubber cage supports; the accompanying pressure variations were then measured by a kymograph along with the time. At once dramatically increasing the data's volume and standardizing his records, Richter quickly established the basis for a study that had previously existed only beyond the reach of objective methods. Through his new cages, Richter discovered that "spontaneous" activity had a number of predictable patterns. Later, he was able to link the cycles to a variety of determinants, including feeding, stomach contractions, and age of the rat.

Similarly, Richter's many discoveries in biological clocks were linked to clever inventions. The early cage, described above, evolved to include a wheel, which allowed for improved activity quantification. Mounted on their axes, the cages could spin, allowing the rats to run. By counting the number of revolutions, Richter could better determine the level of activity. These "activity cages" yielded data for numerous articles detailing phenomena in rats and supplementing parallel observations on humans. Richter's investigations included topics such as daily activity and sleep cycles, body temperature variation, mood swings, and numerous cycles in psychiatric patients, which led to his famous "shock-phase" hypothesis--that tissues of all organs have cycles which normally balance one another for continuous function, yet can be seen when realigned (in phase) by shock, trauma, allergy, and such.
(See Richter's bibliography on spontaneous activity and biological clocks.)

Behavioral Homeostasis

Perhaps the best known of all the studies Richter conducted, the behavioral homeostasis experiments revealed adaptive appetite in rats under nutritional deprivation. The rats developed "specific hungers" for substances missing in their diets, such as salt, protein, or fat. The key experiment, the "self-selection" or "cafeteria" study, gave the rats 10 or so choices of various nutrients. Richter monitored the animals' intake of the substances as related to deficiencies in their diet. Animals deprived of vitamins in their diets would specifically seek them out when given the choice. Similarly, operations that modified the rats' ability to taste or synthesize various minerals prompted corrective ingestive behaviors. Removing the rat's adrenal glands promoted sodium excretion, but also increased the salt appetite, helping to preserve the total amount available for use by the body.

This holistic maintenance in rats had similar analogues in human beings, which Richter thought would be useful in the study and treatment of psychiatric patients. Partial breakdown of these internal regulatory functions, he reasoned, could be blamed for a host of psychiatric conditions, eating disorders such as anorexia, or catatonic patients' inability to discern external stimuli. Richter's experimental prowess helped to confirm and extend theoretical claims made by Claude Bernard and Walter Cannon about the "wisdom of the body" and its internal homeostasis.
(See Richter's bibliography on homeostasis.)


Richter's contributions in neurology encompassed both the motor and the sympathetic nervous systems. His motor system inquiries were prompted by Sherrington's experiments with decerebrate cats, dogs, and monkeys, which had shown "reflex standing"; the animals would stand rigidly following transection of the brain stem. Noting that all were quadrupeds, Richter wondered whether animals who adapted to other forms of locomotion would behave the same way. Subsequent investigation with the three- and two-toed sloths discovered "reflex hanging," neatly confirming the adaptive nature of decerebrate reflexes. During the experiment Richter observed that the decerebrate sloth also exhibited a grasp reflex, much like that he had seen in newborn humans over in the hospital. This in turn spawned another series of studies of the grasp reflex and its relation to age in animals and humans from cradle to grave.
(See Richter's bibliography on sympathetic nervous system and grasp reflex.)

Richter's studies of the sympathetic nervous system were conducted with both the test of electrical skin resistance, which used the conductivity of nerves as a measure of their continuity, and the galvanic skin response, which was a sensitive index of psychiatric condition. With these methods, he produced pioneering anatomical maps of the sympathetic nervous system, as well as information about its injury and repair, and discovered various patterns of resistance typical of different mental conditions.


Centered on elucidating the differences between domesticated laboratory rats and the wild ones he caught himself on the streets of Baltimore, Richter's domestication studies had important theoretical analogues in the study of human domestication, manifested in problems such as arthritis and sudden death. Domestication of the rat, Richter discovered, had decreased the weight of the adrenal glands, heart, spleen, liver, kidneys, and brain, among other things; increased the weight of some glands; and promoted earlier development of the reproductive system. Furthermore, there were many important behavioral differences. Wild rats proved far feistier, more clever, neophobic, vigilant, unable to breed well, and eager to escape. By contrast, domesticated rats were relatively tame, content with captivity, unlikely to fight with other rats, and able to breed successfully in the lab. Highly suspicious wild rats quickly failed the self-selection tests because they were unwilling to try new substances. In the laboratory setting, this behavior led to starvation, but on the streets, it helped them to avoid poisons. Domesticated rats repeatedly ate poisonous substances along with nutritious ones, as they had apparently lost the suspicion of their feral counterparts.

Many of Richter's observations on wild rats were made in conjunction with an earlier project--developing a rat poison for the government during World War II. Worried that the Axis powers would try to vector disease to U.S. cities with rats, the government contracted the Richter lab to develop a defense. Richter and his collaborators tested and refined many poisons, including the highly successful alpha-naphthyl thiourea (ANTU), which was widely used.
(See Richter's bibliography on domestication and poisons.)

Research Design

Richter's research design was primarily instrument-driven. His nimble mind and adept hands created custom laboratory apparatus for all of his major lines of inquiry. These were the tools that he used to facilitate data gathering and standardization, and as such they represent a cornerstone of his research methodology. Richter's basic goal was to observe and to standardize. Instruments allowed him the chance to observe things that had not before been seen. Theorists had long suspected that there was some kind of behavioral homeostasis mechanism, but it took the inventive creativity of Richter to prove it in the lab through unique cages and meticulous record keeping.

That Richter needed so much specialized equipment speaks more generally to his staunch commitment to free research. He despised result-driven "design research" and was consequently quick to redirect or expand his research efforts to include anything that caught his sharp eye. Galvanic skin response testing led to skin resistance studies, which in turn spawned investigations of nervous anatomy. Spontaneous activity pointed the way to self-selection, biological clocks, rat poison, and domestication. The unpredictable nature of his curiosity frequently steered Richter away from established lines of research and their instruments, forcing him to make his own. In cyclical fashion, his new instruments often revealed capabilities beyond their original intent, which fostered still more lines of research.

Data Analysis

Charts, graphs, drawings, and pictures complement almost all of Richter's nearly 400 papers. The specialized instrumentation that he invented usually included a graphical recording mechanism. Patterns and cycles, which figured large in Richter's understanding of the natural world, are particularly accessible in the various forms of visual representation that he employed. Graphs and charts allowed him to succinctly collect and present the tremendous volume of data that his rat colony generated. At the same time, graphs helped to reduce standard deviation of individual results and facilitated expedient comparisons of the hundreds of individual records generated each week.

Research Subjects



Richter's proximity to the Johns Hopkins Hospital and his friendships with many doctors who worked there facilitated numerous studies that normally would not have been possible. Because of this informal network, patients who were peculiarly afflicted were often directed to Richter. For example, great advances were made in the skin resistance inquiry because Richter had access to a patient with uncommon nerve damage, and another who had no sweat glands. The steady flow of psychiatric patients provided unique opportunites for observation and skin-response testing. Domestication studies of the rat could be related to humans on a limited scale because of similar opportunities.

In addition to patients, Richter used medical and nursing students as subjects, particularly in the grasp reflex experiments. The psychobiology laboratory staff also participated in experiments as human subjects.


1. For experimental philosophy, see Richter, Curt P. Free Research versus Design Research. Science 118, no. 24 July (1953): 91-3; Richter, Curt P. It's a Long Way to Tipperary, the Land of My Genes, In Leaders in the Study of Animal Behavior: Autobiographical Perspectives, edited by D. A. Dewsbury, 356-386. Lewisburg, PA: Bucknell University Press, 1985.

Equipment and instrumentation

The Modus Operandi of Curt P. Richter

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